draft-ietf-detnet-use-cases-20.txt   rfc8578.txt 
Internet Engineering Task Force E. Grossman, Ed. Internet Engineering Task Force (IETF) E. Grossman, Ed.
Internet-Draft DOLBY Request for Comments: 8578 DOLBY
Intended status: Informational December 19, 2018 Category: Informational May 2019
Expires: June 22, 2019 ISSN: 2070-1721
Deterministic Networking Use Cases Deterministic Networking Use Cases
draft-ietf-detnet-use-cases-20
Abstract Abstract
This draft presents use cases from diverse industries which have in This document presents use cases for diverse industries that have in
common a need for "deterministic flows". "Deterministic" in this common a need for "deterministic flows". "Deterministic" in this
context means that such flows provide guaranteed bandwidth, bounded context means that such flows provide guaranteed bandwidth, bounded
latency, and other properties germane to the transport of time- latency, and other properties germane to the transport of time-
sensitive data. These use cases differ notably in their network sensitive data. These use cases differ notably in their network
topologies and specific desired behavior, providing as a group broad topologies and specific desired behavior, providing as a group broad
industry context for DetNet. For each use case, this document will industry context for Deterministic Networking (DetNet). For each use
identify the use case, identify representative solutions used today, case, this document will identify the use case, identify
and describe potential improvements that DetNet can enable. The Use representative solutions used today, and describe potential
Case Common Themes section then extracts and enumerates the set of improvements that DetNet can enable.
common properties implied by these use cases.
Status of This Memo Status of This Memo
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Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 5 1. Introduction ....................................................6
2. Pro Audio and Video . . . . . . . . . . . . . . . . . . . . . 7 2. Pro Audio and Video .............................................7
2.1. Use Case Description . . . . . . . . . . . . . . . . . . 7 2.1. Use Case Description .......................................7
2.1.1. Uninterrupted Stream Playback . . . . . . . . . . . . 7 2.1.1. Uninterrupted Stream Playback .......................8
2.1.2. Synchronized Stream Playback . . . . . . . . . . . . 8 2.1.2. Synchronized Stream Playback ........................9
2.1.3. Sound Reinforcement . . . . . . . . . . . . . . . . . 8 2.1.3. Sound Reinforcement .................................9
2.1.4. Secure Transmission . . . . . . . . . . . . . . . . . 9 2.1.4. Secure Transmission ................................10
2.1.4.1. Safety . . . . . . . . . . . . . . . . . . . . . 9 2.1.4.1. Safety ....................................10
2.2. Pro Audio Today . . . . . . . . . . . . . . . . . . . . . 9 2.2. Pro Audio Today ...........................................10
2.3. Pro Audio Future . . . . . . . . . . . . . . . . . . . . 9 2.3. Pro Audio in the Future ...................................10
2.3.1. Layer 3 Interconnecting Layer 2 Islands . . . . . . . 9 2.3.1. Layer 3 Interconnecting Layer 2 Islands ............10
2.3.2. High Reliability Stream Paths . . . . . . . . . . . . 10 2.3.2. High-Reliability Stream Paths ......................11
2.3.3. Integration of Reserved Streams into IT Networks . . 10 2.3.3. Integration of Reserved Streams into IT Networks ...11
2.3.4. Use of Unused Reservations by Best-Effort Traffic . . 10 2.3.4. Use of Unused Reservations by Best-Effort Traffic ..11
2.3.5. Traffic Segregation . . . . . . . . . . . . . . . . . 11 2.3.5. Traffic Segregation ................................11
2.3.5.1. Packet Forwarding Rules, VLANs and Subnets . . . 11 2.3.5.1. Packet-Forwarding Rules, VLANs,
2.3.5.2. Multicast Addressing (IPv4 and IPv6) . . . . . . 11 and Subnets ...............................12
2.3.6. Latency Optimization by a Central Controller . . . . 12 2.3.5.2. Multicast Addressing (IPv4 and IPv6) ......12
2.3.7. Reduced Device Cost Due To Reduced Buffer Memory . . 12 2.3.6. Latency Optimization by a Central Controller .......12
2.4. Pro Audio Asks . . . . . . . . . . . . . . . . . . . . . 12 2.3.7. Reduced Device Costs due to Reduced Buffer Memory ..13
3. Electrical Utilities . . . . . . . . . . . . . . . . . . . . 13 2.4. Pro Audio Requests to the IETF ............................13
3.1. Use Case Description . . . . . . . . . . . . . . . . . . 13 3. Electrical Utilities ...........................................14
3.1.1. Transmission Use Cases . . . . . . . . . . . . . . . 13 3.1. Use Case Description ......................................14
3.1.1.1. Protection . . . . . . . . . . . . . . . . . . . 13 3.1.1. Transmission Use Cases .............................14
3.1.1.2. Intra-Substation Process Bus Communications . . . 18 3.1.1.1. Protection ................................14
3.1.1.3. Wide Area Monitoring and Control Systems . . . . 19 3.1.1.2. Intra-substation Process Bus
3.1.1.4. IEC 61850 WAN engineering guidelines requirement Communications ............................21
classification . . . . . . . . . . . . . . . . . 20 3.1.1.3. Wide-Area Monitoring and Control Systems ..23
3.1.2. Generation Use Case . . . . . . . . . . . . . . . . . 21 3.1.1.4. WAN Engineering Guidelines
3.1.2.1. Control of the Generated Power . . . . . . . . . 21 Requirement Classification ................25
3.1.2.2. Control of the Generation Infrastructure . . . . 22
3.1.3. Distribution use case . . . . . . . . . . . . . . . . 27
3.1.3.1. Fault Location Isolation and Service Restoration
(FLISR) . . . . . . . . . . . . . . . . . . . . . 27
3.2. Electrical Utilities Today . . . . . . . . . . . . . . . 28
3.2.1. Security Current Practices and Limitations . . . . . 28
3.3. Electrical Utilities Future . . . . . . . . . . . . . . . 30
3.3.1. Migration to Packet-Switched Network . . . . . . . . 31
3.3.2. Telecommunications Trends . . . . . . . . . . . . . . 31
3.3.2.1. General Telecommunications Requirements . . . . . 31
3.3.2.2. Specific Network topologies of Smart Grid
Applications . . . . . . . . . . . . . . . . . . 32
3.3.2.3. Precision Time Protocol . . . . . . . . . . . . . 33
3.3.3. Security Trends in Utility Networks . . . . . . . . . 34
3.4. Electrical Utilities Asks . . . . . . . . . . . . . . . . 36
4. Building Automation Systems . . . . . . . . . . . . . . . . . 36
4.1. Use Case Description . . . . . . . . . . . . . . . . . . 36
4.2. Building Automation Systems Today . . . . . . . . . . . . 37
4.2.1. BAS Architecture . . . . . . . . . . . . . . . . . . 37
4.2.2. BAS Deployment Model . . . . . . . . . . . . . . . . 38
4.2.3. Use Cases for Field Networks . . . . . . . . . . . . 40
4.2.3.1. Environmental Monitoring . . . . . . . . . . . . 40
4.2.3.2. Fire Detection . . . . . . . . . . . . . . . . . 40
4.2.3.3. Feedback Control . . . . . . . . . . . . . . . . 41
4.2.4. Security Considerations . . . . . . . . . . . . . . . 41
4.3. BAS Future . . . . . . . . . . . . . . . . . . . . . . . 41
4.4. BAS Asks . . . . . . . . . . . . . . . . . . . . . . . . 42
5. Wireless for Industrial Applications . . . . . . . . . . . . 42
5.1. Use Case Description . . . . . . . . . . . . . . . . . . 42
5.1.1. Network Convergence using 6TiSCH . . . . . . . . . . 43
5.1.2. Common Protocol Development for 6TiSCH . . . . . . . 43
5.2. Wireless Industrial Today . . . . . . . . . . . . . . . . 44
5.3. Wireless Industrial Future . . . . . . . . . . . . . . . 44
5.3.1. Unified Wireless Network and Management . . . . . . . 44
5.3.1.1. PCE and 6TiSCH ARQ Retries . . . . . . . . . . . 46
5.3.2. Schedule Management by a PCE . . . . . . . . . . . . 47
5.3.2.1. PCE Commands and 6TiSCH CoAP Requests . . . . . . 47
5.3.2.2. 6TiSCH IP Interface . . . . . . . . . . . . . . . 48
5.3.3. 6TiSCH Security Considerations . . . . . . . . . . . 49
5.4. Wireless Industrial Asks . . . . . . . . . . . . . . . . 49
6. Cellular Radio . . . . . . . . . . . . . . . . . . . . . . . 49
6.1. Use Case Description . . . . . . . . . . . . . . . . . . 49
6.1.1. Network Architecture . . . . . . . . . . . . . . . . 49
6.1.2. Delay Constraints . . . . . . . . . . . . . . . . . . 50
6.1.3. Time Synchronization Constraints . . . . . . . . . . 52
6.1.4. Transport Loss Constraints . . . . . . . . . . . . . 54
6.1.5. Security Considerations . . . . . . . . . . . . . . . 54
6.2. Cellular Radio Networks Today . . . . . . . . . . . . . . 55
6.2.1. Fronthaul . . . . . . . . . . . . . . . . . . . . . . 55
6.2.2. Midhaul and Backhaul . . . . . . . . . . . . . . . . 55
6.3. Cellular Radio Networks Future . . . . . . . . . . . . . 56
6.4. Cellular Radio Networks Asks . . . . . . . . . . . . . . 58
7. Industrial Machine to Machine (M2M) . . . . . . . . . . . . . 59
7.1. Use Case Description . . . . . . . . . . . . . . . . . . 59
7.2. Industrial M2M Communication Today . . . . . . . . . . . 60
7.2.1. Transport Parameters . . . . . . . . . . . . . . . . 60
7.2.2. Stream Creation and Destruction . . . . . . . . . . . 61
7.3. Industrial M2M Future . . . . . . . . . . . . . . . . . . 61 3.1.2. Generation Use Case ................................26
7.4. Industrial M2M Asks . . . . . . . . . . . . . . . . . . . 62 3.1.2.1. Control of the Generated Power ............26
8. Mining Industry . . . . . . . . . . . . . . . . . . . . . . . 62 3.1.2.2. Control of the Generation Infrastructure ..27
8.1. Use Case Description . . . . . . . . . . . . . . . . . . 62 3.1.3. Distribution Use Case ..............................32
8.2. Mining Industry Today . . . . . . . . . . . . . . . . . . 63 3.1.3.1. Fault Location, Isolation, and
8.3. Mining Industry Future . . . . . . . . . . . . . . . . . 63 Service Restoration (FLISR) ...............32
8.4. Mining Industry Asks . . . . . . . . . . . . . . . . . . 64 3.2. Electrical Utilities Today ................................33
9. Private Blockchain . . . . . . . . . . . . . . . . . . . . . 64 3.2.1. Current Security Practices and Their Limitations ...34
9.1. Use Case Description . . . . . . . . . . . . . . . . . . 64 3.3. Electrical Utilities in the Future ........................35
9.1.1. Blockchain Operation . . . . . . . . . . . . . . . . 65 3.3.1. Migration to Packet-Switched Networks ..............36
9.1.2. Blockchain Network Architecture . . . . . . . . . . . 65 3.3.2. Telecommunications Trends ..........................37
9.1.3. Security Considerations . . . . . . . . . . . . . . . 66 3.3.2.1. General Telecommunications Requirements ...37
9.2. Private Blockchain Today . . . . . . . . . . . . . . . . 66 3.3.2.2. Specific Network Topologies of
9.3. Private Blockchain Future . . . . . . . . . . . . . . . . 66 Smart-Grid Applications ...................38
9.4. Private Blockchain Asks . . . . . . . . . . . . . . . . . 67 3.3.2.3. Precision Time Protocol ...................38
10. Network Slicing . . . . . . . . . . . . . . . . . . . . . . . 67 3.3.3. Security Trends in Utility Networks ................39
10.1. Use Case Description . . . . . . . . . . . . . . . . . . 67 3.4. Electrical Utilities Requests to the IETF .................41
10.2. DetNet Applied to Network Slicing . . . . . . . . . . . 67 4. Building Automation Systems (BASs) .............................41
10.2.1. Resource Isolation Across Slices . . . . . . . . . . 67 4.1. Use Case Description ......................................41
10.2.2. Deterministic Services Within Slices . . . . . . . . 68 4.2. BASs Today ................................................42
10.3. A Network Slicing Use Case Example - 5G Bearer Network . 68 4.2.1. BAS Architecture ...................................42
10.4. Non-5G Applications of Network Slicing . . . . . . . . . 69 4.2.2. BAS Deployment Model ...............................44
10.5. Limitations of DetNet in Network Slicing . . . . . . . . 69 4.2.3. Use Cases for Field Networks .......................45
10.6. Network Slicing Today and Future . . . . . . . . . . . . 69 4.2.3.1. Environmental Monitoring ..................45
10.7. Network Slicing Asks . . . . . . . . . . . . . . . . . . 69 4.2.3.2. Fire Detection ............................46
11. Use Case Common Themes . . . . . . . . . . . . . . . . . . . 69 4.2.3.3. Feedback Control ..........................46
11.1. Unified, standards-based network . . . . . . . . . . . . 70 4.2.4. BAS Security Considerations ........................46
11.1.1. Extensions to Ethernet . . . . . . . . . . . . . . . 70 4.3. BASs in the Future ........................................46
11.1.2. Centrally Administered . . . . . . . . . . . . . . . 70 4.4. BAS Requests to the IETF ..................................47
11.1.3. Standardized Data Flow Information Models . . . . . 70 5. Wireless for Industrial Applications ...........................47
11.1.4. L2 and L3 Integration . . . . . . . . . . . . . . . 70 5.1. Use Case Description ......................................47
11.1.5. Consideration for IPv4 . . . . . . . . . . . . . . . 70 5.1.1. Network Convergence Using 6TiSCH ...................48
11.1.6. Guaranteed End-to-End Delivery . . . . . . . . . . . 71 5.1.2. Common Protocol Development for 6TiSCH .............48
11.1.7. Replacement for Multiple Proprietary Deterministic 5.2. Wireless Industrial Today .................................49
Networks . . . . . . . . . . . . . . . . . . . . . . 71 5.3. Wireless Industrial in the Future .........................49
11.1.8. Mix of Deterministic and Best-Effort Traffic . . . . 71 5.3.1. Unified Wireless Networks and Management ...........49
11.1.9. Unused Reserved BW to be Available to Best-Effort 5.3.1.1. PCE and 6TiSCH ARQ Retries ................51
Traffic . . . . . . . . . . . . . . . . . . . . . . 71 5.3.2. Schedule Management by a PCE .......................52
11.1.10. Lower Cost, Multi-Vendor Solutions . . . . . . . . . 71 5.3.2.1. PCE Commands and 6TiSCH CoAP Requests .....52
11.2. Scalable Size . . . . . . . . . . . . . . . . . . . . . 71 5.3.2.2. 6TiSCH IP Interface .......................54
11.2.1. Scalable Number of Flows . . . . . . . . . . . . . . 72 5.3.3. 6TiSCH Security Considerations .....................54
11.3. Scalable Timing Parameters and Accuracy . . . . . . . . 72 5.4. Wireless Industrial Requests to the IETF ..................54
11.3.1. Bounded Latency . . . . . . . . . . . . . . . . . . 72
11.3.2. Low Latency . . . . . . . . . . . . . . . . . . . . 72 6. Cellular Radio .................................................54
11.3.3. Bounded Jitter (Latency Variation) . . . . . . . . . 72 6.1. Use Case Description ......................................54
11.3.4. Symmetrical Path Delays . . . . . . . . . . . . . . 72 6.1.1. Network Architecture ...............................54
11.4. High Reliability and Availability . . . . . . . . . . . 73 6.1.2. Delay Constraints ..................................55
11.5. Security . . . . . . . . . . . . . . . . . . . . . . . . 73 6.1.3. Time-Synchronization Constraints ...................57
11.6. Deterministic Flows . . . . . . . . . . . . . . . . . . 73 6.1.4. Transport-Loss Constraints .........................59
12. Security Considerations . . . . . . . . . . . . . . . . . . . 73 6.1.5. Cellular Radio Network Security Considerations .....60
13. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 74 6.2. Cellular Radio Networks Today .............................60
14. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 75 6.2.1. Fronthaul ..........................................60
14.1. Pro Audio . . . . . . . . . . . . . . . . . . . . . . . 75 6.2.2. Midhaul and Backhaul ...............................60
14.2. Utility Telecom . . . . . . . . . . . . . . . . . . . . 76 6.3. Cellular Radio Networks in the Future .....................61
14.3. Building Automation Systems . . . . . . . . . . . . . . 76 6.4. Cellular Radio Networks Requests to the IETF ..............64
14.4. Wireless for Industrial Applications . . . . . . . . . . 76 7. Industrial Machine to Machine (M2M) ............................64
14.5. Cellular Radio . . . . . . . . . . . . . . . . . . . . . 76 7.1. Use Case Description ......................................64
14.6. Industrial Machine to Machine (M2M) . . . . . . . . . . 77 7.2. Industrial M2M Communications Today .......................66
14.7. Internet Applications and CoMP . . . . . . . . . . . . . 77 7.2.1. Transport Parameters ...............................66
14.8. Network Slicing . . . . . . . . . . . . . . . . . . . . 77 7.2.2. Stream Creation and Destruction ....................67
14.9. Mining . . . . . . . . . . . . . . . . . . . . . . . . . 77 7.3. Industrial M2M in the Future ..............................67
14.10. Private Blockchain . . . . . . . . . . . . . . . . . . . 77 7.4. Industrial M2M Requests to the IETF .......................67
15. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 77 8. Mining Industry ................................................68
16. Informative References . . . . . . . . . . . . . . . . . . . 77 8.1. Use Case Description ......................................68
Appendix A. Use Cases Explicitly Out of Scope for DetNet . . . . 84 8.2. Mining Industry Today .....................................68
A.1. DetNet Scope Limitations . . . . . . . . . . . . . . . . 85 8.3. Mining Industry in the Future .............................69
A.2. Internet-based Applications . . . . . . . . . . . . . . . 85 8.4. Mining Industry Requests to the IETF ......................70
A.2.1. Use Case Description . . . . . . . . . . . . . . . . 86 9. Private Blockchain .............................................70
A.2.1.1. Media Content Delivery . . . . . . . . . . . . . 86 9.1. Use Case Description ......................................70
A.2.1.2. Online Gaming . . . . . . . . . . . . . . . . . . 86 9.1.1. Blockchain Operation ...............................71
A.2.1.3. Virtual Reality . . . . . . . . . . . . . . . . . 86 9.1.2. Blockchain Network Architecture ....................71
A.2.2. Internet-Based Applications Today . . . . . . . . . . 86 9.1.3. Blockchain Security Considerations .................72
A.2.3. Internet-Based Applications Future . . . . . . . . . 86 9.2. Private Blockchain Today ..................................72
A.2.4. Internet-Based Applications Asks . . . . . . . . . . 86 9.3. Private Blockchain in the Future ..........................72
A.3. Pro Audio and Video - Digital Rights Management (DRM) . . 87 9.4. Private Blockchain Requests to the IETF ...................72
A.4. Pro Audio and Video - Link Aggregation . . . . . . . . . 87 10. Network Slicing ...............................................73
A.5. Pro Audio and Video - Deterministic Time to Establish 10.1. Use Case Description .....................................73
Streaming . . . . . . . . . . . . . . . . . . . . . . . . 87 10.2. DetNet Applied to Network Slicing ........................73
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 88 10.2.1. Resource Isolation across Slices ..................73
10.2.2. Deterministic Services within Slices ..............74
10.3. A Network Slicing Use Case Example - 5G Bearer Network ...74
10.4. Non-5G Applications of Network Slicing ...................75
10.5. Limitations of DetNet in Network Slicing .................75
10.6. Network Slicing Today and in the Future ..................75
10.7. Network Slicing Requests to the IETF .....................75
11. Use Case Common Themes ........................................76
11.1. Unified, Standards-Based Networks ........................76
11.1.1. Extensions to Ethernet ............................76
11.1.2. Centrally Administered Networks ...................76
11.1.3. Standardized Data-Flow Information Models .........76
11.1.4. Layer 2 and Layer 3 Integration ...................76
11.1.5. IPv4 Considerations ...............................76
11.1.6. Guaranteed End-to-End Delivery ....................77
11.1.7. Replacement for Multiple Proprietary
Deterministic Networks ............................77
11.1.8. Mix of Deterministic and Best-Effort Traffic ......77
11.1.9. Unused Reserved Bandwidth to Be Available
to Best-Effort Traffic ............................77
11.1.10. Lower-Cost, Multi-Vendor Solutions ...............77
11.2. Scalable Size ............................................78
11.2.1. Scalable Number of Flows ..........................78
11.3. Scalable Timing Parameters and Accuracy ..................78
11.3.1. Bounded Latency ...................................78
11.3.2. Low Latency .......................................78
11.3.3. Bounded Jitter (Latency Variation) ................79
11.3.4. Symmetrical Path Delays ...........................79
11.4. High Reliability and Availability ........................79
11.5. Security .................................................79
11.6. Deterministic Flows ......................................79
12. Security Considerations .......................................80
13. IANA Considerations ...........................................80
14. Informative References ........................................80
Appendix A. Use Cases Explicitly Out of Scope for DetNet ..........90
A.1. DetNet Scope Limitations ...................................90
A.2. Internet-Based Applications ................................90
A.2.1. Use Case Description ...................................91
A.2.1.1. Media Content Delivery .............................91
A.2.1.2. Online Gaming ......................................91
A.2.1.3. Virtual Reality ....................................91
A.2.2. Internet-Based Applications Today ......................91
A.2.3. Internet-Based Applications in the Future ..............91
A.2.4. Internet-Based Applications Requests to the IETF .......92
A.3. Pro Audio and Video - Digital Rights Management (DRM) ......92
A.4. Pro Audio and Video - Link Aggregation .....................92
A.5. Pro Audio and Video - Deterministic Time to Establish
Streaming ..................................................93
Acknowledgments ...................................................93
Contributors ......................................................95
Author's Address ..................................................97
1. Introduction 1. Introduction
This draft documents use cases in diverse industries which require This memo documents use cases for diverse industries that require
deterministic flows over multi-hop paths. DetNet flows can be deterministic flows over multi-hop paths. Deterministic Networking
established from either a Layer 2 or Layer 3 (IP) interface, and such (DetNet) flows can be established from either a Layer 2 or Layer 3
flows can co-exist on an IP network with best-effort traffic. DetNet (IP) interface, and such flows can coexist on an IP network with
also provides for highly reliable flows through provision for best-effort traffic. DetNet also provides for highly reliable flows
redundant paths. through provision for redundant paths.
The DetNet Use Cases explicitly do not suggest any specific design The DetNet use cases explicitly do not suggest any specific design
for DetNet architecture or protocols; these are topics of other for DetNet architecture or protocols; these are topics for other
DetNet drafts. DetNet documents.
The DetNet use cases as originally submitted explicitly were not The DetNet use cases, as originally submitted, explicitly were not
considered by the DetNet Working Group to be concrete requirements; considered by the DetNet Working Group (WG) to be concrete
The DetNet Working Group and Design Team considered these use cases, requirements. The DetNet WG and Design Team considered these use
identifying which elements of them could be feasibly implemented cases, identifying which of their elements could be feasibly
within the charter of DetNet, and as a result certain of the implemented within the charter of DetNet; as a result, certain
originally submitted use cases (or elements of them) have been be originally submitted use cases (or elements thereof) were moved to
moved to the Use Cases Explicitly Out of Scope for DetNet section. Appendix A ("Use Cases Explicitly Out of Scope for DetNet") of this
document.
The DetNet Use Cases document provide context regarding DetNet design This document provides context regarding DetNet design decisions. It
decisions. It also serves a long-lived purpose of helping those also serves a long-lived purpose of helping those learning (or new
learning (or new to) DetNet to understand the types of applications to) DetNet understand the types of applications that can be supported
that can be supported by DetNet. It also allow those WG contributors by DetNet. It also allows those WG contributors who are users to
who are users to ensure that their concerns are addressed by the WG; ensure that their concerns are addressed by the WG; for them, this
for them this document both covers their contribution and provides a document (1) covers their contributions and (2) provides a long-term
long term reference to the problems they expect to be served by the reference regarding the problems that they expect will be served by
technology, both in the short term deliverables and as the technology the technology, in terms of the short-term deliverables and also as
evolves in the future. the technology evolves in the future.
The DetNet Use Cases document has served as a "yardstick" against This document has served as a "yardstick" against which proposed
which proposed DetNet designs can be measured, answering the question DetNet designs can be measured, answering the question "To what
"to what extent does a proposed design satisfy these various use extent does a proposed design satisfy these various use cases?"
cases?"
The Use Case industries covered are professional audio, electrical The industries covered by the use cases in this document are
utilities, building automation systems, wireless for industrial
applications, cellular radio, industrial machine-to-machine, mining, o professional audio and video (Section 2)
private blockchain, and network slicing. For each use case the
following questions are answered: o electrical utilities (Section 3)
o building automation systems (BASs) (Section 4)
o wireless for industrial applications (Section 5)
o cellular radio (Section 6)
o industrial machine to machine (M2M) (Section 7)
o mining (Section 8)
o private blockchain (Section 9)
o network slicing (Section 10)
For each use case, the following questions are answered:
o What is the use case? o What is the use case?
o How is it addressed today? o How is it addressed today?
o How should it be addressed in the future? o How should it be addressed in the future?
o What should the IETF deliver to enable this use case? o What should the IETF deliver to enable this use case?
The level of detail in each use case is intended to be sufficient to The level of detail in each use case is intended to be sufficient to
express the relevant elements of the use case, but not greater than express the relevant elements of the use case but no more than that.
that.
DetNet does not directly address clock distribution or time DetNet does not directly address clock distribution or time
synchronization; these are considered to be part of the overall synchronization; these are considered to be part of the overall
design and implementation of a time-sensitive network, using existing design and implementation of a time-sensitive network, using existing
(or future) time-specific protocols (such as [IEEE8021AS] and/or (or future) time-specific protocols (such as [IEEE-8021AS] and/or
[RFC5905]). [RFC5905]).
Section 11 enumerates the set of common properties implied by these
use cases.
2. Pro Audio and Video 2. Pro Audio and Video
2.1. Use Case Description 2.1. Use Case Description
The professional audio and video industry ("ProAV") includes: The professional audio and video industry ("ProAV") includes:
o Music and film content creation o Music and film content creation
o Broadcast o Broadcast
o Cinema o Cinema
o Live sound o Live sound
o Public address, media and emergency systems at large venues o Public address, media, and emergency systems at large venues
(airports, stadiums, churches, theme parks). (e.g., airports, stadiums, churches, theme parks)
These industries have already transitioned audio and video signals These industries have already transitioned audio and video signals
from analog to digital. However, the digital interconnect systems from analog to digital. However, the digital interconnect systems
remain primarily point-to-point with a single (or small number of) remain primarily point to point, with a single signal or a small
signals per link, interconnected with purpose-built hardware. number of signals per link, interconnected with purpose-built
hardware.
These industries are now transitioning to packet-based infrastructure These industries are now transitioning to packet-based
to reduce cost, increase routing flexibility, and integrate with infrastructures to reduce cost, increase routing flexibility, and
existing IT infrastructure. integrate with existing IT infrastructures.
Today ProAV applications have no way to establish deterministic flows Today, ProAV applications have no way to establish deterministic
from a standards-based Layer 3 (IP) interface, which is a fundamental flows from a standards-based Layer 3 (IP) interface; this is a
limitation to the use cases described here. Today deterministic fundamental limitation of the use cases described here. Today,
flows can be created within standards-based layer 2 LANs (e.g. using deterministic flows can be created within standards-based Layer 2
IEEE 802.1 AVB) however these are not routable via IP and thus are LANs (e.g., using IEEE 802.1 TSN ("TSN" stands for "Time-Sensitive
not effective for distribution over wider areas (for example Networking")); however, these flows are not routable via IP and thus
are not effective for distribution over wider areas (for example,
broadcast events that span wide geographical areas). broadcast events that span wide geographical areas).
It would be highly desirable if such flows could be routed over the It would be highly desirable if such flows could be routed over the
open Internet, however solutions with more limited scope (e.g. open Internet; however, solutions of more-limited scope (e.g.,
enterprise networks) would still provide a substantial improvement. enterprise networks) would still provide substantial improvements.
The following sections describe specific ProAV use cases. The following sections describe specific ProAV use cases.
2.1.1. Uninterrupted Stream Playback 2.1.1. Uninterrupted Stream Playback
Transmitting audio and video streams for live playback is unlike Transmitting audio and video streams for live playback is unlike
common file transfer because uninterrupted stream playback in the common file transfer in that uninterrupted stream playback in the
presence of network errors cannot be achieved by re-trying the presence of network errors cannot be achieved by retrying the
transmission; by the time the missing or corrupt packet has been transmission; by the time the missing or corrupt packet has been
identified it is too late to execute a re-try operation. Buffering identified, it is too late to execute a retry operation. Buffering
can be used to provide enough delay to allow time for one or more can be used to provide enough delay to allow time for one or more
retries, however this is not an effective solution in applications retries; however, this is not an effective solution in applications
where large delays (latencies) are not acceptable (as discussed where large delays (latencies) are not acceptable (as discussed
below). below).
Streams with guaranteed bandwidth can eliminate congestion on the Streams with guaranteed bandwidth can eliminate congestion on the
network as a cause of transmission errors that would lead to playback network as a cause of transmission errors that would lead to playback
interruption. Use of redundant paths can further mitigate interruption. The use of redundant paths can further mitigate
transmission errors to provide greater stream reliability. transmission errors and thereby provide greater stream reliability.
Additional techniques such as forward error correction can also be Additional techniques, such as Forward Error Correction (FEC), can
used to improve stream reliability. also be used to improve stream reliability.
2.1.2. Synchronized Stream Playback 2.1.2. Synchronized Stream Playback
Latency in this context is the time between when a signal is Latency in this context is the time between when a signal is
initially sent over a stream and when it is received. A common initially sent over a stream and when it is received. A common
example in ProAV is time-synchronizing audio and video when they take example in ProAV is time-synchronizing audio and video when they take
separate paths through the playback system. In this case the latency separate paths through the playback system. In this case, the
of both the audio and video streams must be bounded and consistent if latency of both the audio stream and the video stream must be bounded
the sound is to remain matched to the movement in the video. A and consistent if the sound is to remain matched to the movement in
common tolerance for audio/video sync is one NTSC video frame (about the video. A common tolerance for audio/video synchronization is one
33ms) and to maintain the audience perception of correct lip sync the National Television System Committee (NTSC) video frame (about
latency needs to be consistent within some reasonable tolerance, for 33 ms); to maintain the audience's perception of correct lip-sync,
example 10%. the latency needs to be consistent within some reasonable tolerance
-- for example, 10%.
A common architecture for synchronizing multiple streams that have A common architecture for synchronizing multiple streams that have
different paths through the network (and thus potentially different different paths through the network (and thus potentially different
latencies) is to enable measurement of the latency of each path, and latencies) enables measurement of the latency of each path and has
have the data sinks (for example speakers) delay (buffer) all packets the data sinks (for example, speakers) delay (buffer) all packets on
on all but the slowest path. Each packet of each stream is assigned all but the slowest path. Each packet of each stream is assigned a
a presentation time which is based on the longest required delay. presentation time that is based on the longest required delay. This
This implies that all sinks must maintain a common time reference of implies that all sinks must maintain a common time reference of
sufficient accuracy, which can be achieved by any of various sufficient accuracy, which can be achieved by various techniques.
techniques.
This type of architecture is commonly implemented using a central This type of architecture is commonly implemented using a central
controller that determines path delays and arbitrates buffering controller that determines path delays and arbitrates buffering
delays. delays.
2.1.3. Sound Reinforcement 2.1.3. Sound Reinforcement
Consider the latency (delay) from when a person speaks into a Consider the latency (delay) between the time when a person speaks
microphone to when their voice emerges from the speaker. If this into a microphone and when their voice emerges from the speaker. If
delay is longer than about 10-15 milliseconds it is noticeable and this delay is longer than about 10-15 ms, it is noticeable and can
can make a sound reinforcement system unusable (see slide 6 of make a sound-reinforcement system unusable (see slide 6 of
[SRP_LATENCY]). (If you have ever tried to speak in the presence of [SRP_LATENCY]). (If you have ever tried to speak in the presence of
a delayed echo of your voice you may know this experience). a delayed echo of your voice, you might be familiar with this
experience.)
Note that the 15ms latency bound includes all parts of the signal Note that the 15 ms latency bound includes all parts of the signal
path, not just the network, so the network latency must be path -- not just the network -- so the network latency must be
significantly less than 15ms. significantly less than 15 ms.
In some cases local performers must perform in synchrony with a In some cases, local performers must perform in synchrony with a
remote broadcast. In such cases the latencies of the broadcast remote broadcast. In such cases, the latencies of the broadcast
stream and the local performer must be adjusted to match each other, stream and the local performer must be adjusted to match each other,
with a worst case of one video frame (33ms for NTSC video). with a worst case of one video frame (33 ms for NTSC video).
In cases where audio phase is a consideration, for example beam- In cases where audio phase is a consideration -- for example,
forming using multiple speakers, latency can be in the 10 microsecond beam-forming using multiple speakers -- latency can be in the 10 us
range (1 audio sample at 96kHz). range (one audio sample at 96 kHz).
2.1.4. Secure Transmission 2.1.4. Secure Transmission
2.1.4.1. Safety 2.1.4.1. Safety
Professional audio systems can include amplifiers that are capable of Professional audio systems can include amplifiers that are capable of
generating hundreds or thousands of watts of audio power which if generating hundreds or thousands of watts of audio power. If used
used incorrectly can cause hearing damage to those in the vicinity. incorrectly, such amplifiers can cause hearing damage to those in the
Apart from the usual care required by the systems operators to vicinity. Apart from the usual care required by the systems
prevent such incidents, the network traffic that controls these operators to prevent such incidents, the network traffic that
devices must be secured (as with any sensitive application traffic). controls these devices must be secured (as with any sensitive
application traffic).
2.2. Pro Audio Today 2.2. Pro Audio Today
Some proprietary systems have been created which enable deterministic Some proprietary systems have been created that enable deterministic
streams at Layer 3 however they are "engineered networks" which streams at Layer 3; however, they are "engineered networks" that
require careful configuration to operate, often require that the require careful configuration to operate and often require that the
system be over-provisioned, and it is implied that all devices on the system be over-provisioned. Also, it is implied that all devices on
network voluntarily play by the rules of that network. To enable the network voluntarily play by the rules of that network. To enable
these industries to successfully transition to an interoperable these industries to successfully transition to an interoperable
multi-vendor packet-based infrastructure requires effective open multi-vendor packet-based infrastructure requires effective open
standards, and establishing relevant IETF standards is a crucial standards. Establishing relevant IETF standards is a crucial factor.
factor.
2.3. Pro Audio Future 2.3. Pro Audio in the Future
2.3.1. Layer 3 Interconnecting Layer 2 Islands 2.3.1. Layer 3 Interconnecting Layer 2 Islands
It would be valuable to enable IP to connect multiple Layer 2 LANs. It would be valuable to enable IP to connect multiple Layer 2 LANs.
As an example, ESPN constructed a state-of-the-art 194,000 sq ft, As an example, ESPN constructed a state-of-the-art 194,000 sq. ft.,
$125 million broadcast studio called DC2. The DC2 network is capable $125-million broadcast studio called "Digital Center 2" (DC2). The
of handling 46 Tbps of throughput with 60,000 simultaneous signals. DC2 network is capable of handling 46 Tbps of throughput with 60,000
Inside the facility are 1,100 miles of fiber feeding four audio simultaneous signals. Inside the facility are 1,100 miles of fiber
control rooms (see [ESPN_DC2] ). feeding four audio control rooms (see [ESPN_DC2]).
In designing DC2 they replaced as much point-to-point technology as In designing DC2, they replaced as much point-to-point technology as
they could with packet-based technology. They constructed seven they could with packet-based technology. They constructed seven
individual studios using layer 2 LANS (using IEEE 802.1 AVB) that individual studios using Layer 2 LANs (using IEEE 802.1 TSN) that
were entirely effective at routing audio within the LANs. However to were entirely effective at routing audio within the LANs. However,
interconnect these layer 2 LAN islands together they ended up using to interconnect these Layer 2 LAN islands together, they ended up
dedicated paths in a custom SDN (Software Defined Networking) router using dedicated paths in a custom SDN (Software-Defined Networking)
because there is no standards-based routing solution available. router because there is no standards-based routing solution
available.
2.3.2. High Reliability Stream Paths 2.3.2. High-Reliability Stream Paths
On-air and other live media streams are often backed up with On-air and other live media streams are often backed up with
redundant links that seamlessly act to deliver the content when the redundant links that seamlessly act to deliver the content when the
primary link fails for any reason. In point-to-point systems this is primary link fails for any reason. In point-to-point systems, this
provided by an additional point-to-point link; the analogous redundancy is provided by an additional point-to-point link; the
requirement in a packet-based system is to provide an alternate path analogous requirement in a packet-based system is to provide an
through the network such that no individual link can bring down the alternate path through the network such that no individual link can
system. bring down the system.
2.3.3. Integration of Reserved Streams into IT Networks 2.3.3. Integration of Reserved Streams into IT Networks
A commonly cited goal of moving to a packet based media A commonly cited goal of moving to a packet-based media
infrastructure is that costs can be reduced by using off the shelf, infrastructure is that costs can be reduced by using off-the-shelf,
commodity network hardware. In addition, economy of scale can be commodity-network hardware. In addition, economy of scale can be
realized by combining media infrastructure with IT infrastructure. realized by combining media infrastructure with IT infrastructure.
In keeping with these goals, stream reservation technology should be In keeping with these goals, stream-reservation technology should be
compatible with existing protocols, and not compromise use of the compatible with existing protocols and should not compromise the use
network for best-effort (non-time-sensitive) traffic. of the network for best-effort (non-time-sensitive) traffic.
2.3.4. Use of Unused Reservations by Best-Effort Traffic 2.3.4. Use of Unused Reservations by Best-Effort Traffic
In cases where stream bandwidth is reserved but not currently used In cases where stream bandwidth is reserved but not currently used
(or is under-utilized) that bandwidth must be available to best- (or is underutilized), that bandwidth must be available to
effort (i.e. non-time-sensitive) traffic. For example a single best-effort (i.e., non-time-sensitive) traffic. For example, a
stream may be nailed up (reserved) for specific media content that single stream may be "nailed up" (reserved) for specific media
needs to be presented at different times of the day, ensuring timely content that needs to be presented at different times of the day,
delivery of that content, yet in between those times the full ensuring timely delivery of that content, yet in between those times
bandwidth of the network can be utilized for best-effort tasks such the full bandwidth of the network can be utilized for best-effort
as file transfers. tasks such as file transfers.
This also addresses a concern of IT network administrators that are This also addresses a concern of IT network administrators that are
considering adding reserved bandwidth traffic to their networks that considering adding reserved-bandwidth traffic to their networks that
"users will reserve large quantities of bandwidth and then never un- "users will reserve large quantities of bandwidth and then never
reserve it even though they are not using it, and soon the network unreserve it even though they are not using it, and soon the network
will have no bandwidth left". will have no bandwidth left."
2.3.5. Traffic Segregation 2.3.5. Traffic Segregation
Sink devices may be low cost devices with limited processing power. Sink devices may be low-cost devices with limited processing power.
In order to not overwhelm the CPUs in these devices it is important In order to not overwhelm the CPUs in these devices, it is important
to limit the amount of traffic that these devices must process. to limit the amount of traffic that these devices must process.
As an example, consider the use of individual seat speakers in a As an example, consider the use of individual seat speakers in a
cinema. These speakers are typically required to be cost reduced cinema. These speakers are typically required to be cost reduced,
since the quantities in a single theater can reach hundreds of seats. since the quantities in a single theater can reach hundreds of seats.
Discovery protocols alone in a one thousand seat theater can generate Discovery protocols alone in a 1,000-seat theater can generate enough
enough broadcast traffic to overwhelm a low powered CPU. Thus an broadcast traffic to overwhelm a low-powered CPU. Thus, an
installation like this will benefit greatly from some type of traffic installation like this will benefit greatly from some type of traffic
segregation that can define groups of seats to reduce traffic within segregation that can define groups of seats to reduce traffic within
each group. All seats in the theater must still be able to each group. All seats in the theater must still be able to
communicate with a central controller. communicate with a central controller.
There are many techniques that can be used to support this feature There are many techniques that can be used to support this feature,
including (but not limited to) the following examples. including (but not limited to) the following examples.
2.3.5.1. Packet Forwarding Rules, VLANs and Subnets 2.3.5.1. Packet-Forwarding Rules, VLANs, and Subnets
Packet forwarding rules can be used to eliminate some extraneous Packet-forwarding rules can be used to eliminate some extraneous
streaming traffic from reaching potentially low powered sink devices, streaming traffic from reaching potentially low-powered sink devices;
however there may be other types of broadcast traffic that should be however, there may be other types of broadcast traffic that should be
eliminated using other means for example VLANs or IP subnets. eliminated via other means -- for example, VLANs or IP subnets.
2.3.5.2. Multicast Addressing (IPv4 and IPv6) 2.3.5.2. Multicast Addressing (IPv4 and IPv6)
Multicast addressing is commonly used to keep bandwidth utilization Multicast addressing is commonly used to keep bandwidth utilization
of shared links to a minimum. of shared links to a minimum.
Because of the MAC Address forwarding nature of Layer 2 bridges it is Because Layer 2 bridges by design forward Media Access Control (MAC)
important that a multicast MAC address is only associated with one addresses, it is important that a multicast MAC address only be
stream. This will prevent reservations from forwarding packets from associated with one stream. This will prevent reservations from
one stream down a path that has no interested sinks simply because forwarding packets from one stream down a path that has no interested
there is another stream on that same path that shares the same sinks simply because there is another stream on that same path that
multicast MAC address. shares the same multicast MAC address.
Since each multicast MAC Address can represent 32 different IPv4 In other words, since each multicast MAC address can represent 32
multicast addresses there must be a process put in place to make sure different IPv4 multicast addresses, there must be a process in place
this does not occur. Requiring use of IPv6 address can achieve this, to make sure that any given multicast MAC address is only associated
however due to their continued prevalence, solutions that are with exactly one IPv4 multicast address. Requiring the use of IPv6
effective for IPv4 installations are also desirable. addresses could help in this regard, due to the much larger address
range of IPv6; however, due to the continued prevalence of IPv4
installations, solutions that are effective for IPv4 installations
would be practical in many more use cases.
2.3.6. Latency Optimization by a Central Controller 2.3.6. Latency Optimization by a Central Controller
A central network controller might also perform optimizations based A central network controller might also perform optimizations based
on the individual path delays, for example sinks that are closer to on the individual path delays; for example, sinks that are closer to
the source can inform the controller that they can accept greater the source can inform the controller that they can accept greater
latency since they will be buffering packets to match presentation latency, since they will be buffering packets to match presentation
times of farther away sinks. The controller might then move a stream times of sinks that are farther away. The controller might then move
reservation on a short path to a longer path in order to free up a stream reservation on a short path to a longer path in order to
bandwidth for other critical streams on that short path. See slides free up bandwidth for other critical streams on that short path. See
3-5 of [SRP_LATENCY]. slides 3-5 of [SRP_LATENCY].
Additional optimization can be achieved in cases where sinks have Additional optimization can be achieved in cases where sinks have
differing latency requirements, for example in a live outdoor concert differing latency requirements; for example, at a live outdoor
the speaker sinks have stricter latency requirements than the concert, the speaker sinks have stricter latency requirements than
recording hardware sinks. See slide 7 of [SRP_LATENCY]. the recording-hardware sinks. See slide 7 of [SRP_LATENCY].
2.3.7. Reduced Device Cost Due To Reduced Buffer Memory 2.3.7. Reduced Device Costs due to Reduced Buffer Memory
Device cost can be reduced in a system with guaranteed reservations Device costs can be reduced in a system with guaranteed reservations
with a small bounded latency due to the reduced requirements for with a small bounded latency due to the reduced requirements for
buffering (i.e. memory) on sink devices. For example, a theme park buffering (i.e., memory) on sink devices. For example, a theme park
might broadcast a live event across the globe via a layer 3 protocol; might broadcast a live event across the globe via a Layer 3 protocol.
in such cases the size of the buffers required is proportional to the In such cases, the size of the buffers required is defined by the
latency bounds and jitter caused by delivery, which depends on the worst-case latency and jitter values of the worst-case segment of the
worst case segment of the end-to-end network path. For example on end-to-end network path. For example, on today's open Internet, the
todays open internet the latency is typically unacceptable for audio latency is typically unacceptable for audio and video streaming
and video streaming without many seconds of buffering. In such without many seconds of buffering. In such scenarios, a single
scenarios a single gateway device at the local network that receives gateway device at the local network that receives the feed from the
the feed from the remote site would provide the expensive buffering remote site would provide the expensive buffering required to mask
required to mask the latency and jitter issues associated with long the latency and jitter issues associated with long-distance delivery.
distance delivery. Sink devices in the local location would have no Sink devices in the local location would have no additional buffering
additional buffering requirements, and thus no additional costs, requirements, and thus no additional costs, beyond those required for
beyond those required for delivery of local content. The sink device delivery of local content. The sink device would be receiving
would be receiving the identical packets as those sent by the source packets identical to those sent by the source and would be unaware of
and would be unaware that there were any latency or jitter issues any latency or jitter issues along the path.
along the path.
2.4. Pro Audio Asks 2.4. Pro Audio Requests to the IETF
o Layer 3 routing on top of AVB (and/or other high QoS networks) o Layer 3 routing on top of Audio Video Bridging (AVB) (and/or other
high-QoS (Quality of Service) networks)
o Content delivery with bounded, lowest possible latency o Content delivery with bounded, lowest possible latency
o IntServ and DiffServ integration with AVB (where practical) o IntServ and DiffServ integration with AVB (where practical)
o Single network for A/V and IT traffic o Single network for A/V and IT traffic
o Standards-based, interoperable, multi-vendor o Standards-based, interoperable, multi-vendor solutions
o IT department friendly
o Enterprise-wide networks (e.g. size of San Francisco but not the o IT-department-friendly networks
whole Internet (yet...))
o Enterprise-wide networks (e.g., the size of San Francisco but not
the whole Internet (yet...))
3. Electrical Utilities 3. Electrical Utilities
3.1. Use Case Description 3.1. Use Case Description
Many systems that an electrical utility deploys today rely on high Many systems that an electrical utility deploys today rely on high
availability and deterministic behavior of the underlying networks. availability and deterministic behavior of the underlying networks.
Presented here are use cases in Transmission, Generation and Presented here are use cases for transmission, generation, and
Distribution, including key timing and reliability metrics. In distribution, including key timing and reliability metrics. In
addition, security issues and industry trends which affect the addition, security issues and industry trends that affect the
architecture of next generation utility networks are discussed. architecture of next-generation utility networks are discussed.
3.1.1. Transmission Use Cases 3.1.1. Transmission Use Cases
3.1.1.1. Protection 3.1.1.1. Protection
Protection means not only the protection of human operators but also "Protection" means not only the protection of human operators but
the protection of the electrical equipment and the preservation of also the protection of the electrical equipment and the preservation
the stability and frequency of the grid. If a fault occurs in the of the stability and frequency of the grid. If a fault occurs in the
transmission or distribution of electricity then severe damage can transmission or distribution of electricity, then severe damage can
occur to human operators, electrical equipment and the grid itself, occur to human operators, electrical equipment, and the grid itself,
leading to blackouts. leading to blackouts.
Communication links in conjunction with protection relays are used to Communication links, in conjunction with protection relays, are used
selectively isolate faults on high voltage lines, transformers, to selectively isolate faults on high-voltage lines, transformers,
reactors and other important electrical equipment. The role of the reactors, and other important electrical equipment. The role of the
teleprotection system is to selectively disconnect a faulty part by teleprotection system is to selectively disconnect a faulty part by
transferring command signals within the shortest possible time. transferring command signals within the shortest possible time.
3.1.1.1.1. Key Criteria 3.1.1.1.1. Key Criteria
The key criteria for measuring teleprotection performance are command The key criteria for measuring teleprotection performance are command
transmission time, dependability and security. These criteria are transmission time, dependability, and security. These criteria are
defined by the IEC standard 60834 as follows: defined by International Electrotechnical Commission (IEC)
Standard 60834 [IEC-60834] as follows:
o Transmission time (Speed): The time between the moment where state o Transmission time (speed): The time between the moment when a
changes at the transmitter input and the moment of the state change occurs at the transmitter input and the moment of the
corresponding change at the receiver output, including propagation corresponding change at the receiver output, including propagation
delay. Overall operating time for a teleprotection system delay. The overall operating time for a teleprotection system is
includes the time for initiating the command at the transmitting the sum of (1) the time required to initiate the command at the
end, the propagation delay over the network (including equipments) transmitting end, (2) the propagation delay over the network
and the selection and decision time at the receiving end, (including equipment), and (3) the time required to make the
including any additional delay due to a noisy environment. necessary selections and decisions at the receiving end, including
any additional delay due to a noisy environment.
o Dependability: The ability to issue and receive valid commands in o Dependability: The ability to issue and receive valid commands in
the presence of interference and/or noise, by minimizing the the presence of interference and/or noise, by minimizing the
probability of missing command (PMC). Dependability targets are Probability of Missing Commands (PMC). Dependability targets are
typically set for a specific bit error rate (BER) level. typically set for a specific Bit Error Rate (BER) level.
o Security: The ability to prevent false tripping due to a noisy o Security: The ability to prevent false tripping due to a noisy
environment, by minimizing the probability of unwanted commands environment, by minimizing the Probability of Unwanted Commands
(PUC). Security targets are also set for a specific bit error (PUC). Security targets are also set for a specific BER level.
rate (BER) level.
Additional elements of the teleprotection system that impact its Additional elements of the teleprotection system that impact its
performance include: performance include:
o Network bandwidth o Network bandwidth
o Failure recovery capacity (aka resiliency) o Failure recovery capacity (aka resiliency)
3.1.1.1.2. Fault Detection and Clearance Timing 3.1.1.1.2. Fault Detection and Clearance Timing
Most power line equipment can tolerate short circuits or faults for Most power-line equipment can tolerate short circuits or faults for
up to approximately five power cycles before sustaining irreversible up to approximately five power cycles before sustaining irreversible
damage or affecting other segments in the network. This translates damage or affecting other segments in the network. This translates
to total fault clearance time of 100ms. As a safety precaution, to a total fault clearance time of 100 ms. As a safety precaution,
however, actual operation time of protection systems is limited to however, the actual operation time of protection systems is limited
70- 80 percent of this period, including fault recognition time, to 70-80% of this period, including fault recognition time, command
command transmission time and line breaker switching time. transmission time, and line breaker switching time.
Some system components, such as large electromechanical switches, Some system components, such as large electromechanical switches,
require particularly long time to operate and take up the majority of require a particularly long time to operate and take up the majority
the total clearance time, leaving only a 10ms window for the of the total clearance time, leaving only a 10 ms window for the
telecommunications part of the protection scheme, independent of the telecommunications part of the protection scheme, independent of the
distance to travel. Given the sensitivity of the issue, new networks distance of travel. Given the sensitivity of the issue, new
impose requirements that are even more stringent: IEC standard 61850 networks impose requirements that are even more stringent: IEC
limits the transfer time for protection messages to 1/4 - 1/2 cycle Standard 61850-5:2013 [IEC-61850-5:2013] limits the transfer time for
or 4 - 8ms (for 60Hz lines) for the most critical messages. protection messages to 1/4-1/2 cycle or 4-8 ms (for 60 Hz lines) for
messages considered the most critical.
3.1.1.1.3. Symmetric Channel Delay 3.1.1.1.3. Symmetric Channel Delay
Teleprotection channels which are differential must be synchronous, Teleprotection channels that are differential must be synchronous;
which means that any delays on the transmit and receive paths must this means that any delays on the transmit and receive paths must
match each other. Teleprotection systems ideally support zero match each other. Ideally, teleprotection systems support zero
asymmetric delay; typical legacy relays can tolerate delay asymmetric delay; typical legacy relays can tolerate delay
discrepancies of up to 750us. discrepancies of up to 750 us.
Some tools available for lowering delay variation below this Some tools available for lowering delay variation below this
threshold are: threshold are as follows:
o For legacy systems using Time Division Multiplexing (TDM), jitter o For legacy systems using Time-Division Multiplexing (TDM), jitter
buffers at the multiplexers on each end of the line can be used to buffers at the multiplexers on each end of the line can be used to
offset delay variation by queuing sent and received packets. The offset delay variation by queuing sent and received packets. The
length of the queues must balance the need to regulate the rate of length of the queues must balance the need to regulate the rate of
transmission with the need to limit overall delay, as larger transmission with the need to limit overall delay, as larger
buffers result in increased latency. buffers result in increased latency.
o For jitter-prone IP packet networks, traffic management tools can o For jitter-prone IP networks, traffic management tools can ensure
ensure that the teleprotection signals receive the highest that the teleprotection signals receive the highest transmission
transmission priority to minimize jitter. priority to minimize jitter.
o Standard packet-based synchronization technologies, such as o Standard packet-based synchronization technologies, such as the
1588-2008 Precision Time Protocol (PTP) and Synchronous Ethernet IEEE 1588-2008 Precision Time Protocol (PTP) [IEEE-1588] and
(Sync-E), can help keep networks stable by maintaining a highly synchronous Ethernet (syncE) [syncE], can help keep networks
accurate clock source on the various network devices. stable by maintaining a highly accurate clock source on the
various network devices.
3.1.1.1.4. Teleprotection Network Requirements (IEC 61850) 3.1.1.1.4. Teleprotection Network Requirements
The following table captures the main network metrics as based on the Table 1 captures the main network metrics. (These metrics are based
IEC 61850 standard. on IEC Standard 61850-5:2013 [IEC-61850-5:2013].)
+-----------------------------+-------------------------------------+ +---------------------------------+---------------------------------+
| Teleprotection Requirement | Attribute | | Teleprotection Requirement | Attribute |
+-----------------------------+-------------------------------------+ +---------------------------------+---------------------------------+
| One way maximum delay | 4-10 ms | | One-way maximum delay | 4-10 ms |
| Asymetric delay required | Yes | | | |
| Maximum jitter | less than 250 us (750 us for legacy | | Asymmetric delay required | Yes |
| | IED) | | | |
| Topology | Point to point, point to Multi- | | Maximum jitter | Less than 250 us (750 us for |
| | point | | | legacy IEDs) |
| Availability | 99.9999 | | | |
| precise timing required | Yes | | Topology | Point to point, point to |
| Recovery time on node | less than 50ms - hitless | | | multipoint |
| failure | | | | |
| performance management | Yes, Mandatory | | Availability | 99.9999% |
| Redundancy | Yes | | | |
| Packet loss | 0.1% to 1% | | Precise timing required | Yes |
+-----------------------------+-------------------------------------+ | | |
| Recovery time on node failure | Less than 50 ms - hitless |
| | |
| Performance management | Yes; mandatory |
| | |
| Redundancy | Yes |
| | |
| Packet loss | 0.1% to 1% |
+---------------------------------+---------------------------------+
Table 1: Teleprotection network requirements Table 1: Teleprotection Network Requirements
3.1.1.1.5. Inter-Trip Protection scheme 3.1.1.1.5. Inter-trip Protection Scheme
"Inter-tripping" is the signal-controlled tripping of a circuit "Inter-tripping" is the signal-controlled tripping of a circuit
breaker to complete the isolation of a circuit or piece of apparatus breaker to complete the isolation of a circuit or piece of apparatus
in concert with the tripping of other circuit breakers. in concert with the tripping of other circuit breakers.
+--------------------------------+----------------------------------+ +---------------------------------+---------------------------------+
| Inter-Trip protection | Attribute | | Inter-trip Protection | Attribute |
| Requirement | | | Requirement | |
+--------------------------------+----------------------------------+ +---------------------------------+---------------------------------+
| One way maximum delay | 5 ms | | One-way maximum delay | 5 ms |
| Asymetric delay required | No | | | |
| Maximum jitter | Not critical | | Asymmetric delay required | No |
| Topology | Point to point, point to Multi- | | | |
| | point | | Maximum jitter | Not critical |
| Bandwidth | 64 Kbps | | | |
| Availability | 99.9999 | | Topology | Point to point, point to |
| precise timing required | Yes | | | multipoint |
| Recovery time on node failure | less than 50ms - hitless | | | |
| performance management | Yes, Mandatory | | Bandwidth | 64 kbps |
| Redundancy | Yes | | | |
| Packet loss | 0.1% | | Availability | 99.9999% |
+--------------------------------+----------------------------------+ | | |
| Precise timing required | Yes |
| | |
| Recovery time on node failure | Less than 50 ms - hitless |
| | |
| Performance management | Yes; mandatory |
| | |
| Redundancy | Yes |
| | |
| Packet loss | 0.1% |
+---------------------------------+---------------------------------+
Table 2: Inter-Trip protection network requirements Table 2: Inter-trip Protection Network Requirements
3.1.1.1.6. Current Differential Protection Scheme 3.1.1.1.6. Current Differential Protection Scheme
Current differential protection is commonly used for line protection, Current differential protection is commonly used for line protection
and is typical for protecting parallel circuits. At both end of the and is typically used to protect parallel circuits. At both ends of
lines the current is measured by the differential relays, and both the lines, the current is measured by the differential relays; both
relays will trip the circuit breaker if the current going into the relays will trip the circuit breaker if the current going into the
line does not equal the current going out of the line. This type of line does not equal the current going out of the line. This type of
protection scheme assumes some form of communications being present protection scheme assumes that some form of communication is present
between the relays at both end of the line, to allow both relays to between the relays at both ends of the line, to allow both relays to
compare measured current values. Line differential protection compare measured current values. Line differential protection
schemes assume a very low telecommunications delay between both schemes assume that the telecommunications delay between both relays
relays, often as low as 5ms. Moreover, as those systems are often is very low -- often as low as 5 ms. Moreover, as those systems are
not time-synchronized, they also assume symmetric telecommunications often not time-synchronized, they also assume that the delay over
paths with constant delay, which allows comparing current measurement symmetric telecommunications paths is constant; this allows the
values taken at the exact same time. comparison of current measurement values taken at exactly the
same time.
+----------------------------------+--------------------------------+ +---------------------------------+---------------------------------+
| Current Differential protection | Attribute | | Current Differential Protection | Attribute |
| Requirement | | | Requirement | |
+----------------------------------+--------------------------------+ +---------------------------------+---------------------------------+
| One way maximum delay | 5 ms | | One-way maximum delay | 5 ms |
| Asymetric delay Required | Yes | | | |
| Maximum jitter | less than 250 us (750us for | | Asymmetric delay required | Yes |
| | legacy IED) | | | |
| Topology | Point to point, point to | | Maximum jitter | Less than 250 us (750 us for |
| | Multi-point | | | legacy IEDs) |
| Bandwidth | 64 Kbps | | | |
| Availability | 99.9999 | | Topology | Point to point, point to |
| precise timing required | Yes | | | multipoint |
| Recovery time on node failure | less than 50ms - hitless | | | |
| performance management | Yes, Mandatory | | Bandwidth | 64 kbps |
| Redundancy | Yes | | | |
| Packet loss | 0.1% | | Availability | 99.9999% |
+----------------------------------+--------------------------------+ | | |
| Precise timing required | Yes |
| | |
| Recovery time on node failure | Less than 50 ms - hitless |
| | |
| Performance management | Yes; mandatory |
| | |
| Redundancy | Yes |
| | |
| Packet loss | 0.1% |
+---------------------------------+---------------------------------+
Table 3: Current Differential Protection metrics Table 3: Current Differential Protection Metrics
3.1.1.1.7. Distance Protection Scheme 3.1.1.1.7. Distance Protection Scheme
Distance (Impedance Relay) protection scheme is based on voltage and The distance (impedance relay) protection scheme is based on voltage
current measurements. The network metrics are similar (but not and current measurements. The network metrics are similar (but not
identical to) Current Differential protection. identical) to the metrics for current differential protection.
+-------------------------------+-----------------------------------+ +---------------------------------+---------------------------------+
| Distance protection | Attribute | | Distance Protection Requirement | Attribute |
| Requirement | | +---------------------------------+---------------------------------+
+-------------------------------+-----------------------------------+ | One-way maximum delay | 5 ms |
| One way maximum delay | 5 ms | | | |
| Asymetric delay Required | No | | Asymmetric delay required | No |
| Maximum jitter | Not critical | | | |
| Topology | Point to point, point to Multi- | | Maximum jitter | Not critical |
| | point | | | |
| Bandwidth | 64 Kbps | | Topology | Point to point, point to |
| Availability | 99.9999 | | | multipoint |
| precise timing required | Yes | | | |
| Recovery time on node failure | less than 50ms - hitless | | Bandwidth | 64 kbps |
| performance management | Yes, Mandatory | | | |
| Redundancy | Yes | | Availability | 99.9999% |
| Packet loss | 0.1% | | | |
+-------------------------------+-----------------------------------+ | Precise timing required | Yes |
| | |
| Recovery time on node failure | Less than 50 ms - hitless |
| | |
| Performance management | Yes; mandatory |
| | |
| Redundancy | Yes |
| | |
| Packet loss | 0.1% |
+---------------------------------+---------------------------------+
Table 4: Distance Protection requirements Table 4: Distance Protection Requirements
3.1.1.1.8. Inter-Substation Protection Signaling 3.1.1.1.8. Inter-substation Protection Signaling
This use case describes the exchange of Sampled Value and/or GOOSE This use case describes the exchange of sampled values and/or GOOSE
(Generic Object Oriented Substation Events) message between (Generic Object Oriented Substation Events) messages between
Intelligent Electronic Devices (IED) in two substations for Intelligent Electronic Devices (IEDs) in two substations for
protection and tripping coordination. The two IEDs are in a master- protection and tripping coordination. The two IEDs are in
slave mode. master-slave mode.
The Current Transformer or Voltage Transformer (CT/VT) in one The Current Transformer or Voltage Transformer (CT/VT) in one
substation sends the sampled analog voltage or current value to the substation sends the sampled analog voltage or current value to the
Merging Unit (MU) over hard wire. The MU sends the time-synchronized Merging Unit (MU) over hard wire. The MU sends the time-synchronized
61850-9-2 sampled values to the slave IED. The slave IED forwards sampled values (as specified by IEC 61850-9-2:2011
the information to the Master IED in the other substation. The [IEC-61850-9-2:2011]) to the slave IED. The slave IED forwards the
master IED makes the determination (for example based on sampled information to the master IED in the other substation. The master
value differentials) to send a trip command to the originating IED. IED makes the determination (for example, based on sampled value
Once the slave IED/Relay receives the GOOSE trip for breaker differentials) to send a trip command to the originating IED. Once
tripping, it opens the breaker. It then sends a confirmation message the slave IED/relay receives the GOOSE message containing the command
back to the master. All data exchanges between IEDs are either to trip the breaker, it opens the breaker. It then sends a
through Sampled Value and/or GOOSE messages. confirmation message back to the master. All data exchanges between
IEDs are through sampled values and/or GOOSE messages.
+----------------------------------+--------------------------------+ +---------------------------------+---------------------------------+
| Inter-Substation protection | Attribute | | Inter-substation Protection | Attribute |
| Requirement | | | Requirement | |
+----------------------------------+--------------------------------+ +---------------------------------+---------------------------------+
| One way maximum delay | 5 ms | | One-way maximum delay | 5 ms |
| Asymetric delay Required | No | | | |
| Maximum jitter | Not critical | | Asymmetric delay required | No |
| Topology | Point to point, point to | | | |
| | Multi-point | | Maximum jitter | Not critical |
| Bandwidth | 64 Kbps | | | |
| Availability | 99.9999 | | Topology | Point to point, point to |
| precise timing required | Yes | | | multipoint |
| Recovery time on node failure | less than 50ms - hitless | | | |
| performance management | Yes, Mandatory | | Bandwidth | 64 kbps |
| Redundancy | Yes | | | |
| Packet loss | 1% | | Availability | 99.9999% |
+----------------------------------+--------------------------------+ | | |
| Precise timing required | Yes |
| | |
| Recovery time on node failure | Less than 50 ms - hitless |
| | |
| Performance management | Yes; mandatory |
| | |
| Redundancy | Yes |
| | |
| Packet loss | 1% |
+---------------------------------+---------------------------------+
Table 5: Inter-Substation Protection requirements Table 5: Inter-substation Protection Requirements
3.1.1.2. Intra-Substation Process Bus Communications 3.1.1.2. Intra-substation Process Bus Communications
This use case describes the data flow from the CT/VT to the IEDs in This use case describes the data flow from the CT/VT to the IEDs in
the substation via the MU. The CT/VT in the substation send the the substation via the MU. The CT/VT in the substation sends the
analog voltage or current values to the MU over hard wire. The MU analog voltage or current values to the MU over hard wire. The MU
converts the analog values into digital format (typically time- converts the analog values into digital format (typically
synchronized Sampled Values as specified by IEC 61850-9-2) and sends time-synchronized sampled values as specified by IEC 61850-9-2:2011
them to the IEDs in the substation. The GPS Master Clock can send [IEC-61850-9-2:2011]) and sends them to the IEDs in the substation.
1PPS or IRIG-B format to the MU through a serial port or IEEE 1588 The Global Positioning System (GPS) Master Clock can send 1PPS or
protocol via a network. Process bus communication using 61850 IRIG-B format to the MU through a serial port or IEEE 1588 protocol
simplifies connectivity within the substation and removes the via a network. 1PPS (One Pulse Per Second) is an electrical signal
requirement for multiple serial connections and removes the slow that has a width of less than 1 second and a sharply rising or
serial bus architectures that are typically used. This also ensures abruptly falling edge that accurately repeats once per second. 1PPS
increased flexibility and increased speed with the use of multicast signals are output by radio beacons, frequency standards, other types
messaging between multiple devices. of precision oscillators, and some GPS receivers. IRIG (Inter-Range
Instrumentation Group) time codes are standard formats for
transferring timing information. Atomic frequency standards and GPS
receivers designed for precision timing are often equipped with an
IRIG output. Process bus communication using IEC 61850-9-2:2011
[IEC-61850-9-2:2011] simplifies connectivity within the substation,
removes the requirement for multiple serial connections, and removes
the slow serial-bus architectures that are typically used. This also
ensures increased flexibility and increased speed with the use of
multicast messaging between multiple devices.
+----------------------------------+--------------------------------+ +---------------------------------+---------------------------------+
| Intra-Substation protection | Attribute | | Intra-substation Protection | Attribute |
| Requirement | | | Requirement | |
+----------------------------------+--------------------------------+ +---------------------------------+---------------------------------+
| One way maximum delay | 5 ms | | One-way maximum delay | 5 ms |
| Asymetric delay Required | No | | | |
| Maximum jitter | Not critical | | Asymmetric delay required | No |
| Topology | Point to point, point to | | | |
| | Multi-point | | Maximum jitter | Not critical |
| Bandwidth | 64 Kbps | | | |
| Availability | 99.9999 | | Topology | Point to point, point to |
| precise timing required | Yes | | | multipoint |
| Recovery time on Node failure | less than 50ms - hitless | | | |
| performance management | Yes, Mandatory | | Bandwidth | 64 kbps |
| Redundancy | Yes - No | | | |
| Packet loss | 0.1% | | Availability | 99.9999% |
+----------------------------------+--------------------------------+ | | |
| Precise timing required | Yes |
| | |
| Recovery time on node failure | Less than 50 ms - hitless |
| | |
| Performance management | Yes; mandatory |
| | |
| Redundancy | Yes or No |
| | |
| Packet loss | 0.1% |
+---------------------------------+---------------------------------+
Table 6: Intra-Substation Protection requirements Table 6: Intra-substation Protection Requirements
3.1.1.3. Wide Area Monitoring and Control Systems 3.1.1.3. Wide-Area Monitoring and Control Systems
The application of synchrophasor measurement data from Phasor The application of synchrophasor measurement data from Phasor
Measurement Units (PMU) to Wide Area Monitoring and Control Systems Measurement Units (PMUs) to wide-area monitoring and control systems
promises to provide important new capabilities for improving system promises to provide important new capabilities for improving system
stability. Access to PMU data enables more timely situational stability. Access to PMU data enables more-timely situational
awareness over larger portions of the grid than what has been awareness over larger portions of the grid than what has been
possible historically with normal SCADA (Supervisory Control and Data possible historically with normal SCADA (Supervisory Control and Data
Acquisition) data. Handling the volume and real-time nature of Acquisition) data. Handling the volume and the real-time nature of
synchrophasor data presents unique challenges for existing synchrophasor data presents unique challenges for existing
application architectures. Wide Area management System (WAMS) makes application architectures. The Wide-Area Management System (WAMS)
it possible for the condition of the bulk power system to be observed makes it possible for the condition of the bulk power system to be
and understood in real-time so that protective, preventative, or observed and understood in real time so that protective,
corrective action can be taken. Because of the very high sampling preventative, or corrective action can be taken. Because of the very
rate of measurements and the strict requirement for time high sampling rate of measurements and the strict requirement for
synchronization of the samples, WAMS has stringent telecommunications time synchronization of the samples, the WAMS has stringent
requirements in an IP network that are captured in the following telecommunications requirements in an IP network, as captured in
table: Table 7:
+----------------------+--------------------------------------------+ +---------------------------------+---------------------------------+
| WAMS Requirement | Attribute | | WAMS Requirement | Attribute |
+----------------------+--------------------------------------------+ +---------------------------------+---------------------------------+
| One way maximum | 50 ms | | One-way maximum delay | 50 ms |
| delay | | | | |
| Asymetric delay | No | | Asymmetric delay required | No |
| Required | | | | |
| Maximum jitter | Not critical | | Maximum jitter | Not critical |
| Topology | Point to point, point to Multi-point, | | | |
| | Multi-point to Multi-point | | Topology | Point to point, point to |
| Bandwidth | 100 Kbps | | | multipoint, multipoint to |
| Availability | 99.9999 | | | multipoint |
| precise timing | Yes | | | |
| required | | | Bandwidth | 100 kbps |
| Recovery time on | less than 50ms - hitless | | | |
| Node failure | | | Availability | 99.9999% |
| performance | Yes, Mandatory | | | |
| management | | | Precise timing required | Yes |
| Redundancy | Yes | | | |
| Packet loss | 1% | | Recovery time on node failure | Less than 50 ms - hitless |
| Consecutive Packet | At least 1 packet per application cycle | | | |
| Loss | must be received. | | Performance management | Yes; mandatory |
+----------------------+--------------------------------------------+ | | |
| Redundancy | Yes |
| | |
| Packet loss | 1% |
| | |
| Consecutive packet loss | At least one packet per |
| | application cycle must be |
| | received. |
+---------------------------------+---------------------------------+
Table 7: WAMS Special Communication Requirements Table 7: WAMS Special Communication Requirements
3.1.1.4. IEC 61850 WAN engineering guidelines requirement 3.1.1.4. WAN Engineering Guidelines Requirement Classification
classification
The IEC (International Electrotechnical Commission) has published a The IEC has published a technical report (TR) that offers guidelines
Technical Report which offers guidelines on how to define and deploy on how to define and deploy Wide-Area Networks (WANs) for the
Wide Area Networks for the interconnections of electric substations, interconnection of electric substations, generation plants, and SCADA
generation plants and SCADA operation centers. The IEC 61850-90-12 operation centers. IEC TR 61850-90-12:2015 [IEC-61850-90-12:2015]
is providing a classification of WAN communication requirements into provides four classes of WAN communication requirements, as
4 classes. Table 8 summarizes these requirements: summarized in Table 8:
+----------------+------------+------------+------------+-----------+ +----------------+-----------+----------+----------+----------------+
| WAN | Class WA | Class WB | Class WC | Class WD | | WAN | Class WA | Class WB | Class WC | Class WD |
| Requirement | | | | | | Requirement | | | | |
+----------------+------------+------------+------------+-----------+ +----------------+-----------+----------+----------+----------------+
| Application | EHV (Extra | HV (High | MV (Medium | General | | Application | EHV | HV (High | MV | General- |
| field | High | Voltage) | Voltage) | purpose | | field | (Extra- | Voltage) | (Medium | purpose |
| | Voltage) | | | | | | High | | Voltage) | |
| Latency | 5 ms | 10 ms | 100 ms | > 100 ms | | | Voltage) | | | |
| Jitter | 10 us | 100 us | 1 ms | 10 ms | | | | | | |
| Latency | 100 us | 1 ms | 10 ms | 100 ms | | Latency | 5 ms | 10 ms | 100 ms | >100 ms |
| Asymetry | | | | | | | | | | |
| Time Accuracy | 1 us | 10 us | 100 us | 10 to 100 | | Jitter | 10 us | 100 us | 1 ms | 10 ms |
| | | | | ms | | | | | | |
| Bit Error rate | 10-7 to | 10-5 to | 10-3 | | | Latency | 100 us | 1 ms | 10 ms | 100 ms |
| | 10-6 | 10-4 | | | | asymmetry | | | | |
| Unavailability | 10-7 to | 10-5 to | 10-3 | | | | | | | |
| | 10-6 | 10-4 | | | | Time accuracy | 1 us | 10 us | 100 us | 10 to 100 ms |
| Recovery delay | Zero | 50 ms | 5 s | 50 s | | | | | | |
| Cyber security | extremely | High | Medium | Medium | | BER | 10^-7 to | 10^-5 to | 10^-3 | |
| | high | | | | | | 10^-6 | 10^-4 | | |
+----------------+------------+------------+------------+-----------+ | | | | | |
| Unavailability | 10^-7 to | 10^-5 to | 10^-3 | |
| | 10^-6 | 10^-4 | | |
| | | | | |
| Recovery delay | Zero | 50 ms | 5 s | 50 s |
| | | | | |
| Cybersecurity | Extremely | High | Medium | Medium |
| | high | | | |
+----------------+-----------+----------+----------+----------------+
Table 8: 61850-90-12 Communication Requirements; Courtesy of IEC Table 8: Communication Requirements (Courtesy of
IEC TR 61850-90-12:2015)
3.1.2. Generation Use Case 3.1.2. Generation Use Case
Energy generation systems are complex infrastructures that require Energy generation systems are complex infrastructures that require
control of both the generated power and the generation control of both the generated power and the generation
infrastructure. infrastructure.
3.1.2.1. Control of the Generated Power 3.1.2.1. Control of the Generated Power
The electrical power generation frequency must be maintained within a The electrical power generation frequency must be maintained within a
very narrow band. Deviations from the acceptable frequency range are very narrow band. Deviations from the acceptable frequency range are
detected and the required signals are sent to the power plants for detected, and the required signals are sent to the power plants for
frequency regulation. frequency regulation.
Automatic Generation Control (AGC) is a system for adjusting the Automatic Generation Control (AGC) is a system for adjusting the
power output of generators at different power plants, in response to power output of generators at different power plants, in response to
changes in the load. changes in the load.
+---------------------------------------------------+---------------+ +---------------------------------+---------------------------------+
| FCAG (Frequency Control Automatic Generation) | Attribute | | FCAG (Frequency Control | Attribute |
| Requirement | | | Automatic Generation) | |
+---------------------------------------------------+---------------+ | Requirement | |
| One way maximum delay | 500 ms | +---------------------------------+---------------------------------+
| Asymetric delay Required | No | | One-way maximum delay | 500 ms |
| Maximum jitter | Not critical | | | |
| Topology | Point to | | Asymmetric delay required | No |
| | point | | | |
| Bandwidth | 20 Kbps | | Maximum jitter | Not critical |
| Availability | 99.999 | | | |
| precise timing required | Yes | | Topology | Point to point |
| Recovery time on Node failure | N/A | | | |
| performance management | Yes, | | Bandwidth | 20 kbps |
| | Mandatory | | | |
| Redundancy | Yes | | Availability | 99.999% |
| Packet loss | 1% | | | |
+---------------------------------------------------+---------------+ | Precise timing required | Yes |
| | |
| Recovery time on node failure | N/A |
| | |
| Performance management | Yes; mandatory |
| | |
| Redundancy | Yes |
| | |
| Packet loss | 1% |
+---------------------------------+---------------------------------+
Table 9: FCAG Communication Requirements Table 9: FCAG Communication Requirements
3.1.2.2. Control of the Generation Infrastructure 3.1.2.2. Control of the Generation Infrastructure
The control of the generation infrastructure combines requirements The control of the generation infrastructure combines requirements
from industrial automation systems and energy generation systems. from industrial automation systems and energy generation systems.
This section considers the use case of the control of the generation This section describes the use case for control of the generation
infrastructure of a wind turbine. infrastructure of a wind turbine.
Figure 1 presents the subsystems that operate a wind turbine.
| |
| |
| +-----------------+ | +-----------------+
| | +----+ | | | +----+ |
| | |WTRM| WGEN | | | |WTRM| WGEN |
WROT x==|===| | | WROT x==|===| | |
| | +----+ WCNV| | | +----+ WCNV|
| |WNAC | | |WNAC |
| +---+---WYAW---+--+ | +---+---WYAW---+--+
| | | | | |
skipping to change at page 23, line 27 skipping to change at page 27, line 36
| | | | | | | |
Wind Turbine | +--+-+ Wind Turbine | +--+-+
Controller | | Controller | |
WTUR | | | WTUR | | |
WREP | | | WREP | | |
WSLG | | | WSLG | | |
WALG | WTOW | | WALG | WTOW | |
Figure 1: Wind Turbine Control Network Figure 1: Wind Turbine Control Network
Figure 1 presents the subsystems that operate a wind turbine. These The subsystems shown in Figure 1 include the following:
subsystems include
o WROT (Rotor Control) o WROT (rotor control)
o WNAC (Nacelle Control) (nacelle: housing containing the generator) o WNAC (nacelle control) (nacelle: housing containing the generator)
o WTRM (Transmission Control) o WTRM (transmission control)
o WGEN (Generator) o WGEN (generator)
o WYAW (Yaw Controller) (of the tower head) o WYAW (yaw controller) (of the tower head)
o WCNV (In-Turbine Power Converter) o WCNV (in-turbine power converter)
o WMET (External Meteorological Station providing real time o WTRF (wind turbine transformer information)
information to the controllers of the tower) o WMET (external meteorological station providing real-time
information to the tower's controllers)
Traffic characteristics relevant for the network planning and o WTUR (wind turbine general information)
o WREP (wind turbine report information)
o WSLG (wind turbine state log information)
o WALG (wind turbine analog log information)
o WTOW (wind turbine tower information)
Traffic characteristics relevant to the network planning and
dimensioning process in a wind turbine scenario are listed below. dimensioning process in a wind turbine scenario are listed below.
The values in this section are based mainly on the relevant The values in this section are based mainly on the relevant
references [Ahm14] and [Spe09]. Each logical node (Figure 1) is a references [Ahm14] and [Spe09]. Each logical node (Figure 1) is a
part of the metering network and produces analog measurements and part of the metering network and produces analog measurements and
status information which must comply with their respective data rate status information that must comply with their respective data-rate
constraints. constraints.
+-----------+--------+--------+-------------+---------+-------------+ +-----------+--------+----------+-----------+-----------+-----------+
| Subsystem | Sensor | Analog | Data Rate | Status | Data rate | | Subsystem | Sensor | Analog | Data Rate | Status | Data Rate |
| | Count | Sample | (bytes/sec) | Sample | (bytes/sec) | | | Count | Sample | (bytes/s) | Sample | (bytes/s) |
| | | Count | | Count | | | | | Count | | Count | |
+-----------+--------+--------+-------------+---------+-------------+ +-----------+--------+----------+-----------+-----------+-----------+
| WROT | 14 | 9 | 642 | 5 | 10 | | WROT | 14 | 9 | 642 | 5 | 10 |
| WTRM | 18 | 10 | 2828 | 8 | 16 | | | | | | | |
| WGEN | 14 | 12 | 73764 | 2 | 4 | | WTRM | 18 | 10 | 2828 | 8 | 16 |
| WCNV | 14 | 12 | 74060 | 2 | 4 | | | | | | | |
| WTRF | 12 | 5 | 73740 | 2 | 4 | | WGEN | 14 | 12 | 73764 | 2 | 4 |
| WNAC | 12 | 9 | 112 | 3 | 6 | | | | | | | |
| WYAW | 7 | 8 | 220 | 4 | 8 | | WCNV | 14 | 12 | 74060 | 2 | 4 |
| WTOW | 4 | 1 | 8 | 3 | 6 | | | | | | | |
| WMET | 7 | 7 | 228 | - | - | | WTRF | 12 | 5 | 73740 | 2 | 4 |
+-----------+--------+--------+-------------+---------+-------------+ | | | | | | |
| WNAC | 12 | 9 | 112 | 3 | 6 |
| | | | | | |
| WYAW | 7 | 8 | 220 | 4 | 8 |
| | | | | | |
| WTOW | 4 | 1 | 8 | 3 | 6 |
| | | | | | |
| WMET | 7 | 7 | 228 | - | - |
+-----------+--------+----------+-----------+-----------+-----------+
Table 10: Wind Turbine Data Rate Constraints Table 10: Wind Turbine Data-Rate Constraints
Quality of Service (QoS) constraints for different services are QoS constraints for different services are presented in Table 11.
presented in Table 11. These constraints are defined by IEEE 1646 These constraints are defined by IEEE Standard 1646 [IEEE-1646] and
standard [IEEE1646] and IEC 61400 standard [IEC61400]. IEC Standard 61400 Part 25 [IEC-61400-25].
+---------------------+---------+-------------+---------------------+ +---------------------+---------+-------------+---------------------+
| Service | Latency | Reliability | Packet Loss Rate | | Service | Latency | Reliability | Packet Loss Rate |
+---------------------+---------+-------------+---------------------+ +---------------------+---------+-------------+---------------------+
| Analogue measure | 16 ms | 99.99% | < 10-6 | | Analog measurement | 16 ms | 99.99% | <10^-6 |
| Status information | 16 ms | 99.99% | < 10-6 | | | | | |
| Protection traffic | 4 ms | 100.00% | < 10-9 | | Status information | 16 ms | 99.99% | <10^-6 |
| Reporting and | 1 s | 99.99% | < 10-6 | | | | | |
| Protection traffic | 4 ms | 100.00% | <10^-9 |
| | | | |
| Reporting and | 1 s | 99.99% | <10^-6 |
| logging | | | | | logging | | | |
| | | | |
| Video surveillance | 1 s | 99.00% | No specific | | Video surveillance | 1 s | 99.00% | No specific |
| | | | requirement | | | | | requirement |
| | | | |
| Internet connection | 60 min | 99.00% | No specific | | Internet connection | 60 min | 99.00% | No specific |
| | | | requirement | | | | | requirement |
| Control traffic | 16 ms | 100.00% | < 10-9 | | | | | |
| Data polling | 16 ms | 99.99% | < 10-6 | | Control traffic | 16 ms | 100.00% | <10^-9 |
| | | | |
| Data polling | 16 ms | 99.99% | <10^-6 |
+---------------------+---------+-------------+---------------------+ +---------------------+---------+-------------+---------------------+
Table 11: Wind Turbine Reliability and Latency Constraints Table 11: Wind Turbine Reliability and Latency Constraints
3.1.2.2.1. Intra-Domain Network Considerations 3.1.2.2.1. Intra-domain Network Considerations
A wind turbine is composed of a large set of subsystems including A wind turbine is composed of a large set of subsystems, including
sensors and actuators which require time-critical operation. The sensors and actuators that require time-critical operation. The
reliability and latency constraints of these different subsystems is reliability and latency constraints of these different subsystems are
shown in Table 11. These subsystems are connected to an intra-domain shown in Table 11. These subsystems are connected to an intra-domain
network which is used to monitor and control the operation of the network that is used to monitor and control the operation of the
turbine and connect it to the SCADA subsystems. The different turbine and connect it to the SCADA subsystems. The different
components are interconnected using fiber optics, industrial buses, components are interconnected using fiber optics, industrial buses,
industrial Ethernet, EtherCat, or a combination of them. Industrial industrial Ethernet, EtherCAT [EtherCAT], or a combination thereof.
signaling and control protocols such as Modbus, Profibus, Profinet Industrial signaling and control protocols such as Modbus [MODBUS],
and EtherCat are used directly on top of the Layer 2 transport or PROFIBUS [PROFIBUS], PROFINET [PROFINET], and EtherCAT are used
encapsulated over TCP/IP. directly on top of the Layer 2 transport or encapsulated over TCP/IP.
The Data collected from the sensors and condition monitoring systems The data collected from the sensors and condition-monitoring systems
is multiplexed onto fiber cables for transmission to the base of the is multiplexed onto fiber cables for transmission to the base of the
tower, and to remote control centers. The turbine controller tower and to remote control centers. The turbine controller
continuously monitors the condition of the wind turbine and collects continuously monitors the condition of the wind turbine and collects
statistics on its operation. This controller also manages a large statistics on its operation. This controller also manages a large
number of switches, hydraulic pumps, valves, and motors within the number of switches, hydraulic pumps, valves, and motors within the
wind turbine. wind turbine.
There is usually a controller both at the bottom of the tower and in There is usually a controller at the bottom of the tower and also in
the nacelle. The communication between these two controllers usually the nacelle. The communication between these two controllers usually
takes place using fiber optics instead of copper links. Sometimes, a takes place using fiber optics instead of copper links. Sometimes, a
third controller is installed in the hub of the rotor and manages the third controller is installed in the hub of the rotor and manages the
pitch of the blades. That unit usually communicates with the nacelle pitch of the blades. That unit usually communicates with the nacelle
unit using serial communications. unit using serial communications.
3.1.2.2.2. Inter-Domain network considerations 3.1.2.2.2. Inter-domain Network Considerations
A remote control center belonging to a grid operator regulates the A remote control center belonging to a grid operator regulates the
power output, enables remote actuation, and monitors the health of power output, enables remote actuation, and monitors the health of
one or more wind parks in tandem. It connects to the local control one or more wind parks in tandem. It connects to the local control
center in a wind park over the Internet (Figure 2) via firewalls at center in a wind park over the Internet (Figure 2) via firewalls at
both ends. The AS path between the local control center and the Wind both ends. The Autonomous System (AS) path between the local control
Park typically involves several ISPs at different tiers. For center and the wind park typically involves several ISPs at different
example, a remote control center in Denmark can regulate a wind park tiers. For example, a remote control center in Denmark can regulate
in Greece over the normal public AS path between the two locations. a wind park in Greece over the normal public AS path between the two
locations.
The remote control center is part of the SCADA system, setting the
desired power output to the wind park and reading back the result
once the new power output level has been set. Traffic between the
remote control center and the wind park typically consists of
protocols like IEC 60870-5-104 [IEC-60870-5-104], OPC XML-DA
[OPCXML], Modbus [MODBUS], and SNMP [RFC3411]. At the time of this
writing, traffic flows between the wind farm and the remote control
center are best effort. QoS requirements are not strict, so no SLAs
or service provisioning mechanisms (e.g., VPN) are employed. In case
of events like equipment failure, tolerance for alarm delay is on the
order of minutes, due to redundant systems already in place.
+--------------+ +--------------+
| | | |
| | | |
| Wind Park #1 +----+ | Wind Park #1 +----+
| | | XXXXXX | | | XXXXXX
| | | X XXXXXXXX +----------------+ | | | X XXXXXXXX +----------------+
+--------------+ | XXXX X XXXXX | | +--------------+ | XXXX X XXXXX | |
+---+ XXX | Remote Control | +---+ XXX | Remote Control |
XXX Internet +----+ Center | XXX Internet +----+ Center |
skipping to change at page 26, line 25 skipping to change at page 30, line 47
+--------------+ | XXXXXXX XX | | +--------------+ | XXXXXXX XX | |
| | | XX XXXXXXX +----------------+ | | | XX XXXXXXX +----------------+
| | | XXXXX | | | XXXXX
| Wind Park #2 +----+ | Wind Park #2 +----+
| | | |
| | | |
+--------------+ +--------------+
Figure 2: Wind Turbine Control via Internet Figure 2: Wind Turbine Control via Internet
Future use cases will require bounded latency, bounded jitter and The remote control center is part of the SCADA system, setting the
extraordinary low packet loss for inter-domain traffic flows due to desired power output to the wind park and reading back the result
the softwarization and virtualization of core wind farm equipment once the new power output level has been set. Traffic between the
(e.g. switches, firewalls and SCADA server components). These remote control center and the wind park typically consists of
protocols like IEC 60870-5-104 [IEC-60870-5-104], OPC XML-Data Access
(XML-DA) [OPCXML], Modbus [MODBUS], and SNMP [RFC3411]. At the time
of this writing, traffic flows between the remote control center and
the wind park are best effort. QoS requirements are not strict, so
no Service Level Agreements (SLAs) or service-provisioning mechanisms
(e.g., VPNs) are employed. In the case of such events as equipment
failure, tolerance for alarm delay is on the order of minutes, due to
redundant systems already in place.
Future use cases will require bounded latency, bounded jitter, and
extraordinarily low packet loss for inter-domain traffic flows due to
the softwarization and virtualization of core wind-park equipment
(e.g., switches, firewalls, and SCADA server components). These
factors will create opportunities for service providers to install factors will create opportunities for service providers to install
new services and dynamically manage them from remote locations. For new services and dynamically manage them from remote locations. For
example, to enable fail-over of a local SCADA server, a SCADA server example, to enable failover of a local SCADA server, a SCADA server
in another wind farm site (under the administrative control of the in another wind-park site (under the administrative control of the
same operator) could be utilized temporarily (Figure 3). In that same operator) could be utilized temporarily (Figure 3). In that
case local traffic would be forwarded to the remote SCADA server and case, local traffic would be forwarded to the remote SCADA server,
existing intra-domain QoS and timing parameters would have to be met and existing intra-domain QoS and timing parameters would have to be
for inter-domain traffic flows. met for inter-domain traffic flows.
+--------------+ +--------------+
| | | |
| | | |
| Wind Park #1 +----+ | Wind Park #1 +----+
| | | XXXXXX | | | XXXXXX
| | | X XXXXXXXX +----------------+ | | | X XXXXXXXX +----------------+
+--------------+ | XXXX XXXXX | | +--------------+ | XXXX XXXXX | |
+---+ Operator XXX | Remote Control | +---+ Operator- XXX | Remote Control |
XXX Administered +----+ Center | XXX Administered +----+ Center |
+----+X WAN XXX | | +----+X WAN XXX | |
+--------------+ | XXXXXXX XX | | +--------------+ | XXXXXXX XX | |
| | | XX XXXXXXX +----------------+ | | | XX XXXXXXX +----------------+
| | | XXXXX | | | XXXXX
| Wind Park #2 +----+ | Wind Park #2 +----+
| | | |
| | | |
+--------------+ +--------------+
Figure 3: Wind Turbine Control via Operator Administered WAN Figure 3: Wind Turbine Control via Operator-Administered WAN
3.1.3. Distribution use case 3.1.3. Distribution Use Case
3.1.3.1. Fault Location Isolation and Service Restoration (FLISR) 3.1.3.1. Fault Location, Isolation, and Service Restoration (FLISR)
Fault Location, Isolation, and Service Restoration (FLISR) refers to "Fault Location, Isolation, and Service Restoration (FLISR)" refers
the ability to automatically locate the fault, isolate the fault, and to the ability to automatically locate the fault, isolate the fault,
restore service in the distribution network. This will likely be the and restore service in the distribution network. This will likely
first widespread application of distributed intelligence in the grid. be the first widespread application of distributed intelligence in
the grid.
Static power switch status (open/closed) in the network dictates the The static power-switch status (open/closed) in the network dictates
power flow to secondary substations. Reconfiguring the network in the power flow to secondary substations. Reconfiguring the network
the event of a fault is typically done manually on site to energize/ in the event of a fault is typically done manually on site to
de-energize alternate paths. Automating the operation of substation energize/de-energize alternate paths. Automating the operation of
switchgear allows the flow of power to be altered automatically under substation switchgear allows the flow of power to be altered
fault conditions. automatically under fault conditions.
FLISR can be managed centrally from a Distribution Management System FLISR can be managed centrally from a Distribution Management System
(DMS) or executed locally through distributed control via intelligent (DMS) or executed locally through distributed control via intelligent
switches and fault sensors. switches and fault sensors.
+----------------------+--------------------------------------------+ +---------------------------------+---------------------------------+
| FLISR Requirement | Attribute | | FLISR Requirement | Attribute |
+----------------------+--------------------------------------------+ +---------------------------------+---------------------------------+
| One way maximum | 80 ms | | One-way maximum delay | 80 ms |
| delay | | | | |
| Asymetric delay | No | | Asymmetric delay required | No |
| Required | | | | |
| Maximum jitter | 40 ms | | Maximum jitter | 40 ms |
| Topology | Point to point, point to Multi-point, | | | |
| | Multi-point to Multi-point | | Topology | Point to point, point to |
| Bandwidth | 64 Kbps | | | multipoint, multipoint to |
| Availability | 99.9999 | | | multipoint |
| precise timing | Yes | | | |
| required | | | Bandwidth | 64 kbps |
| Recovery time on | Depends on customer impact | | | |
| Node failure | | | Availability | 99.9999% |
| performance | Yes, Mandatory | | | |
| management | | | Precise timing required | Yes |
| Redundancy | Yes | | | |
| Packet loss | 0.1% | | Recovery time on node failure | Depends on customer impact |
+----------------------+--------------------------------------------+ | | |
| Performance management | Yes; mandatory |
| | |
| Redundancy | Yes |
| | |
| Packet loss | 0.1% |
+---------------------------------+---------------------------------+
Table 12: FLISR Communication Requirements Table 12: FLISR Communication Requirements
3.2. Electrical Utilities Today 3.2. Electrical Utilities Today
Many utilities still rely on complex environments formed of multiple Many utilities still rely on complex environments consisting of
application-specific proprietary networks, including TDM networks. multiple application-specific proprietary networks, including TDM
networks.
In this kind of environment there is no mixing of OT and IT In this kind of environment, there is no mixing of Operation
applications on the same network, and information is siloed between Technology (OT) and IT applications on the same network, and
operational areas. information is siloed between operational areas.
Specific calibration of the full chain is required, which is costly. Specific calibration of the full chain is required; this is costly.
This kind of environment prevents utility operations from realizing This kind of environment prevents utility operations from realizing
the operational efficiency benefits, visibility, and functional operational efficiency benefits, visibility, and functional
integration of operational information across grid applications and integration of operational information across grid applications and
data networks. data networks.
In addition, there are many security-related issues as discussed in In addition, there are many security-related issues, as discussed in
the following section. the following section.
3.2.1. Security Current Practices and Limitations 3.2.1. Current Security Practices and Their Limitations
Grid monitoring and control devices are already targets for cyber Grid-monitoring and control devices are already targets for cyber
attacks, and legacy telecommunications protocols have many intrinsic attacks, and legacy telecommunications protocols have many intrinsic
network-related vulnerabilities. For example, DNP3, Modbus, network-related vulnerabilities. For example, the Distributed
PROFIBUS/PROFINET, and other protocols are designed around a common Network Protocol (DNP3) [IEEE-1815], Modbus, PROFIBUS/PROFINET, and
paradigm of request and respond. Each protocol is designed for a other protocols are designed around a common paradigm of "request and
master device such as an HMI (Human Machine Interface) system to send respond". Each protocol is designed for a master device such as an
commands to subordinate slave devices to retrieve data (reading HMI (Human-Machine Interface) system to send commands to subordinate
inputs) or control (writing to outputs). Because many of these slave devices to perform data retrieval (reading inputs) or control
protocols lack authentication, encryption, or other basic security functions (writing to outputs). Because many of these protocols lack
measures, they are prone to network-based attacks, allowing a authentication, encryption, or other basic security measures, they
malicious actor or attacker to utilize the request-and-respond system are prone to network-based attacks, allowing a malicious actor or
as a mechanism for command-and-control like functionality. Specific attacker to utilize the request-and-respond system as a mechanism for
security concerns common to most industrial control, including functionality similar to command and control. Specific security
utility telecommunication protocols include the following: concerns common to most industrial-control protocols (including
utility telecommunications protocols) include the following:
o Network or transport errors (e.g. malformed packets or excessive o Network or transport errors (e.g., malformed packets or excessive
latency) can cause protocol failure. latency) can cause protocol failure.
o Protocol commands may be available that are capable of forcing o Protocol commands may be available that are capable of forcing
slave devices into inoperable states, including powering-off slave devices into inoperable states, including powering devices
devices, forcing them into a listen-only state, disabling off, forcing them into a listen-only state, or disabling alarming.
alarming.
o Protocol commands may be available that are capable of restarting o Protocol commands may be available that are capable of
communications and otherwise interrupting processes. interrupting processes (e.g., restarting communications).
o Protocol commands may be available that are capable of clearing, o Protocol commands may be available that are capable of clearing,
erasing, or resetting diagnostic information such as counters and erasing, or resetting diagnostic information such as counters and
diagnostic registers. diagnostic registers.
o Protocol commands may be available that are capable of requesting o Protocol commands may be available that are capable of requesting
sensitive information about the controllers, their configurations, sensitive information about the controllers, their configurations,
or other need-to-know information. or other need-to-know information.
o Most protocols are application layer protocols transported over o Most protocols are application-layer protocols transported over
TCP; therefore it is easy to transport commands over non-standard TCP; it is therefore easy to transport commands over non-standard
ports or inject commands into authorized traffic flows. ports or inject commands into authorized traffic flows.
o Protocol commands may be available that are capable of o Protocol commands may be available that are capable of
broadcasting messages to many devices at once (i.e. a potential broadcasting messages to many devices at once (i.e., a
DoS). potential DoS).
o Protocol commands may be available to query the device network to o Protocol commands may be available that will query the device
obtain defined points and their values (i.e. a configuration network to obtain defined points and their values (i.e., perform a
scan). configuration scan).
o Protocol commands may be available that will list all available o Protocol commands may be available that will list all available
function codes (i.e. a function scan). function codes (i.e., perform a function scan).
These inherent vulnerabilities, along with increasing connectivity These inherent vulnerabilities, along with increasing connectivity
between IT an OT networks, make network-based attacks very feasible. between IT and OT networks, make network-based attacks very feasible.
By injecting malicious protocol commands, an attacker could take
Simple injection of malicious protocol commands provides control over control over the target process. Altering legitimate protocol
the target process. Altering legitimate protocol traffic can also traffic can also alter information about a process and disrupt the
alter information about a process and disrupt the legitimate controls legitimate controls that are in place over that process. A
that are in place over that process. A man-in-the-middle attack man-in-the-middle attack could result in (1) improper control over a
could provide both control over a process and misrepresentation of process and (2) misrepresentation of data that is sent back to
data back to operator consoles. operator consoles.
3.3. Electrical Utilities Future 3.3. Electrical Utilities in the Future
The business and technology trends that are sweeping the utility The business and technology trends that are sweeping the utility
industry will drastically transform the utility business from the way industry will drastically transform the utility business from the way
it has been for many decades. At the core of many of these changes it has been for many decades. At the core of many of these changes
is a drive to modernize the electrical grid with an integrated is a drive to modernize the electrical grid with an integrated
telecommunications infrastructure. However, interoperability telecommunications infrastructure. However, interoperability
concerns, legacy networks, disparate tools, and stringent security concerns, legacy networks, disparate tools, and stringent security
requirements all add complexity to the grid transformation. Given requirements all add complexity to the grid's transformation. Given
the range and diversity of the requirements that should be addressed the range and diversity of the requirements that should be addressed
by the next generation telecommunications infrastructure, utilities by the next-generation telecommunications infrastructure, utilities
need to adopt a holistic architectural approach to integrate the need to adopt a holistic architectural approach to integrate the
electrical grid with digital telecommunications across the entire electrical grid with digital telecommunications across the entire
power delivery chain. power delivery chain.
The key to modernizing grid telecommunications is to provide a The key to modernizing grid telecommunications is to provide a
common, adaptable, multi-service network infrastructure for the common, adaptable, multi-service network infrastructure for the
entire utility organization. Such a network serves as the platform entire utility organization. Such a network serves as the platform
for current capabilities while enabling future expansion of the for current capabilities while enabling future expansion of the
network to accommodate new applications and services. network to accommodate new applications and services.
To meet this diverse set of requirements, both today and in the To meet this diverse set of requirements both today and in the
future, the next generation utility telecommunnications network will future, the next-generation utility telecommunications network will
be based on open-standards-based IP architecture. An end-to-end IP be based on an open-standards-based IP architecture. An end-to-end
architecture takes advantage of nearly three decades of IP technology IP architecture takes advantage of nearly three decades of IP
development, facilitating interoperability and device management technology development, facilitating interoperability and device
across disparate networks and devices, as it has been already management across disparate networks and devices, as has already been
demonstrated in many mission-critical and highly secure networks. demonstrated in many mission-critical and highly secure networks.
IPv6 is seen as a future telecommunications technology for the Smart IPv6 is seen as a future telecommunications technology for the smart
Grid; the IEC (International Electrotechnical Commission) and grid; the IEC and different national committees have mandated a
different National Committees have mandated a specific adhoc group specific ad hoc group (AHG8) to define the strategy for migration to
(AHG8) to define the migration strategy to IPv6 for all the IEC TC57 IPv6 for all the IEC Technical Committee 57 (TC 57) power automation
power automation standards. The AHG8 has finalised the work on the standards. The AHG8 has finalized its work on the migration
migration strategy and the following Technical Report has been strategy, and IEC TR 62357-200:2015 [IEC-62357-200:2015] has been
issued: IEC TR 62357-200:2015: Guidelines for migration from Internet issued.
Protocol version 4 (IPv4) to Internet Protocol version 6 (IPv6).
Cloud-based SCADA systems will control and monitor the critical and Cloud-based SCADA systems will control and monitor the critical and
non-critical subsystems of generation systems, for example wind non-critical subsystems of generation systems -- for example, wind
farms. parks.
3.3.1. Migration to Packet-Switched Network 3.3.1. Migration to Packet-Switched Networks
Throughout the world, utilities are increasingly planning for a Throughout the world, utilities are increasingly planning for a
future based on smart grid applications requiring advanced future based on smart-grid applications requiring advanced
telecommunications systems. Many of these applications utilize telecommunications systems. Many of these applications utilize
packet connectivity for communicating information and control signals packet connectivity for communicating information and control signals
across the utility's Wide Area Network (WAN), made possible by across the utility's WAN, made possible by technologies such as
technologies such as multiprotocol label switching (MPLS). The data Multiprotocol Label Switching (MPLS). The data that traverses the
that traverses the utility WAN includes: utility WAN includes:
o Grid monitoring, control, and protection data o Grid monitoring, control, and protection data
o Non-control grid data (e.g. asset data for condition-based o Non-control grid data (e.g., asset data for condition monitoring)
monitoring)
o Physical safety and security data (e.g. voice and video) o Data (e.g., voice and video) related to physical safety and
security
o Remote worker access to corporate applications (voice, maps, o Remote worker access to corporate applications (voice, maps,
schematics, etc.) schematics, etc.)
o Field area network backhaul for smart metering, and distribution o Field area network Backhaul for smart metering
grid management
o Distribution-grid management
o Enterprise traffic (email, collaboration tools, business o Enterprise traffic (email, collaboration tools, business
applications) applications)
WANs support this wide variety of traffic to and from substations, WANs support this wide variety of traffic to and from substations,
the transmission and distribution grid, generation sites, between the transmission and distribution grid, and generation sites; between
control centers, and between work locations and data centers. To control centers; and between work locations and data centers. To
maintain this rapidly expanding set of applications, many utilities maintain this rapidly expanding set of applications, many utilities
are taking steps to evolve present time-division multiplexing (TDM) are taking steps to evolve present TDM-based and frame relay
based and frame relay infrastructures to packet systems. Packet- infrastructures to packet systems. Packet-based networks are
based networks are designed to provide greater functionalities and designed to provide greater functionalities and higher levels of
higher levels of service for applications, while continuing to service for applications, while continuing to deliver reliability and
deliver reliability and deterministic (real-time) traffic support. deterministic (real-time) traffic support.
3.3.2. Telecommunications Trends 3.3.2. Telecommunications Trends
These general telecommunications topics are in addition to the use These general telecommunications topics are provided in addition to
cases that have been addressed so far. These include both current the use cases that have been addressed so far. These include both
and future telecommunications related topics that should be factored current and future telecommunications-related topics that should be
into the network architecture and design. factored into the network architecture and design.
3.3.2.1. General Telecommunications Requirements 3.3.2.1. General Telecommunications Requirements
o IP Connectivity everywhere o IP connectivity everywhere
o Monitoring services everywhere and from different remote centers o Monitoring services everywhere, and from different remote centers
o Move services to a virtual data center
o Unify access to applications / information from the corporate o Moving services to a virtual data center
network
o Unify services o Unified access to applications/information from the corporate
network
o Unified Communications Solutions o Unified services
o Mix of fiber and microwave technologies - obsolescence of SONET/ o Unified communications solutions
SDH or TDM
o Standardize grid telecommunications protocol to opened standard to o Mix of fiber and microwave technologies - obsolescence of the
ensure interoperability Synchronous Optical Network / Synchronous Digital Hierarchy
(SONET/SDH) or TDM
o Reliable Telecommunications for Transmission and Distribution o Standardizing grid telecommunications protocols to open standards,
Substations to ensure interoperability
o IEEE 1588 time synchronization Client / Server Capabilities o Reliable telecommunications for transmission and distribution
substations
o Integration of Multicast Design o IEEE 1588 time-synchronization client/server capabilities
o QoS Requirements Mapping o Integration of multicast design
o Enable Future Network Expansion o Mapping of QoS requirements
o Substation Network Resilience o Enabling future network expansion
o Fast Convergence Design o Substation network resilience
o Scalable Headend Design o Fast convergence design
o Define Service Level Agreements (SLA) and Enable SLA Monitoring o Scalable headend design
o Integration of 3G/4G Technologies and future technologies o Defining SLAs and enabling SLA monitoring
o Integration of 3G/4G technologies and future technologies
o Ethernet Connectivity for Station Bus Architecture o Ethernet connectivity for station bus architecture
o Ethernet Connectivity for Process Bus Architecture o Ethernet connectivity for process bus architecture
o Protection, teleprotection and PMU (Phaser Measurement Unit) on IP o Protection, teleprotection, and PMUs on IP
3.3.2.2. Specific Network topologies of Smart Grid Applications 3.3.2.2. Specific Network Topologies of Smart-Grid Applications
Utilities often have very large private telecommunications networks. Utilities often have very large private telecommunications networks
It covers an entire territory / country. The main purpose of the that can cover an entire territory/country. Until now, the main
network, until now, has been to support transmission network purposes of these networks have been to (1) support transmission
monitoring, control, and automation, remote control of generation network monitoring, control, and automation, (2) support remote
sites, and providing FCAPS (Fault, Configuration, Accounting, control of generation sites, and (3) provide FCAPS (Fault,
Performance, Security) services from centralized network operation Configuration, Accounting, Performance, and Security) services from
centers. centralized network operation centers.
Going forward, one network will support operation and maintenance of Going forward, one network will support the operation and maintenance
electrical networks (generation, transmission, and distribution), of electrical networks (generation, transmission, and distribution),
voice and data services for ten of thousands of employees and for voice and data services for tens of thousands of employees and for
exchange with neighboring interconnections, and administrative exchanges with neighboring interconnections, and administrative
services. To meet those requirements, utility may deploy several services. To meet those requirements, a utility may deploy several
physical networks leveraging different technologies across the physical networks leveraging different technologies across the
country: an optical network and a microwave network for instance. country -- for instance, an optical network and a microwave network.
Each protection and automatism system between two points has two Each protection and automation system between two points has two
telecommunications circuits, one on each network. Path diversity telecommunications circuits, one on each network. Path diversity
between two substations is key. Regardless of the event type between two substations is key. Regardless of the event type
(hurricane, ice storm, etc.), one path needs to stay available so the (hurricane, ice storm, etc.), one path needs to stay available so the
system can still operate. system can still operate.
In the optical network, signals are transmitted over more than tens In the optical network, signals are transmitted over more than tens
of thousands of circuits using fiber optic links, microwave and of thousands of circuits using fiber optic links, microwave links,
telephone cables. This network is the nervous system of the and telephone cables. This network is the nervous system of the
utility's power transmission operations. The optical network utility's power transmission operations. The optical network
represents ten of thousands of km of cable deployed along the power represents tens of thousands of kilometers of cable deployed along
lines, with individual runs as long as 280 km. the power lines, with individual runs as long as 280 km.
3.3.2.3. Precision Time Protocol 3.3.2.3. Precision Time Protocol
Some utilities do not use GPS clocks in generation substations. One Some utilities do not use GPS clocks in generation substations. One
of the main reasons is that some of the generation plants are 30 to of the main reasons is that some of the generation plants are 30 to
50 meters deep under ground and the GPS signal can be weak and 50 meters deep underground and the GPS signal can be weak and
unreliable. Instead, atomic clocks are used. Clocks are unreliable. Instead, atomic clocks are used. Clocks are
synchronized amongst each other. Rubidium clocks provide clock and synchronized amongst each other. Rubidium clocks provide clock and
1ms timestamps for IRIG-B. 1 ms timestamps for IRIG-B.
Some companies plan to transition to the Precision Time Protocol Some companies plan to transition to PTP [IEEE-1588], distributing
(PTP, [IEEE1588]), distributing the synchronization signal over the the synchronization signal over the IP/MPLS network. PTP provides a
IP/MPLS network. PTP provides a mechanism for synchronizing the mechanism for synchronizing the clocks of participating nodes to a
clocks of participating nodes to a high degree of accuracy and high degree of accuracy and precision.
precision.
PTP operates based on the following assumptions: PTP operates based on the following assumptions:
It is assumed that the network eliminates cyclic forwarding of PTP o The network eliminates cyclic forwarding of PTP messages within
messages within each communication path (e.g. by using a spanning each communication path (e.g., by using a spanning tree protocol).
tree protocol).
PTP is tolerant of an occasional missed message, duplicated o PTP is tolerant of an occasional missed message, duplicated
message, or message that arrived out of order. However, PTP message, or message that arrived out of order. However, PTP
assumes that such impairments are relatively rare. assumes that such impairments are relatively rare.
PTP was designed assuming a multicast communication model, however o As designed, PTP expects a multicast communication model; however,
PTP also supports a unicast communication model as long as the PTP also supports a unicast communication model as long as the
behavior of the protocol is preserved. behavior of the protocol is preserved.
Like all message-based time transfer protocols, PTP time accuracy o Like all message-based time transfer protocols, PTP time accuracy
is degraded by delay asymmetry in the paths taken by event is degraded by delay asymmetry in the paths taken by event
messages. Asymmetry is not detectable by PTP, however, if such messages. PTP cannot detect asymmetry, but if such delays are
delays are known a priori, PTP can correct for asymmetry. known a priori, time values can be adjusted to correct for
asymmetry.
IEC 61850 defines the use of IEC/IEEE 61850-9-3:2016. The title is: The use of PTP for power automation is defined in
Precision time protocol profile for power utility automation. It is IEC/IEEE 61850-9-3:2016 [IEC-IEEE-61850-9-3:2016]. It is based on
based on Annex B/IEC 62439 which offers the support of redundant Annex B of IEC 62439-3:2016 [IEC-62439-3:2016], which offers the
attachment of clocks to Parallel Redundancy Protocol (PRP) and High- support of redundant attachment of clocks to Parallel Redundancy
availability Seamless Redundancy (HSR) networks. Protocol (PRP) and High-availability Seamless Redundancy (HSR)
networks.
3.3.3. Security Trends in Utility Networks 3.3.3. Security Trends in Utility Networks
Although advanced telecommunications networks can assist in Although advanced telecommunications networks can assist in
transforming the energy industry by playing a critical role in transforming the energy industry by playing a critical role in
maintaining high levels of reliability, performance, and maintaining high levels of reliability, performance, and
manageability, they also introduce the need for an integrated manageability, they also introduce the need for an integrated
security infrastructure. Many of the technologies being deployed to security infrastructure. Many of the technologies being deployed to
support smart grid projects such as smart meters and sensors can support smart-grid projects such as smart meters and sensors can
increase the vulnerability of the grid to attack. Top security increase the vulnerability of the grid to attack. Top security
concerns for utilities migrating to an intelligent smart grid concerns for utilities migrating to an intelligent smart-grid
telecommunications platform center on the following trends: telecommunications platform center on the following trends:
o Integration of distributed energy resources o Integration of distributed energy resources
o Proliferation of digital devices to enable management, automation, o Proliferation of digital devices to enable management, automation,
protection, and control protection, and control
o Regulatory mandates to comply with standards for critical o Regulatory mandates to comply with standards for critical
infrastructure protection infrastructure protection
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automation, condition-based maintenance, load forecasting, and automation, condition-based maintenance, load forecasting, and
smart metering smart metering
o Demand for new levels of customer service and energy management o Demand for new levels of customer service and energy management
This development of a diverse set of networks to support the This development of a diverse set of networks to support the
integration of microgrids, open-access energy competition, and the integration of microgrids, open-access energy competition, and the
use of network-controlled devices is driving the need for a converged use of network-controlled devices is driving the need for a converged
security infrastructure for all participants in the smart grid, security infrastructure for all participants in the smart grid,
including utilities, energy service providers, large commercial and including utilities, energy service providers, large commercial and
industrial, as well as residential customers. Securing the assets of industrial customers, and residential customers. Securing the assets
electric power delivery systems (from the control center to the of electric power delivery systems (from the control center to the
substation, to the feeders and down to customer meters) requires an substation, to the feeders and down to customer meters) requires an
end-to-end security infrastructure that protects the myriad of end-to-end security infrastructure that protects the myriad of
telecommunications assets used to operate, monitor, and control power telecommunications assets used to operate, monitor, and control power
flow and measurement. flow and measurement.
"Cyber security" refers to all the security issues in automation and "Cybersecurity" refers to all the security issues in automation and
telecommunications that affect any functions related to the operation telecommunications that affect any functions related to the operation
of the electric power systems. Specifically, it involves the of the electric power systems. Specifically, it involves the
concepts of: concepts of:
o Integrity : data cannot be altered undetectably o Integrity: data cannot be altered undetectably
o Authenticity (data origin authentication): the telecommunications o Authenticity (data origin authentication): the telecommunications
parties involved must be validated as genuine parties involved must be validated as genuine
o Authorization : only requests and commands from the authorized o Authorization: only requests and commands from authorized users
users can be accepted by the system can be accepted by the system
o Confidentiality : data must not be accessible to any o Confidentiality: data must not be accessible to any
unauthenticated users unauthenticated users
When designing and deploying new smart grid devices and When designing and deploying new smart-grid devices and
telecommunications systems, it is imperative to understand the telecommunications systems, it is imperative to understand the
various impacts of these new components under a variety of attack various impacts of these new components under a variety of attack
situations on the power grid. Consequences of a cyber attack on the situations on the power grid. The consequences of a cyber attack on
grid telecommunications network can be catastrophic. This is why the grid telecommunications network can be catastrophic. This is why
security for smart grid is not just an ad hoc feature or product, security for the smart grid is not just an ad hoc feature or product;
it's a complete framework integrating both physical and Cyber it's a complete framework integrating both physical and cybersecurity
security requirements and covering the entire smart grid networks requirements and covering the entire smart-grid networks from
from generation to distribution. Security has therefore become one generation to distribution. Security has therefore become one of the
of the main foundations of the utility telecom network architecture main foundations of the utility telecom network architecture and must
and must be considered at every layer with a defense-in-depth be considered at every layer with a defense-in-depth approach.
approach. Migrating to IP based protocols is key to address these
challenges for two reasons: Migrating to IP-based protocols is key to addressing these challenges
for two reasons:
o IP enables a rich set of features and capabilities to enhance the o IP enables a rich set of features and capabilities to enhance the
security posture security posture.
o IP is based on open standards, which allows interoperability o IP is based on open standards; this allows interoperability
between different vendors and products, driving down the costs between different vendors and products, driving down the costs
associated with implementing security solutions in OT networks. associated with implementing security solutions in OT networks.
Securing OT (Operation technology) telecommunications over packet- Securing OT telecommunications over packet-switched IP networks
switched IP networks follow the same principles that are foundational follows the same principles that are foundational for securing the IT
for securing the IT infrastructure, i.e., consideration must be given infrastructure, i.e., consideration must be given to (1) enforcing
to enforcing electronic access control for both person-to-machine and electronic access control for both person-to-machine and machine-to-
machine-to-machine communications, and providing the appropriate machine communications and (2) providing the appropriate levels of
levels of data privacy, device and platform integrity, and threat data privacy, device and platform integrity, and threat detection and
detection and mitigation. mitigation.
3.4. Electrical Utilities Asks 3.4. Electrical Utilities Requests to the IETF
o Mixed L2 and L3 topologies o Mixed Layer 2 and Layer 3 topologies
o Deterministic behavior o Deterministic behavior
o Bounded latency and jitter o Bounded latency and jitter
o Tight feedback intervals o Tight feedback intervals
o High availability, low recovery time o High availability, low recovery time
o Redundancy, low packet loss o Redundancy, low packet loss
o Precise timing o Precise timing
o Centralized computing of deterministic paths o Centralized computing of deterministic paths
o Distributed configuration may also be useful o Distributed configuration (may also be useful)
4. Building Automation Systems 4. Building Automation Systems (BASs)
4.1. Use Case Description 4.1. Use Case Description
A Building Automation System (BAS) manages equipment and sensors in a A BAS manages equipment and sensors in a building for improving
building for improving residents' comfort, reducing energy residents' comfort, reducing energy consumption, and responding to
consumption, and responding to failures and emergencies. For failures and emergencies. For example, the BAS measures the
example, the BAS measures the temperature of a room using sensors and temperature of a room using sensors and then controls the HVAC
then controls the HVAC (heating, ventilating, and air conditioning) (heating, ventilating, and air conditioning) to maintain a set
to maintain a set temperature and minimize energy consumption. temperature and minimize energy consumption.
A BAS primarily performs the following functions: A BAS primarily performs the following functions:
o Periodically measures states of devices, for example humidity and o Periodically measures states of devices -- for example, humidity
illuminance of rooms, open/close state of doors, FAN speed, etc. and illuminance of rooms, open/close state of doors, fan speed.
o Stores the measured data. o Stores the measured data.
o Provides the measured data to BAS systems and operators. o Provides the measured data to BAS operators.
o Generates alarms for abnormal state of devices. o Generates alarms for abnormal state of devices.
o Controls devices (e.g. turn off room lights at 10:00 PM). o Controls devices (e.g., turns room lights off at 10:00 PM).
4.2. Building Automation Systems Today 4.2. BASs Today
4.2.1. BAS Architecture 4.2.1. BAS Architecture
A typical BAS architecture of today is shown in Figure 4. A typical present-day BAS architecture is shown in Figure 4.
+----------------------------+ +----------------------------+
| | | |
| BMS HMI | | BMS HMI |
| | | | | | | |
| +----------------------+ | | +----------------------+ |
| | Management Network | | | | Management Network | |
| +----------------------+ | | +----------------------+ |
| | | | | | | |
| LC LC | | LC LC |
| | | | | | | |
| +----------------------+ | | +----------------------+ |
| | Field Network | | | | Field Network | |
| +----------------------+ | | +----------------------+ |
| | | | | | | | | | | |
| Dev Dev Dev Dev | | Dev Dev Dev Dev |
| | | |
+----------------------------+ +----------------------------+
BMS := Building Management Server BMS: Building Management Server
HMI := Human Machine Interface HMI: Human-Machine Interface
LC := Local Controller LC: Local Controller
Figure 4: BAS architecture Figure 4: BAS Architecture
There are typically two layers of network in a BAS. The upper one is There are typically two layers of a network in a BAS. The upper
called the Management Network and the lower one is called the Field layer is called the management network, and the lower layer is called
Network. In management networks an IP-based communication protocol the field network. In management networks, an IP-based communication
is used, while in field networks non-IP based communication protocols protocol is used, while in field networks, non-IP-based communication
("field protocols") are mainly used. Field networks have specific protocols ("field protocols") are mainly used. Field networks have
timing requirements, whereas management networks can be best-effort. specific timing requirements, whereas management networks can be best
effort.
A Human Machine Interface (HMI) is typically a desktop PC used by An HMI is typically a desktop PC used by operators to monitor and
operators to monitor and display device states, send device control display device states, send device control commands to Local
commands to Local Controllers (LCs), and configure building schedules Controllers (LCs), and configure building schedules (for example,
(for example "turn off all room lights in the building at 10:00 PM"). "turn off all room lights in the building at 10:00 PM").
A Building Management Server (BMS) performs the following operations. A building management server (BMS) performs the following operations.
o Collect and store device states from LCs at regular intervals. o Collects and stores device states from LCs at regular intervals.
o Send control values to LCs according to a building schedule. o Sends control values to LCs according to a building schedule.
o Send an alarm signal to operators if it detects abnormal devices o Sends an alarm signal to operators if it detects abnormal device
states. states.
The BMS and HMI communicate with LCs via IP-based "management The BMS and HMI communicate with LCs via IP-based "management
protocols" (see standards [bacnetip], [knx]). protocols" (see standards [BACnet-IP] and [KNX]).
A LC is typically a Programmable Logic Controller (PLC) which is An LC is typically a Programmable Logic Controller (PLC) that is
connected to several tens or hundreds of devices using "field connected to several tens or hundreds of devices using "field
protocols". An LC performs the following kinds of operations: protocols". An LC performs the following kinds of operations:
o Measure device states and provide the information to BMS or HMI. o Measures device states and provides the information to a BMS
or HMI.
o Send control values to devices, unilaterally or as part of a o Sends control values to devices, unilaterally or as part of a
feedback control loop. feedback control loop.
There are many field protocols used at the time of this writing; some At the time of this writing, many field protocols are in use; some
are standards-based and others are proprietary (see standards are standards-based protocols, and others are proprietary (see
[lontalk], [modbus], [profibus] and [flnet]). The result is that standards [LonTalk], [MODBUS], [PROFIBUS], and [FL-net]). The result
BASs have multiple MAC/PHY modules and interfaces. This makes BASs is that BASs have multiple MAC/PHY modules and interfaces. This
more expensive, slower to develop, and can result in "vendor lock-in" makes BASs more expensive and slower to develop and can result in
with multiple types of management applications. "vendor lock-in" with multiple types of management applications.
4.2.2. BAS Deployment Model 4.2.2. BAS Deployment Model
An example BAS for medium or large buildings is shown in Figure 5. An example BAS for medium or large buildings is shown in Figure 5.
The physical layout spans multiple floors, and there is a monitoring The physical layout spans multiple floors and includes a monitoring
room where the BAS management entities are located. Each floor will room where the BAS management entities are located. Each floor will
have one or more LCs depending upon the number of devices connected have one or more LCs, depending on the number of devices connected to
to the field network. the field network.
+--------------------------------------------------+ +--------------------------------------------------+
| Floor 3 | | Floor 3 |
| +----LC~~~~+~~~~~+~~~~~+ | | +----LC~~~~+~~~~~+~~~~~+ |
| | | | | | | | | | | |
| | Dev Dev Dev | | | Dev Dev Dev |
| | | | | |
|--- | ------------------------------------------| |--- | ------------------------------------------|
| | Floor 2 | | | Floor 2 |
| +----LC~~~~+~~~~~+~~~~~+ Field Network | | +----LC~~~~+~~~~~+~~~~~+ Field Network |
skipping to change at page 39, line 28 skipping to change at page 44, line 36
| | Floor 1 | | | Floor 1 |
| +----LC~~~~+~~~~~+~~~~~+ +-----------------| | +----LC~~~~+~~~~~+~~~~~+ +-----------------|
| | | | | | Monitoring Room | | | | | | | Monitoring Room |
| | Dev Dev Dev | | | | Dev Dev Dev | |
| | | BMS HMI | | | | BMS HMI |
| | Management Network | | | | | | Management Network | | | |
| +--------------------------------+-----+ | | +--------------------------------+-----+ |
| | | | | |
+--------------------------------------------------+ +--------------------------------------------------+
Figure 5: BAS Deployment model for Medium/Large Buildings Figure 5: BAS Deployment Model for Medium/Large Buildings
Each LC is connected to the monitoring room via the Management Each LC is connected to the monitoring room via the management
network, and the management functions are performed within the network, and the management functions are performed within the
building. In most cases, fast Ethernet (e.g. 100BASE-T) is used for building. In most cases, Fast Ethernet (e.g., 100BASE-T) is used for
the management network. Since the management network is non- the management network. Since the management network is not a
realtime, use of Ethernet without quality of service is sufficient real-time network, the use of Ethernet without QoS is sufficient for
for today's deployment. today's deployments.
In the field network a variety of physical interfaces such as RS232C Many physical interfaces used in field networks have specific timing
and RS485 are used, which have specific timing requirements. Thus if requirements -- for example, RS232C and RS485. Thus, if a field
a field network is to be replaced with an Ethernet or wireless network is to be replaced with an Ethernet or wireless network, such
network, such networks must support time-critical deterministic networks must support time-critical deterministic flows.
flows.
In Figure 6, another deployment model is presented in which the Figure 6 shows another deployment model, in which the management
management system is hosted remotely. This is becoming popular for system is hosted remotely. This model is becoming popular for small
small office and residential buildings in which a standalone offices and residential buildings, in which a standalone monitoring
monitoring system is not cost-effective. system is not cost effective.
+---------------+ +---------------+
| Remote Center | | Remote Center |
| | | |
| BMS HMI | | BMS HMI |
+------------------------------------+ | | | | +------------------------------------+ | | | |
| Floor 2 | | +---+---+ | | Floor 2 | | +---+---+ |
| +----LC~~~~+~~~~~+ Field Network| | | | | +----LC~~~~+~~~~~+ Field Network| | | |
| | | | | | Router | | | | | | | Router |
| | Dev Dev | +-------|-------+ | | Dev Dev | +-------|-------+
skipping to change at page 40, line 26 skipping to change at page 45, line 31
| | Floor 1 | | | | Floor 1 | |
| +----LC~~~~+~~~~~+ | | | +----LC~~~~+~~~~~+ | |
| | | | | | | | | | | |
| | Dev Dev | | | | Dev Dev | |
| | | | | | | |
| | Management Network | WAN | | | Management Network | WAN |
| +------------------------Router-------------+ | +------------------------Router-------------+
| | | |
+------------------------------------+ +------------------------------------+
Figure 6: Deployment model for Small Buildings Figure 6: Deployment Model for Small Buildings
Some interoperability is possible today in the Management Network, Some interoperability is possible in today's management networks but
but not in today's field networks due to their non-IP-based design. is not possible in today's field networks due to their non-IP-based
design.
4.2.3. Use Cases for Field Networks 4.2.3. Use Cases for Field Networks
Below are use cases for Environmental Monitoring, Fire Detection, and Below are use cases for environmental monitoring, fire detection, and
Feedback Control, and their implications for field network feedback control, and their implications for field network
performance. performance.
4.2.3.1. Environmental Monitoring 4.2.3.1. Environmental Monitoring
The BMS polls each LC at a maximum measurement interval of 100ms (for The BMS polls each LC at a maximum measurement interval of 100 ms
example to draw a historical chart of 1 second granularity with a 10x (for example, to draw a historical chart of 1-second granularity with
sampling interval) and then performs the operations as specified by a 10x sampling interval) and then performs the operations as
the operator. Each LC needs to measure each of its several hundred specified by the operator. Each LC needs to measure each of its
sensors once per measurement interval. Latency is not critical in several hundred sensors once per measurement interval. Latency is
this scenario as long as all sensor values are completed in the not critical in this scenario as long as all sensor value
measurement interval. Availability is expected to be 99.999 %. measurements are completed within the measurement interval.
Availability is expected to be 99.999%.
4.2.3.2. Fire Detection 4.2.3.2. Fire Detection
On detection of a fire, the BMS must stop the HVAC, close the fire On detection of a fire, the BMS must stop the HVAC, close the fire
shutters, turn on the fire sprinklers, send an alarm, etc. There are shutters, turn on the fire sprinklers, send an alarm, etc. There are
typically ~10s of sensors per LC that BMS needs to manage. In this typically tens of fire sensors per LC that the BMS needs to manage.
scenario the measurement interval is 10-50ms, the communication delay In this scenario, the measurement interval is 10-50 ms, the
is 10ms, and the availability must be 99.9999 %. communication delay is 10 ms, and the availability must be 99.9999%.
4.2.3.3. Feedback Control 4.2.3.3. Feedback Control
BAS systems utilize feedback control in various ways; the most time- BASs utilize feedback control in various ways; the most time-critical
critial is control of DC motors, which require a short feedback is control of DC motors, which require a short feedback interval
interval (1-5ms) with low communication delay (10ms) and jitter (1-5 ms) with low communication delay (10 ms) and jitter (1 ms). The
(1ms). The feedback interval depends on the characteristics of the feedback interval depends on the characteristics of the device and on
device and a target quality of control value. There are typically the requirements for the control values. There are typically tens of
~10s of such devices per LC. feedback sensors per LC.
Communication delay is expected to be less than 10ms, jitter less Communication delay is expected to be less than 10 ms and jitter less
than 1ms while the availability must be 99.9999% . than 1 ms, while the availability must be 99.9999%.
4.2.4. Security Considerations 4.2.4. BAS Security Considerations
When BAS field networks were developed it was assumed that the field When BAS field networks were developed, it was assumed that the field
networks would always be physically isolated from external networks networks would always be physically isolated from external networks;
and therefore security was not a concern. In today's world many BASs therefore, security was not a concern. In today's world, many BASs
are managed remotely and are thus connected to shared IP networks and are managed remotely and are thus connected to shared IP networks;
so security is definitely a concern, yet security features are not therefore, security is a definite concern. Note, however, that
available in the majority of BAS field network deployments . security features are not currently available in the majority of BAS
field network deployments.
The management network, being an IP-based network, has the protocols The management network, being an IP-based network, has the protocols
available to enable network security, but in practice many BAS available to enable network security, but in practice many BASs do
systems do not implement even the available security features such as not implement even such available security features as device
device authentication or encryption for data in transit. authentication or encryption for data in transit.
4.3. BAS Future 4.3. BASs in the Future
In the future more fine-grained environmental monitoring and lower In the future, lower energy consumption and environmental monitoring
energy consumption will emerge which will require more sensors and that is more fine-grained will emerge; these will require more
devices, thus requiring larger and more complex building networks. sensors and devices, thus requiring larger and more-complex building
networks.
Building networks will be connected to or converged with other Building networks will be connected to or converged with other
networks (Enterprise network, Home network, and Internet). networks (enterprise networks, home networks, and the Internet).
Therefore better facilities for network management, control, Therefore, better facilities for network management, control,
reliability and security are critical in order to improve resident reliability, and security are critical in order to improve resident
and operator convenience and comfort. For example the ability to and operator convenience and comfort. For example, the ability to
monitor and control building devices via the internet would enable monitor and control building devices via the Internet would enable
(for example) control of room lights or HVAC from a resident's (for example) control of room lights or HVAC from a resident's
desktop PC or phone application. desktop PC or phone application.
4.4. BAS Asks 4.4. BAS Requests to the IETF
The community would like to see an interoperable protocol The community would like to see an interoperable protocol
specification that can satisfy the timing, security, availability and specification that can satisfy the timing, security, availability,
QoS constraints described above, such that the resulting converged and QoS constraints described above, such that the resulting
network can replace the disparate field networks. Ideally this converged network can replace the disparate field networks. Ideally,
connectivity could extend to the open Internet. this connectivity could extend to the open Internet.
This would imply an architecture that can guarantee This would imply an architecture that can guarantee
o Low communication delays (from <10ms to 100ms in a network of o Low communication delays (from <10 ms to 100 ms in a network of
several hundred devices) several hundred devices)
o Low jitter (< 1 ms) o Low jitter (<1 ms)
o Tight feedback intervals (1ms - 10ms) o Tight feedback intervals (1-10 ms)
o High network availability (up to 99.9999% ) o High network availability (up to 99.9999%)
o Availability of network data in disaster scenario o Availability of network data in disaster scenarios
o Authentication between management and field devices (both local o Authentication between management devices and field devices (both
and remote) local and remote)
o Integrity and data origin authentication of communication data o Integrity and data origin authentication of communication data
between field and management devices between management devices and field devices
o Confidentiality of data when communicated to a remote device o Confidentiality of data when communicated to a remote device
5. Wireless for Industrial Applications 5. Wireless for Industrial Applications
5.1. Use Case Description 5.1. Use Case Description
Wireless networks are useful for industrial applications, for example Wireless networks are useful for industrial applications -- for
when portable, fast-moving or rotating objects are involved, and for example, (1) when portable, fast-moving, or rotating objects are
the resource-constrained devices found in the Internet of Things involved and (2) for the resource-constrained devices found in the
(IoT). Internet of Things (IoT).
Such network-connected sensors, actuators, control loops (etc.) Such network-connected sensors, actuators, control loops, etc.
typically require that the underlying network support real-time typically require that the underlying network support real-time QoS,
quality of service (QoS), as well as specific classes of other as well as such specific network properties as reliability,
network properties such as reliability, redundancy, and security. redundancy, and security.
These networks may also contain very large numbers of devices, for These networks may also contain very large numbers of devices -- for
example for factories, "big data" acquisition, and the IoT. Given example, for factories, "big data" acquisition, and the IoT. Given
the large numbers of devices installed, and the potential the large numbers of devices installed and the potential
pervasiveness of the IoT, this is a huge and very cost-sensitive pervasiveness of the IoT, this is a huge and very cost-sensitive
market such that small cost reductions can save large amounts of market such that small cost reductions can save large amounts of
money. money.
5.1.1. Network Convergence using 6TiSCH 5.1.1. Network Convergence Using 6TiSCH
Some wireless network technologies support real-time QoS, and are Some wireless network technologies support real-time QoS and are thus
thus useful for these kinds of networks, but others do not. useful for these kinds of networks, but others do not.
This use case focuses on one specific wireless network technology This use case focuses on one specific wireless network technology
which provides the required deterministic QoS, which is "IPv6 over that provides the required deterministic QoS: "IPv6 over the TSCH
the TSCH mode of IEEE 802.15.4e" (6TiSCH, where TSCH stands for mode of IEEE 802.15.4e" (6TiSCH, where "TSCH" stands for
"Time-Slotted Channel Hopping", see [I-D.ietf-6tisch-architecture], "Time-Slotted Channel Hopping"; see [Arch-for-6TiSCH], [IEEE-802154],
[IEEE802154], [IEEE802154e], and [RFC7554]). and [RFC7554]).
There are other deterministic wireless busses and networks available There are other deterministic wireless buses and networks available
today, however they are imcompatible with each other, and today; however, they are incompatible with each other and with IP
incompatible with IP traffic (for example [ISA100], [WirelessHART]). traffic (for example, see [ISA100] and [WirelessHART]).
Thus the primary goal of this use case is to apply 6TiSCH as a Thus, the primary goal of this use case is to apply 6TiSCH as a
converged IP- and standards-based wireless network for industrial converged IP-based and standards-based wireless network for
applications, i.e. to replace multiple proprietary and/or industrial applications, i.e., to replace multiple proprietary and/or
incompatible wireless networking and wireless network management incompatible wireless networking and wireless network management
standards. standards.
5.1.2. Common Protocol Development for 6TiSCH 5.1.2. Common Protocol Development for 6TiSCH
Today there are a number of protocols required by 6TiSCH which are Today, there are a number of protocols required by 6TiSCH that are
still in development, and a second intent of this use case is to still in development. Another goal of this use case is to highlight
highlight the ways in which these "missing" protocols share goals in the ways in which these "missing" protocols share goals in common
common with DetNet. Thus it is possible that some of the protocol with DetNet. Thus, it is possible that some of the protocol
technology developed for DetNet will also be applicable to 6TiSCH. technology developed for DetNet will also be applicable to 6TiSCH.
These protocol goals are identified here, along with their These protocol goals are identified here, along with their
relationship to DetNet. It is likely that ultimately the resulting relationship to DetNet. It is likely that ultimately the resulting
protocols will not be identical, but will share design principles protocols will not be identical but will share design principles that
which contribute to the eficiency of enabling both DetNet and 6TiSCH. contribute to the efficiency of enabling both DetNet and 6TiSCH.
One such commonality is that although at a different time scale, in One such commonality is that -- although on a different time scale --
both TSN [IEEE802.1TSNTG] and TSCH a packet crosses the network from in both TSN [IEEE-8021TSNTG] and TSCH, a packet that crosses the
node to node follows a precise schedule, as a train that leaves network from node to node follows a precise schedule, as does a train
intermediate stations at precise times along its path. This kind of that leaves intermediate stations at precise times along its path.
operation reduces collisions, saves energy, and enables engineering This kind of operation reduces collisions, saves energy, and enables
the network for deterministic properties. engineering of the network for deterministic properties.
Another commonality is remote monitoring and scheduling management of Another commonality is remote monitoring and scheduling management of
a TSCH network by a Path Computation Element (PCE) and Network a TSCH network by a Path Computation Element (PCE) and Network
Management Entity (NME). The PCE/NME manage timeslots and device Management Entity (NME). The PCE and NME manage timeslots and device
resources in a manner that minimizes the interaction with and the resources in a manner that minimizes the interaction with, and the
load placed on resource-constrained devices. For example, a tiny IoT load placed on, resource-constrained devices. For example, a tiny
device may have just enough buffers to store one or a few IPv6 IoT device may have just enough buffers to store one or a few IPv6
packets, and will have limited bandwidth between peers such that it packets; it will have limited bandwidth between peers such that it
can maintain only a small amount of peer information, and will not be can maintain only a small amount of peer information, and it will not
able to store many packets waiting to be forwarded. It is be able to store many packets waiting to be forwarded. It is
advantageous then for it to only be required to carry out the advantageous, then, for the IoT device to only be required to carry
specific behavior assigned to it by the PCE/NME (as opposed to out the specific behavior assigned to it by the PCE and NME (as
maintaining its own IP stack, for example). opposed to maintaining its own IP stack, for example).
It is possible that there will be some peer-to-peer communication, It is possible that there will be some peer-to-peer communication;
for example the PCE may communicate only indirectly with some devices for example, the PCE may communicate only indirectly with some
in order to enable hierarchical configuration of the system. devices in order to enable hierarchical configuration of the system.
6TiSCH depends on [PCE] and [I-D.ietf-detnet-architecture]. 6TiSCH depends on [PCE] and [DetNet-Arch].
6TiSCH also depends on the fact that DetNet will maintain consistency 6TiSCH also depends on the fact that DetNet will maintain consistency
with [IEEE802.1TSNTG]. with [IEEE-8021TSNTG].
5.2. Wireless Industrial Today 5.2. Wireless Industrial Today
Today industrial wireless is accomplished using multiple Today, industrial wireless technology ("wireless industrial") is
deterministic wireless networks which are incompatible with each accomplished using multiple deterministic wireless networks that are
other and with IP traffic. incompatible with each other and with IP traffic.
6TiSCH is not yet fully specified, so it cannot be used in today's 6TiSCH is not yet fully specified, so it cannot be used in today's
applications. applications.
5.3. Wireless Industrial Future 5.3. Wireless Industrial in the Future
5.3.1. Unified Wireless Network and Management 5.3.1. Unified Wireless Networks and Management
DetNet and 6TiSCH together can enable converged transport of DetNet and 6TiSCH together can enable converged transport of
deterministic and best-effort traffic flows between real-time deterministic and best-effort traffic flows between real-time
industrial devices and wide area networks via IP routing. A high industrial devices and WANs via IP routing. A high-level view of
level view of a basic such network is shown in Figure 7. this type of basic network is shown in Figure 7.
---+-------- ............ ------------ ---+-------- ............ ------------
| External Network | | External Network |
| +-----+ | +-----+
+-----+ | NME | +-----+ | NME |
| | LLN Border | | | | LLN Border | |
| | router +-----+ | | Router +-----+
+-----+ +-----+
o o o o o o
o o o o o o o o
o o LLN o o o o o LLN o o o
o o o o o o o o
o o
LLN: Low-Power and Lossy Network
Figure 7: Basic 6TiSCH Network Figure 7: Basic 6TiSCH Network
Figure 8 shows a backbone router federating multiple synchronized Figure 8 shows a backbone router federating multiple synchronized
6TiSCH subnets into a single subnet connected to the external 6TiSCH subnets into a single subnet connected to the external
network. network.
---+-------- ............ ------------ ---+-------- ............ ------------
| External Network | | External Network |
| +-----+ | +-----+
| +-----+ | NME | | +-----+ | NME |
+-----+ | +-----+ | | +-----+ | +-----+ | |
| | Router | | PCE | +-----+ | | Router | | PCE | +-----+
| | +--| | | | +--| |
+-----+ +-----+ +-----+ +-----+
| | | |
| Subnet Backbone | | Subnet Backbone |
+--------------------+------------------+ +--------------------+------------------+
| | | | | |
+-----+ +-----+ +-----+ +-----+ +-----+ +-----+
| | Backbone | | Backbone | | Backbone | | Backbone | | Backbone | | Backbone
o | | router | | router | | router o | | Router | | Router | | Router
+-----+ +-----+ +-----+ +-----+ +-----+ +-----+
o o o o o o o o o o
o o o o o o o o o o o o o o o o o o o o o o
o o o LLN o o o o o o o LLN o o o o
o o o o o o o o o o o o o o o o o o o o o o o o
Figure 8: Extended 6TiSCH Network Figure 8: Extended 6TiSCH Network
The backbone router must ensure end-to-end deterministic behavior The backbone router must ensure end-to-end deterministic behavior
between the LLN and the backbone. This should be accomplished in between the LLN and the backbone. This should be accomplished in
conformance with the work done in [I-D.ietf-detnet-architecture] with conformance with the work done in [DetNet-Arch] with respect to
respect to Layer-3 aspects of deterministic networks that span Layer 3 aspects of deterministic networks that span multiple Layer 2
multiple Layer-2 domains. domains.
The PCE must compute a deterministic path end-to-end across the TSCH The PCE must compute a deterministic path end to end across the TSCH
network and IEEE802.1 TSN Ethernet backbone, and DetNet protocols are network and IEEE 802.1 TSN Ethernet backbone, and DetNet protocols
expected to enable end-to-end deterministic forwarding. are expected to enable end-to-end deterministic forwarding.
5.3.1.1. PCE and 6TiSCH ARQ Retries
6TiSCH uses the Automatic Repeat reQuest (ARQ) mechanism
[IEEE-802154] to provide higher reliability of packet delivery. ARQ
is related to Packet Replication and Elimination (PRE) because there
are two independent paths for packets to arrive at the destination.
If an expected packet does not arrive on one path, then it checks for
the packet on the second path.
Although to date this mechanism is only used by wireless networks,
this technique might be appropriate for DetNet, and aspects of the
enabling protocol could therefore be co-developed.
For example, in Figure 9, a track is laid out from a field device in
a 6TiSCH network to an IoT gateway that is located on an IEEE 802.1
TSN backbone.
+-----+ +-----+
| IoT | | IoT |
| G/W | | G/W |
+-----+ +-----+
^ <---- Elimination ^ <---- Elimination
| | | |
Track branch | | Track Branch | |
+-------+ +--------+ Subnet Backbone +-------+ +--------+ Subnet Backbone
| | | |
+--|--+ +--|--+ +--|--+ +--|--+
| | | Backbone | | | Backbone | | | Backbone | | | Backbone
o | | | router | | | router o | | | Router | | | Router
+--/--+ +--|--+ +--/--+ +--|--+
o / o o---o----/ o o / o o---o----/ o
o o---o--/ o o o o o o o---o--/ o o o o o
o \ / o o LLN o o \ / o o LLN o
o v <---- Replication o v <---- Replication
o o
Figure 9: 6TiSCH Network with PRE Figure 9: 6TiSCH Network with PRE
5.3.1.1. PCE and 6TiSCH ARQ Retries In ARQ, the replication function in the field device sends a copy of
6TiSCH uses the IEEE802.15.4 Automatic Repeat-reQuest (ARQ) mechanism
to provide higher reliability of packet delivery. ARQ is related to
packet replication and elimination because there are two independent
paths for packets to arrive at the destination, and if an expected
packed does not arrive on one path then it checks for the packet on
the second path.
Although to date this mechanism is only used by wireless networks,
this may be a technique that would be appropriate for DetNet and so
aspects of the enabling protocol could be co-developed.
For example, in Figure 9, a Track is laid out from a field device in
a 6TiSCH network to an IoT gateway that is located on a IEEE802.1 TSN
backbone.
In ARQ the Replication function in the field device sends a copy of
each packet over two different branches, and the PCE schedules each each packet over two different branches, and the PCE schedules each
hop of both branches so that the two copies arrive in due time at the hop of both branches so that the two copies arrive in due time at the
gateway. In case of a loss on one branch, hopefully the other copy gateway. In the case of a loss on one branch, one hopes that the
of the packet still arrives within the allocated time. If two copies other copy of the packet will still arrive within the allocated time.
make it to the IoT gateway, the Elimination function in the gateway If two copies make it to the IoT gateway, the elimination function in
ignores the extra packet and presents only one copy to upper layers. the gateway ignores the extra packet and presents only one copy to
upper layers.
At each 6TiSCH hop along the Track, the PCE may schedule more than At each 6TiSCH hop along the track, the PCE may schedule more than
one timeSlot for a packet, so as to support Layer-2 retries (ARQ). one timeslot for a packet, so as to support Layer 2 retries (ARQ).
In deployments at the time of this writing, a TSCH Track does not At the time of this writing, a deployment's TSCH track does not
necessarily support PRE but is systematically multi-path. This means necessarily support PRE but is systematically multipath. This means
that a Track is scheduled so as to ensure that each hop has at least that a track is scheduled so as to ensure that each hop has at least
two forwarding solutions, and the forwarding decision is to try the two forwarding solutions. The forwarding decision will be to try the
preferred one and use the other in case of Layer-2 transmission preferred solution and use the other solution in the case of Layer 2
failure as detected by ARQ. transmission failure as detected by ARQ.
5.3.2. Schedule Management by a PCE 5.3.2. Schedule Management by a PCE
A common feature of 6TiSCH and DetNet is the action of a PCE to A common feature of 6TiSCH and DetNet is actions taken by a PCE when
configure paths through the network. Specifically, what is needed is configuring paths through the network. Specifically, what is needed
a protocol and data model that the PCE will use to get/set the is a protocol and data model that the PCE will use to get/set the
relevant configuration from/to the devices, as well as perform relevant configuration from/to the devices, as well as perform
operations on the devices. This protocol should be developed by operations on the devices. Specifically, both DetNet and 6TiSCH need
DetNet with consideration for its reuse by 6TiSCH. The remainder of to develop a protocol (and associated data model) that the PCE can
this section provides a bit more context from the 6TiSCH side. use to (1) get/set the relevant configuration from/to the devices and
(2) perform operations on the devices. These could be initially
developed by DetNet, with consideration for their reuse by 6TiSCH.
The remainder of this section provides a bit more context from the
6TiSCH side.
5.3.2.1. PCE Commands and 6TiSCH CoAP Requests 5.3.2.1. PCE Commands and 6TiSCH CoAP Requests
The 6TiSCH device does not expect to place the request for bandwidth The 6TiSCH device does not expect to place the request for bandwidth
between itself and another device in the network. Rather, an between itself and another device in the network. Rather, an
operation control system invoked through a human interface specifies operation control system invoked through a human interface specifies
the required traffic specification and the end nodes (in terms of the traffic requirements and the end nodes (in terms of latency and
latency and reliability). Based on this information, the PCE must reliability). Based on this information, the PCE must compute a path
compute a path between the end nodes and provision the network with between the end nodes and provision the network with per-flow state
per-flow state that describes the per-hop operation for a given that describes the per-hop operation for a given packet, the
packet, the corresponding timeslots, and the flow identification that corresponding timeslots, the flow identification that enables
enables recognizing that a certain packet belongs to a certain path, recognizing that a certain packet belongs to a certain path, etc.
etc.
For a static configuration that serves a certain purpose for a long For a static configuration that serves a certain purpose for a long
period of time, it is expected that a node will be provisioned in one period of time, it is expected that a node will be provisioned in one
shot with a full schedule, which incorporates the aggregation of its shot with a full schedule, i.e., a schedule that defines the behavior
behavior for multiple paths. 6TiSCH expects that the programing of of the node with respect to all data flows through that node. 6TiSCH
the schedule will be done over COAP as discussed in expects that the programming of the schedule will be done over the
[I-D.ietf-6tisch-coap]. Constrained Application Protocol (CoAP) as discussed in
[CoAP-6TiSCH].
6TiSCH expects that the PCE commands will be mapped back and forth 6TiSCH expects that the PCE commands will be mapped back and forth
into CoAP by a gateway function at the edge of the 6TiSCH network. into CoAP by a gateway function at the edge of the 6TiSCH network.
For instance, it is possible that a mapping entity on the backbone For instance, it is possible that a mapping entity on the backbone
transforms a non-CoAP protocol such as PCEP into the RESTful transforms a non-CoAP protocol such as the Path Computation Element
interfaces that the 6TiSCH devices support. This architecture will Communication Protocol (PCEP) into the RESTful interfaces that the
be refined to comply with DetNet [I-D.ietf-detnet-architecture] when 6TiSCH devices support. This architecture will be refined to comply
the work is formalized. Related information about 6TiSCH can be with DetNet [DetNet-Arch] when the work is formalized. Related
found at [I-D.ietf-6tisch-6top-interface] and RPL [RFC6550]. information about 6TiSCH can be found in [Interface-6TiSCH-6top] and
[RFC6550] ("RPL: IPv6 Routing Protocol for Low-Power and Lossy
Networks").
A protocol may be used to update the state in the devices during A protocol may be used to update the state in the devices during
runtime, for example if it appears that a path through the network runtime -- for example, if it appears that a path through the network
has ceased to perform as expected, but in 6TiSCH that flow was not has ceased to perform as expected, but in 6TiSCH that flow was not
designed and no protocol was selected. DetNet should define the designed and no protocol was selected. DetNet should define the
appropriate end-to-end protocols to be used in that case. The appropriate end-to-end protocols to be used in that case. The
implication is that these state updates take place once the system is implication is that these state updates take place once the system is
configured and running, i.e. they are not limited to the initial configured and running, i.e., they are not limited to the initial
communication of the configuration of the system. communication of the configuration of the system.
A "slotFrame" is the base object that a PCE would manipulate to A "slotFrame" is the base object that a PCE would manipulate to
program a schedule into an LLN node ([I-D.ietf-6tisch-architecture]). program a schedule into an LLN node [Arch-for-6TiSCH].
The PCE should read energy data from devices and compute paths that The PCE should read energy data from devices and compute paths that
will implement policies on how energy in devices is consumed, for will implement policies on how energy in devices is consumed -- for
instance to ensure that the spent energy does not exceeded the instance, to ensure that the spent energy does not exceed the
available energy over a period of time. Note: this statement implies available energy over a period of time. Note that this statement
that an extensible protocol for communicating device info to the PCE implies that an extensible protocol for communicating device
and enabling the PCE to act on it will be part of the DetNet information to the PCE and enabling the PCE to act on it will be part
architecture, however for subnets with specific protocols (e.g. of the DetNet architecture; however, for subnets with specific
CoAP) a gateway may be required. protocols (e.g., CoAP), a gateway may be required.
6TiSCH devices can discover their neighbors over the radio using a 6TiSCH devices can discover their neighbors over the radio using a
mechanism such as beacons, but even though the neighbor information mechanism such as beacons, but even though the neighbor information
is available in the 6TiSCH interface data model, 6TiSCH does not is available in the 6TiSCH interface data model, 6TiSCH does not
describe a protocol to proactively push the neighborhood information describe a protocol to proactively push the neighbor information to a
to a PCE. DetNet should define such a protocol; one possible design PCE. DetNet should define such a protocol; one possible design
alternative is that it could operate over CoAP, alternatively it alternative is that it could operate over CoAP. Alternatively, it
could be converted to/from CoAP by a gateway. Such a protocol could could be converted to/from CoAP by a gateway. Such a protocol could
carry multiple metrics, for example similar to those used for RPL carry multiple metrics -- for example, metrics similar to those used
operations [RFC6551] for RPL operations [RFC6551].
5.3.2.2. 6TiSCH IP Interface 5.3.2.2. 6TiSCH IP Interface
"6top" ([I-D.wang-6tisch-6top-sublayer]) is a logical link control Protocol translation between the TSCH MAC layer and IP is
sitting between the IP layer and the TSCH MAC layer which provides accomplished via the "6top" sublayer [Sublayer-6TiSCH-6top]. The
the link abstraction that is required for IP operations. The 6top 6top data model and management interfaces are further discussed in
data model and management interfaces are further discussed in [Interface-6TiSCH-6top] and [CoAP-6TiSCH].
[I-D.ietf-6tisch-6top-interface] and [I-D.ietf-6tisch-coap].
An IP packet that is sent along a 6TiSCH path uses the Differentiated An IP packet that is sent along a 6TiSCH path uses a differentiated
Services Per-Hop-Behavior Group called Deterministic Forwarding, as services Per-Hop Behavior Group (PHB) called "deterministic
described in [I-D.svshah-tsvwg-deterministic-forwarding]. forwarding", as described in [Det-Fwd-PHB].
5.3.3. 6TiSCH Security Considerations 5.3.3. 6TiSCH Security Considerations
On top of the classical requirements for protection of control In addition to the classical requirements for protection of control
signaling, it must be noted that 6TiSCH networks operate on limited signaling, it must be noted that 6TiSCH networks operate on limited
resources that can be depleted rapidly in a DoS attack on the system, resources that can be depleted rapidly in a DoS attack on the system
for instance by placing a rogue device in the network, or by -- for instance, by placing a rogue device in the network or by
obtaining management control and setting up unexpected additional obtaining management control and setting up unexpected additional
paths. paths.
5.4. Wireless Industrial Asks 5.4. Wireless Industrial Requests to the IETF
6TiSCH depends on DetNet to define: 6TiSCH depends on DetNet to define:
o Configuration (state) and operations for deterministic paths o Configuration (state) and operations for deterministic paths
o End-to-end protocols for deterministic forwarding (tagging, IP) o End-to-end protocols for deterministic forwarding (tagging, IP)
o Protocol for packet replication and elimination o A protocol for PRE
6. Cellular Radio 6. Cellular Radio
6.1. Use Case Description 6.1. Use Case Description
This use case describes the application of deterministic networking This use case describes the application of deterministic networking
in the context of cellular telecom transport networks. Important in the context of cellular telecom transport networks. Important
elements include time synchronization, clock distribution, and ways elements include time synchronization, clock distribution, and ways
of establishing time-sensitive streams for both Layer-2 and Layer-3 to establish time-sensitive streams for both Layer 2 and Layer 3
user plane traffic. user-plane traffic.
6.1.1. Network Architecture 6.1.1. Network Architecture
Figure 10 illustrates a 3GPP-defined cellular network architecture Figure 10 illustrates a 3GPP-defined cellular network architecture
typical at the time of this writing, which includes "Fronthaul", typical at the time of this writing. The architecture includes
"Midhaul" and "Backhaul" network segments. The "Fronthaul" is the "Fronthaul", "Midhaul", and "Backhaul" network segments. The
network connecting base stations (baseband processing units) to the "Fronthaul" is the network connecting base stations (Baseband Units
remote radio heads (antennas). The "Midhaul" is the network inter- (BBUs)) to the Remote Radio Heads (RRHs) (also referred to here as
connecting base stations (or small cell sites). The "Backhaul" is "antennas"). The "Midhaul" is the network that interconnects base
the network or links connecting the radio base station sites to the stations (or small-cell sites). The "Backhaul" is the network or
network controller/gateway sites (i.e. the core of the 3GPP cellular links connecting the radio base station sites to the network
controller/gateway sites (i.e., the core of the 3GPP cellular
network). network).
In Figure 10 "eNB" ("E-UTRAN Node B") is the hardware that is Y (RRHs (antennas))
connected to the mobile phone network which communicates directly
with mobile handsets ([TS36300]).
Y (remote radio heads (antennas))
\ \
Y__ \.--. .--. +------+ Y__ \.--. .--. +------+
\_( `. +---+ _(Back`. | 3GPP | \_( `. +---+ _( `. | 3GPP |
Y------( Front )----|eNB|----( Haul )----| core | Y------( Front- )----|eNB|----( Back- )------| core |
( ` .Haul ) +---+ ( ` . ) ) | netw | ( ` .haul ) +---+ ( ` .haul) ) | netw |
/`--(___.-' \ `--(___.-' +------+ /`--(___.-' \ `--(___.-' +------+
Y_/ / \.--. \ Y_/ / \.--. \
Y_/ _( Mid`. \ Y_/ _(Mid-`. \
( Haul ) \ ( haul ) \
( ` . ) ) \ ( ` . ) ) \
`--(___.-'\_____+---+ (small cell sites) `--(___.-'\_____+---+ (small-cell sites)
\ |SCe|__Y \ |SCe|__Y
+---+ +---+ +---+ +---+
Y__|eNB|__Y Y__|eNB|__Y
+---+ +---+
Y_/ \_Y ("local" radios) Y_/ \_Y ("local" radios)
Figure 10: Generic 3GPP-based Cellular Network Architecture Figure 10: Generic 3GPP-Based Cellular Network Architecture
In Figure 10, "eNB" ("E-UTRAN Node B") is the hardware that is
connected to the mobile phone network and enables the mobile phone
network to communicate with mobile handsets [TS36300]. ("E-UTRAN"
stands for "Evolved Universal Terrestrial Radio Access Network".)
6.1.2. Delay Constraints 6.1.2. Delay Constraints
The available processing time for Fronthaul networking overhead is The available processing time for Fronthaul networking overhead is
limited to the available time after the baseband processing of the limited to the available time after the baseband processing of the
radio frame has completed. For example in Long Term Evolution (LTE) radio frame has completed. For example, in Long Term Evolution (LTE)
radio, processing of a radio frame is allocated 3ms but typically the radio, 3 ms is allocated for the processing of a radio frame, but
processing uses most of it, allowing only a small fraction to be used typically the baseband processing uses most of it, allowing only a
by the Fronthaul network (e.g. up to 250us one-way delay, though the small fraction to be used by the Fronthaul network. In this example,
existing spec ([NGMN-fronth]) supports delay only up to 100us). This out of 3 ms, the maximum time allocated to the Fronthaul network for
ultimately determines the distance the remote radio heads can be one-way delay is 250 us, and the existing specification [NGMN-Fronth]
located from the base stations (e.g., 100us equals roughly 20 km of specifies a maximum delay of only 100 us. This ultimately determines
optical fiber-based transport). Allocation options of the available the distance the RRHs can be located from the base stations (e.g.,
time budget between processing and transport are under heavy 100 us equals roughly 20 km of optical fiber-based transport).
discussions in the mobile industry. Allocation options regarding the available time budget between
processing and transport are currently undergoing heavy discussion in
the mobile industry.
For packet-based transport the allocated transport time (e.g. CPRI For packet-based transport, the allocated transport time between the
would allow for 100us delay [CPRI]) is consumed by all nodes and RRH and the BBU is consumed by node processing, buffering, and
buffering between the remote radio head and the baseband processing distance-incurred delay. An example of the allocated transport time
unit, plus the distance-incurred delay. is 100 us (from the Common Public Radio Interface [CPRI]).
The baseband processing time and the available "delay budget" for the The baseband processing time and the available "delay budget" for the
fronthaul is likely to change in the forthcoming "5G" due to reduced Fronthaul is likely to change in the forthcoming "5G" due to reduced
radio round trip times and other architectural and service radio round-trip times and other architectural and service
requirements [NGMN]. requirements [NGMN].
The transport time budget, as noted above, places limitations on the The transport time budget, as noted above, places limitations on the
distance that remote radio heads can be located from base stations distance that RRHs can be located from base stations (i.e., the link
(i.e. the link length). In the above analysis, the entire transport length). In the above analysis, it is assumed that the entire
time budget is assumed to be available for link propagation delay. transport time budget is available for link propagation delay.
However the transport time budget can be broken down into three However, the transport time budget can be broken down into three
components: scheduling /queueing delay, transmission delay, and link components: scheduling/queuing delay, transmission delay, and link
propagation delay. Using today's Fronthaul networking technology, propagation delay. Using today's Fronthaul networking technology,
the queuing, scheduling and transmission components might become the the queuing, scheduling, and transmission components might become the
dominant factors in the total transport time rather than the link dominant factors in the total transport time, rather than the link
propagation delay. This is especially true in cases where the propagation delay. This is especially true in cases where the
Fronthaul link is relatively short and it is shared among multiple Fronthaul link is relatively short and is shared among multiple
Fronthaul flows, for example in indoor and small cell networks, Fronthaul flows -- for example, in indoor and small-cell networks,
massive MIMO antenna networks, and split Fronthaul architectures. massive Multiple Input Multiple Output (MIMO) antenna networks, and
split Fronthaul architectures.
DetNet technology can improve this application by controlling and DetNet technology can improve Fronthaul networks by controlling and
reducing the time required for the queuing, scheduling and reducing the time required for the queuing, scheduling, and
transmission operations by properly assigning the network resources, transmission operations by properly assigning network resources, thus
thus leaving more of the transport time budget available for link (1) leaving more of the transport time budget available for link
propagation, and thus enabling longer link lengths. However, link propagation and (2) enabling longer link lengths. However, link
length is usually a given parameter and is not a controllable network length is usually a predetermined parameter and is not a controllable
parameter, since RRH and BBU sights are usually located in network parameter, since RRH and BBU sites are usually located in
predetermined locations. However, the number of antennas in an RRH predetermined locations. However, the number of antennas in an RRH
sight might increase for example by adding more antennas, increasing site might increase -- for example, by adding more antennas,
the MIMO capability of the network or support of massive MIMO. This increasing the MIMO capability of the network, or adding support for
means increasing the number of the fronthaul flows sharing the same massive MIMO. This means increasing the number of Fronthaul flows
fronthaul link. DetNet can now control the bandwidth assignment of sharing the same Fronthaul link. DetNet can now control the
the fronthaul link and the scheduling of fronthaul packets over this bandwidth assignment of the Fronthaul link and the scheduling of
link and provide adequate buffer provisioning for each flow to reduce Fronthaul packets over this link and can provide adequate buffer
the packet loss rate. provisioning for each flow to reduce the packet loss rate.
Another way in which DetNet technology can aid Fronthaul networks is Another way in which DetNet technology can aid Fronthaul networks is
by providing effective isolation from best-effort (and other classes by providing effective isolation between flows -- for example,
of) traffic, which can arise as a result of network slicing in 5G between flows originating in different slices within a network-sliced
networks where Fronthaul traffic generated in different network 5G network. Note, however, that this isolation applies to DetNet
slices might have differing performance requirements. DetNet flows for which resources have been preallocated, i.e., it does not
technology can also dynamically control the bandwidth assignment, apply to best-effort flows within a DetNet. DetNet technology can
scheduling and packet forwarding decisions and the buffer also dynamically control the bandwidth-assignment, scheduling, and
provisioning of the Fronthaul flows to guarantee the end-to-end delay packet-forwarding decisions, as well as the buffer provisioning of
of the Fronthaul packets and minimize the packet loss rate. the Fronthaul flows to guarantee the end-to-end delay of the
Fronthaul packets and minimize the packet loss rate.
[METIS] documents the fundamental challenges as well as overall [METIS] documents the fundamental challenges as well as overall
technical goals of the future 5G mobile and wireless system as the technical goals of the future 5G mobile and wireless systems as the
starting point. These future systems should support much higher data starting point. These future systems should support much higher data
volumes and rates and significantly lower end-to-end latency for 100x volumes and rates and significantly lower end-to-end latency for 100x
more connected devices (at similar cost and energy consumption levels more connected devices (at cost and energy-consumption levels similar
as today's system). to today's systems).
For Midhaul connections, delay constraints are driven by Inter-Site For Midhaul connections, delay constraints are driven by inter-site
radio functions like Coordinated Multipoint Processing (CoMP, see radio functions such as Coordinated Multi-Point (CoMP) processing
[CoMP]). CoMP reception and transmission is a framework in which (see [CoMP]). CoMP reception and transmission constitute a framework
multiple geographically distributed antenna nodes cooperate to in which multiple geographically distributed antenna nodes cooperate
improve the performance of the users served in the common cooperation to improve performance for the users served in the common cooperation
area. The design principal of CoMP is to extend single-cell to area. The design principle of CoMP is to extend single-cell-to-
multi-UE (User Equipment) transmission to a multi-cell-to-multi-UEs multi-UE (User Equipment) transmission to a multi-cell-to-multi-UE
transmission by base station cooperation. transmission via cooperation among base stations.
CoMP has delay-sensitive performance parameters, which are "midhaul CoMP has delay-sensitive performance parameters: "Midhaul latency"
latency" and "CSI (Channel State Information) reporting and and "CSI (Channel State Information) reporting and accuracy". The
accuracy". The essential feature of CoMP is signaling between eNBs, essential feature of CoMP is signaling between eNBs, so Midhaul
so Midhaul latency is the dominating limitation of CoMP performance. latency is the dominating limitation of CoMP performance. Generally,
Generally, CoMP can benefit from coordinated scheduling (either CoMP can benefit from coordinated scheduling (either distributed or
distributed or centralized) of different cells if the signaling delay centralized) of different cells if the signaling delay between eNBs
between eNBs is within 1-10ms. This delay requirement is both rigid is within 1-10 ms. This delay requirement is both rigid and
and absolute because any uncertainty in delay will degrade the absolute, because any uncertainty in delay will degrade performance
performance significantly. significantly.
Inter-site CoMP is one of the key requirements for 5G and is also a Inter-site CoMP is one of the key requirements for 5G and is also a
goal for 4.5G network architecture. goal for 4.5G network architectures.
6.1.3. Time Synchronization Constraints 6.1.3. Time-Synchronization Constraints
Fronthaul time synchronization requirements are given by [TS25104], Fronthaul time-synchronization requirements are given by [TS25104],
[TS36104], [TS36211], and [TS36133]. These can be summarized for the [TS36104], [TS36211], and [TS36133]. These can be summarized for the
3GPP LTE-based networks as: 3GPP LTE-based networks as:
Delay Accuracy: Delay accuracy:
+-8ns (i.e. +-1/32 Tc, where Tc is the UMTS Chip time of 1/3.84 +-8 ns (i.e., +-1/32 Tc, where Tc is the Universal Mobile
MHz) resulting in a round trip accuracy of +-16ns. The value is Telecommunications System (UMTS) Chip time of 1/3.84 MHz),
this low to meet the 3GPP Timing Alignment Error (TAE) measurement resulting in a round-trip accuracy of +-16 ns. The value is this
requirements. Note: performance guarantees of low nanosecond low in order to meet the 3GPP Timing Alignment Error (TAE)
values such as these are considered to be below the DetNet layer - measurement requirements. Note that performance guarantees of
it is assumed that the underlying implementation, e.g. the low-nanosecond values such as these are considered to be below the
hardware, will provide sufficient support (e.g. buffering) to DetNet layer -- it is assumed that the underlying implementation
enable this level of accuracy. These values are maintained in the (e.g., the hardware) will provide sufficient support (e.g.,
use case to give an indication of the overall application. buffering) to enable this level of accuracy. These values are
maintained in the use case to give an indication of the overall
application.
TAE:
TAE is problematic for Fronthaul networks and must be minimized.
If the transport network cannot guarantee TAE levels that are low
enough, then additional buffering has to be introduced at the
edges of the network to buffer out the jitter. Buffering is not
desirable, as it reduces the total available delay budget.
Timing Alignment Error:
Timing Alignment Error (TAE) is problematic to Fronthaul networks
and must be minimized. If the transport network cannot guarantee
low enough TAE then additional buffering has to be introduced at
the edges of the network to buffer out the jitter. Buffering is
not desirable as it reduces the total available delay budget.
Packet Delay Variation (PDV) requirements can be derived from TAE Packet Delay Variation (PDV) requirements can be derived from TAE
for packet based Fronthaul networks. measurements for packet-based Fronthaul networks.
* For multiple input multiple output (MIMO) or TX diversity * For MIMO or TX diversity transmissions, at each carrier
transmissions, at each carrier frequency, TAE shall not exceed frequency, TAE measurements shall not exceed 65 ns (i.e.,
65 ns (i.e. 1/4 Tc). 1/4 Tc).
* For intra-band contiguous carrier aggregation, with or without * For intra-band contiguous carrier aggregation, with or without
MIMO or TX diversity, TAE shall not exceed 130 ns (i.e. 1/2 MIMO or TX diversity, TAE measurements shall not exceed 130 ns
Tc). (i.e., 1/2 Tc).
* For intra-band non-contiguous carrier aggregation, with or * For intra-band non-contiguous carrier aggregation, with or
without MIMO or TX diversity, TAE shall not exceed 260 ns (i.e. without MIMO or TX diversity, TAE measurements shall not exceed
one Tc). 260 ns (i.e., 1 Tc).
* For inter-band carrier aggregation, with or without MIMO or TX * For inter-band carrier aggregation, with or without MIMO or TX
diversity, TAE shall not exceed 260 ns. diversity, TAE measurements shall not exceed 260 ns.
Transport link contribution to radio frequency error: Transport link contribution to radio frequency errors:
+-2 PPB. This value is considered to be "available" for the +-2 PPB. This value is considered to be "available" for the
Fronthaul link out of the total 50 PPB budget reserved for the Fronthaul link out of the total 50 PPB budget reserved for the
radio interface. Note: the reason that the transport link radio interface. Note that the transport link contributes to
contributes to radio frequency error is as follows. At the time radio frequency errors for the following reason: at the time of
of this writing, Fronthaul communication is from the radio unit to this writing, Fronthaul communication is direct communication from
remote radio head directly. The remote radio head is essentially the radio unit to the RRH. The RRH is essentially a passive
a passive device (without buffering etc.) The transport drives device (e.g., without buffering). The transport drives the
the antenna directly by feeding it with samples and everything the antenna directly by feeding it with samples, and everything the
transport adds will be introduced to radio as-is. So if the transport adds will be introduced to the radio "as is". So, if
transport causes additional frequency error that shows immediately the transport causes any additional frequency errors, the errors
on the radio as well. Note: performance guarantees of low will show up immediately on the radio as well. Note that
nanosecond values such as these are considered to be below the performance guarantees of low-nanosecond values such as these are
DetNet layer - it is assumed that the underlying implementation, considered to be below the DetNet layer -- it is assumed that the
e.g. the hardware, will provide sufficient support to enable this underlying implementation (e.g., the hardware) will provide
level of performance. These values are maintained in the use case sufficient support to enable this level of performance. These
to give an indication of the overall application. values are maintained in the use case to give an indication of the
overall application.
The above listed time synchronization requirements are difficult to The above-listed time-synchronization requirements are difficult to
meet with point-to-point connected networks, and more difficult when meet with point-to-point connected networks and are more difficult to
the network includes multiple hops. It is expected that networks meet when the network includes multiple hops. It is expected that
must include buffering at the ends of the connections as imposed by networks must include buffering at the ends of the connections as
the jitter requirements, since trying to meet the jitter requirements imposed by the jitter requirements, since trying to meet the jitter
in every intermediate node is likely to be too costly. However, requirements in every intermediate node is likely to be too costly.
every measure to reduce jitter and delay on the path makes it easier However, every measure to reduce jitter and delay on the path makes
to meet the end-to-end requirements. it easier to meet the end-to-end requirements.
In order to meet the timing requirements both senders and receivers In order to meet the timing requirements, both senders and receivers
must remain time synchronized, demanding very accurate clock must remain time synchronized, demanding very accurate clock
distribution, for example support for IEEE 1588 transparent clocks or distribution -- for example, support for IEEE 1588 transparent clocks
boundary clocks in every intermediate node. or boundary clocks in every intermediate node.
In cellular networks from the LTE radio era onward, phase In cellular networks from the LTE radio era onward, phase
synchronization is needed in addition to frequency synchronization synchronization is needed in addition to frequency synchronization
([TS36300], [TS23401]). Time constraints are also important due to [TS36300] [TS23401]. Time constraints are also important due to
their impact on packet loss. If a packet is delivered too late, then their impact on packet loss. If a packet is delivered too late, then
the packet may be dropped by the host. the packet may be dropped by the host.
6.1.4. Transport Loss Constraints 6.1.4. Transport-Loss Constraints
Fronthaul and Midhaul networks assume almost error-free transport. Fronthaul and Midhaul networks assume that transport is almost
Errors can result in a reset of the radio interfaces, which can cause error free. Errors can cause a reset of the radio interfaces, in
reduced throughput or broken radio connectivity for mobile customers. turn causing reduced throughput or broken radio connectivity for
mobile customers.
For packetized Fronthaul and Midhaul connections packet loss may be For packetized Fronthaul and Midhaul connections, packet loss may be
caused by BER, congestion, or network failure scenarios. Different caused by BER, congestion, or network failure scenarios. Different
fronthaul functional splits are being considered by 3GPP, requiring Fronthaul "functional splits" are being considered by 3GPP, requiring
strict frame loss ratio (FLR) guarantees. As one example (referring strict Frame Loss Ratio (FLR) guarantees. As one example (referring
to the legacy CPRI split which is option 8 in 3GPP) lower layers to the legacy CPRI split, which is option 8 in 3GPP), lower-layer
splits may imply an FLR of less than 10E-7 for data traffic and less splits may imply an FLR of less than 10^-7 for data traffic and less
than 10E-6 for control and management traffic. than 10^-6 for control and management traffic.
Many of the tools available for eliminating packet loss for Fronthaul Many of the tools available for eliminating packet loss for Fronthaul
and Midhaul networks have serious challenges, for example and Midhaul networks have serious challenges; for example,
retransmitting lost packets and/or using forward error correction retransmitting lost packets or using FEC to circumvent bit errors (or
(FEC) to circumvent bit errors is practically impossible due to the both) is practically impossible, due to the additional delay
additional delay incurred. Using redundant streams for better incurred. Using redundant streams for better guarantees of delivery
guarantees for delivery is also practically impossible in many cases is also practically impossible in many cases, due to high bandwidth
due to high bandwidth requirements of Fronthaul and Midhaul networks. requirements for Fronthaul and Midhaul networks. Protection
Protection switching is also a candidate but at the time of this switching is also a candidate, but at the time of this writing,
writing, available technologies for the path switch are too slow to available technologies for the path switch are too slow to avoid a
avoid reset of mobile interfaces. reset of mobile interfaces.
Fronthaul links are assumed to be symmetric, and all Fronthaul It is assumed that Fronthaul links are symmetric. All Fronthaul
streams (i.e. those carrying radio data) have equal priority and streams (i.e., those carrying radio data) have equal priority and
cannot delay or pre-empt each other. This implies that the network cannot delay or preempt each other.
must guarantee that each time-sensitive flow meets their schedule.
6.1.5. Security Considerations All of this implies that it is up to the network to guarantee that
each time-sensitive flow meets its schedule.
6.1.5. Cellular Radio Network Security Considerations
Establishing time-sensitive streams in the network entails reserving Establishing time-sensitive streams in the network entails reserving
networking resources for long periods of time. It is important that networking resources for long periods of time. It is important that
these reservation requests be authenticated to prevent malicious these reservation requests be authenticated to prevent malicious
reservation attempts from hostile nodes (or accidental reservation attempts from hostile nodes (or accidental
misconfiguration). This is particularly important in the case where misconfiguration). This is particularly important in the case where
the reservation requests span administrative domains. Furthermore, the reservation requests span administrative domains. Furthermore,
the reservation information itself should be digitally signed to the reservation information itself should be digitally signed to
reduce the risk of a legitimate node pushing a stale or hostile reduce the risk of a legitimate node pushing a stale or hostile
configuration into another networking node. configuration into another networking node.
Note: This is considered important for the security policy of the Note: This is considered important for the security policy of the
network, but does not affect the core DetNet architecture and design. network but does not affect the core DetNet architecture and design.
6.2. Cellular Radio Networks Today 6.2. Cellular Radio Networks Today
6.2.1. Fronthaul 6.2.1. Fronthaul
Today's Fronthaul networks typically consist of: Today's Fronthaul networks typically consist of:
o Dedicated point-to-point fiber connection is common o Dedicated point-to-point fiber connection (common)
o Proprietary protocols and framings o Proprietary protocols and framings
o Custom equipment and no real networking o Custom equipment and no real networking
At the time of this writing, solutions for Fronthaul are direct At the time of this writing, solutions for Fronthaul are direct
optical cables or Wavelength-Division Multiplexing (WDM) connections. optical cables or Wavelength-Division Multiplexing (WDM) connections.
6.2.2. Midhaul and Backhaul 6.2.2. Midhaul and Backhaul
Today's Midhaul and Backhaul networks typically consist of: Today's Midhaul and Backhaul networks typically consist of:
o Mostly normal IP networks, MPLS-TP, etc. o Mostly normal IP networks, MPLS-TP, etc.
o Clock distribution and sync using 1588 and SyncE o Clock distribution and synchronization using IEEE 1588 and syncE
Telecommunication networks in the Mid- and Backhaul are already Telecommunications networks in the Midhaul and Backhaul are already
heading towards transport networks where precise time synchronization heading towards transport networks where precise time-synchronization
support is one of the basic building blocks. While the transport support is one of the basic building blocks. In order to meet
networks themselves have practically transitioned to all-IP packet- bandwidth and cost requirements, most transport networks have already
based networks to meet the bandwidth and cost requirements, highly transitioned to all-IP packet-based networks; however, highly
accurate clock distribution has become a challenge. accurate clock distribution has become a challenge.
In the past, Mid- and Backhaul connections were typically based on In the past, Midhaul and Backhaul connections were typically based on
Time Division Multiplexing (TDM-based) and provided frequency TDM and provided frequency-synchronization capabilities as a part of
synchronization capabilities as a part of the transport media. the transport media. More recently, other technologies such as GPS
Alternatively other technologies such as Global Positioning System or syncE [syncE] have been used.
(GPS) or Synchronous Ethernet (SyncE) are used [SyncE].
Both Ethernet and IP/MPLS [RFC3031] (and PseudoWires (PWE) [RFC3985] Ethernet, IP/MPLS [RFC3031], and pseudowires (as described in
for legacy transport support) have become popular tools to build and [RFC3985] ("Pseudo Wire Emulation Edge-to-Edge (PWE3) Architecture")
manage new all-IP Radio Access Networks (RANs) for legacy transport support)) have become popular tools for building
[I-D.kh-spring-ip-ran-use-case]. Although various timing and and managing new all-IP Radio Access Networks (RANs)
synchronization optimizations have already been proposed and [SR-IP-RAN-Use-Case]. Although various timing and synchronization
implemented including 1588 PTP enhancements optimizations have already been proposed and implemented, including
[I-D.ietf-tictoc-1588overmpls] and [RFC8169], these solution are not PTP enhancements [IEEE-1588] (see also [Timing-over-MPLS] and
necessarily sufficient for the forthcoming RAN architectures nor do [RFC8169]), these solutions are not necessarily sufficient for the
they guarantee the more stringent time-synchronization requirements forthcoming RAN architectures, nor do they guarantee the more
such as [CPRI]. stringent time-synchronization requirements such as [CPRI].
There are also existing solutions for TDM over IP such as [RFC4553], Existing solutions for TDM over IP include those discussed in
[RFC5086], and [RFC5087], as well as TDM over Ethernet transports [RFC4553], [RFC5086], and [RFC5087]; [MEF8] addresses TDM over
such as [MEF8]. Ethernet transports.
6.3. Cellular Radio Networks Future 6.3. Cellular Radio Networks in the Future
Future Cellular Radio Networks will be based on a mix of different Future cellular radio networks will be based on a mix of different
xHaul networks (xHaul = front-, mid- and backhaul), and future xHaul networks (xHaul = Fronthaul, Midhaul, and Backhaul), and future
transport networks should be able to support all of them transport networks should be able to support all of them
simultaneously. It is already envisioned today that: simultaneously. It is already envisioned today that:
o Not all "cellular radio network" traffic will be IP, for example o Not all "cellular radio network" traffic will be IP; for example,
some will remain at Layer 2 (e.g. Ethernet based). DetNet some will remain at Layer 2 (e.g., Ethernet based). DetNet
solutions must address all traffic types (Layer 2, Layer 3) with solutions must address all traffic types (Layer 2 and Layer 3)
the same tools and allow their transport simultaneously. with the same tools and allow their transport simultaneously.
o All forms of xHaul networks will need some form of DetNet o All types of xHaul networks will need some types of DetNet
solutions. For example with the advent of 5G some Backhaul solutions. For example, with the advent of 5G, some Backhaul
traffic will also have DetNet requirements, for example traffic traffic will also have DetNet requirements (for example, traffic
belonging to time-critical 5G applications. belonging to time-critical 5G applications).
o Different splits of the functionality run on the base stations and o Different functional splits between the base stations and the
the on-site units could co-exist on the same Fronthaul and on-site units could coexist on the same Fronthaul and Backhaul
Backhaul network. network.
Future Cellular Radio networks should contain the following: Future cellular radio networks should contain the following:
o Unified standards-based transport protocols and standard o Unified standards-based transport protocols and standard
networking equipment that can make use of underlying deterministic networking equipment that can make use of underlying deterministic
link-layer services link-layer services
o Unified and standards-based network management systems and o Unified and standards-based network management systems and
protocols in all parts of the network (including Fronthaul) protocols in all parts of the network (including Fronthaul)
New radio access network deployment models and architectures may New RAN deployment models and architectures may require TSN services
require time- sensitive networking services with strict requirements with strict requirements on other parts of the network that
on other parts of the network that previously were not considered to previously were not considered to be packetized at all. Time and
be packetized at all. Time and synchronization support are already synchronization support are already topical for Backhaul and Midhaul
topical for Backhaul and Midhaul packet networks [MEF22.1.1] and are packet networks [MEF22.1.1] and are also becoming a real issue for
becoming a real issue for Fronthaul networks also. Specifically in Fronthaul networks. Specifically, in Fronthaul networks, the timing
Fronthaul networks the timing and synchronization requirements can be and synchronization requirements can be extreme for packet-based
extreme for packet based technologies, for example, on the order of technologies -- for example, on the order of a PDV of +-20 ns or less
sub +-20 ns packet delay variation (PDV) and frequency accuracy of and frequency accuracy of +-0.002 PPM [Fronthaul].
+0.002 PPM [Fronthaul].
The actual transport protocols and/or solutions to establish required The actual transport protocols and/or solutions for establishing
transport "circuits" (pinned-down paths) for Fronthaul traffic are required transport "circuits" (pinned-down paths) for Fronthaul
still undefined. Those are likely to include (but are not limited traffic are still undefined. Those protocols are likely to include
to) solutions directly over Ethernet, over IP, and using MPLS/ (but are not limited to) solutions directly over Ethernet, over IP,
PseudoWire transport. and using MPLS/pseudowire transport.
Interesting and important work for time-sensitive networking has been Interesting and important work for TSN has been done for Ethernet
done for Ethernet [TSNTG], which specifies the use of IEEE 1588 time [IEEE-8021TSNTG]; this work specifies the use of PTP [IEEE-1588] in
precision protocol (PTP) [IEEE1588] in the context of IEEE 802.1D and the context of IEEE 802.1D and IEEE 802.1Q. [IEEE-8021AS] specifies
IEEE 802.1Q. [IEEE8021AS] specifies a Layer 2 time synchronizing a Layer 2 time-synchronizing service, and other specifications such
service, and other specifications such as IEEE 1722 [IEEE1722] as IEEE 1722 [IEEE-1722] specify Ethernet-based Layer 2 transport for
specify Ethernet-based Layer-2 transport for time-sensitive streams. time-sensitive streams.
However even these Ethernet TSN features may not be sufficient for However, even these Ethernet TSN features may not be sufficient for
Fronthaul traffic. Therefore, having specific profiles that take the Fronthaul traffic. Therefore, having specific profiles that take
requirements of Fronthaul into account is desirable [IEEE8021CM]. Fronthaul requirements into account is desirable [IEEE-8021CM].
New promising work seeks to enable the transport of time-sensitive New promising work seeks to enable the transport of time-sensitive
fronthaul streams in Ethernet bridged networks [IEEE8021CM]. Fronthaul streams in Ethernet bridged networks [IEEE-8021CM].
Analogous to IEEE 1722 there is an ongoing standardization effort to Analogous to IEEE 1722, standardization efforts in the IEEE 1914.3
define the Layer-2 transport encapsulation format for transporting Task Force [IEEE-19143] to define the Layer 2 transport encapsulation
radio over Ethernet (RoE) in the IEEE 1904.3 Task Force [IEEE19143]. format for transporting Radio over Ethernet (RoE) are ongoing.
As mentioned in Section 6.1.2, 5G communications will provide one of As mentioned in Section 6.1.2, 5G communications will provide one of
the most challenging cases for delay sensitive networking. In order the most challenging cases for delay-sensitive networking. In order
to meet the challenges of ultra-low latency and ultra-high to meet the challenges of ultra-low latency and ultra-high
throughput, 3GPP has studied various "functional splits" for 5G, throughput, 3GPP has studied various functional splits for 5G, i.e.,
i.e., physical decomposition of the gNodeB base station and physical decomposition of the 5G "gNodeB" base station and deployment
deployment of its functional blocks in different locations [TR38801]. of its functional blocks in different locations [TR38801].
These splits are numbered from split option 1 (Dual Connectivity, a These splits are numbered from split option 1 (dual connectivity, a
split in which the radio resource control is centralized and other split in which the radio resource control is centralized and other
radio stack layers are in distributed units) to split option 8 (a radio stack layers are in distributed units) to split option 8 (a
PHY-RF split in which RF functionality is in a distributed unit and PHY-RF split in which RF functionality is in a distributed unit and
the rest of the radio stack is in the centralized unit), with each the rest of the radio stack is in the centralized unit), with each
intermediate split having its own data rate and delay requirements. intermediate split having its own data-rate and delay requirements.
Packetized versions of different splits have been proposed including Packetized versions of different splits have been proposed, including
eCPRI [eCPRI] and RoE (as previously noted). Both provide Ethernet enhanced CPRI (eCPRI) [eCPRI] and RoE (as previously noted). Both
encapsulations, and eCPRI is also capable of IP encapsulation. provide Ethernet encapsulations, and eCPRI is also capable of IP
encapsulation.
All-IP RANs and xHaul networks would benefit from time All-IP RANs and xHaul networks would benefit from time
synchronization and time-sensitive transport services. Although synchronization and time-sensitive transport services. Although
Ethernet appears to be the unifying technology for the transport, Ethernet appears to be the unifying technology for the transport,
there is still a disconnect providing Layer 3 services. The protocol there is still a disconnect when it comes to providing Layer 3
stack typically has a number of layers below the Ethernet Layer 2 services. The protocol stack typically has a number of layers below
that shows up to the Layer 3 IP transport. It is not uncommon that Ethernet Layer 2 that might be "visible" to Layer 3. In a fairly
on top of the lowest layer (optical) transport there is the first common scenario, on top of the lowest-layer (optical) transport is
layer of Ethernet followed one or more layers of MPLS, PseudoWires the first (lowest) Ethernet layer, then one or more layers of MPLS,
and/or other tunneling protocols finally carrying the Ethernet layer pseudowires, and/or other tunneling protocols, and finally one or
visible to the user plane IP traffic. more Ethernet layers that are visible to Layer 3.
While there are existing technologies to establish circuits through
the routed and switched networks (especially in MPLS/PWE space),
there is still no way to signal the time synchronization and time-
sensitive stream requirements/reservations for Layer-3 flows in a way
that addresses the entire transport stack, including the Ethernet
layers that need to be configured.
Furthermore, not all "user plane" traffic will be IP. Therefore, the Although there exist technologies for establishing circuits through
same solution also must address the use cases where the user plane the routed and switched networks (especially in the MPLS/PWE space),
traffic is a different layer, for example Ethernet frames. there is still no way to signal the time-synchronization and
time-sensitive stream requirements/reservations for Layer 3 flows in
a way that addresses the entire transport stack, including the
Ethernet layers that need to be configured.
There is existing work describing the problem statement Furthermore, not all "user-plane" traffic will be IP. Therefore, the
[I-D.ietf-detnet-problem-statement] and the architecture solution in question also must address the use cases where the
[I-D.ietf-detnet-architecture] for deterministic networking (DetNet) user-plane traffic is on a different layer (for example, Ethernet
that targets solutions for time-sensitive (IP/transport) streams with frames).
deterministic properties over Ethernet-based switched networks.
6.4. Cellular Radio Networks Asks 6.4. Cellular Radio Networks Requests to the IETF
A standard for data plane transport specification which is: A standard for data-plane transport specifications that is:
o Unified among all xHauls (meaning that different flows with o Unified among all xHauls (meaning that different flows with
diverse DetNet requirements can coexist in the same network and diverse DetNet requirements can coexist in the same network and
traverse the same nodes without interfering with each other) traverse the same nodes without interfering with each other)
o Deployed in a highly deterministic network environment o Deployed in a highly deterministic network environment
o Capable of supporting multiple functional splits simultaneously, o Capable of supporting multiple functional splits simultaneously,
including existing Backhaul and CPRI Fronthaul and potentially new including existing Backhaul and CPRI Fronthaul, and (potentially)
modes as defined for example in 3GPP; these goals can be supported new modes as defined, for example, in 3GPP; these goals can be
by the existing DetNet Use Case Common Themes, notably "Mix of supported by the existing DetNet use case "common themes"
Deterministic and Best-Effort Traffic", "Bounded Latency", "Low (Section 11); of special note are Sections 11.1.8 ("Mix of
Latency", "Symmetrical Path Delays", and "Deterministic Flows". Deterministic and Best-Effort Traffic"), 11.3.1 ("Bounded
Latency"), 11.3.2 ("Low Latency"), 11.3.4 ("Symmetrical Path
Delays"), and 11.6 ("Deterministic Flows")
o Capable of supporting Network Slicing and Multi-tenancy; these o Capable of supporting network slicing and multi-tenancy; these
goals can be supported by the same DetNet themes noted above. goals can be supported by the same DetNet themes noted above
o Capable of transporting both in-band and out-band control traffic o Capable of transporting both in-band and out-of-band control
(OAM info, ...). traffic (e.g., Operations, Administration, and Maintenance (OAM)
information)
o Deployable over multiple data link technologies (e.g., IEEE 802.3, o Deployable over multiple data-link technologies (e.g., IEEE 802.3,
mmWave, etc.). mmWave)
A standard for data flow information models that are: A standard for data-flow information models that is:
o Aware of the time sensitivity and constraints of the target o Aware of the time sensitivity and constraints of the target
networking environment networking environment
o Aware of underlying deterministic networking services (e.g., on o Aware of underlying deterministic networking services (e.g., on
the Ethernet layer) the Ethernet layer)
7. Industrial Machine to Machine (M2M) 7. Industrial Machine to Machine (M2M)
7.1. Use Case Description 7.1. Use Case Description
Industrial Automation in general refers to automation of "Industrial automation" in general refers to automation of
manufacturing, quality control and material processing. This manufacturing, quality control, and material processing. This M2M
"machine to machine" (M2M) use case considers machine units in a use case focuses on machine units on a plant floor that periodically
plant floor which periodically exchange data with upstream or exchange data with upstream or downstream machine modules and/or a
downstream machine modules and/or a supervisory controller within a supervisory controller within a LAN.
local area network.
The actors of M2M communication are Programmable Logic Controllers PLCs are the "actors" in M2M communications. Communication between
(PLCs). Communication between PLCs and between PLCs and the PLCs, and between PLCs and the supervisory PLC (S-PLC), is achieved
supervisory PLC (S-PLC) is achieved via critical control/data streams via critical control/data streams (Figure 11).
Figure 11.
S (Sensor) S (Sensor)
\ +-----+ \ +-----+
PLC__ \.--. .--. ---| MES | PLC__ \.--. .--. ---| MES |
\_( `. _( `./ +-----+ \_( `. _( `./ +-----+
A------( Local )-------------( L2 ) A------( Local )-------------( L2 )
( Net ) ( Net ) +-------+ ( Net ) ( Net ) +-------+
/`--(___.-' `--(___.-' ----| S-PLC | /`--(___.-' `--(___.-' ----| S-PLC |
S_/ / PLC .--. / +-------+ S_/ / PLC .--. / +-------+
A_/ \_( `. A_/ \_( `.
(Actuator) ( Local ) (Actuator) ( Local )
( Net ) ( Net )
/`--(___.-'\ /`--(___.-'\
/ \ A / \ A
S A S A
Figure 11: Current Generic Industrial M2M Network Architecture Figure 11: Current Generic Industrial M2M Network Architecture
This use case focuses on PLC-related communications; communication to This use case focuses on PLC-related communications; communication to
Manufacturing-Execution-Systems (MESs) are not addressed. Manufacturing Execution Systems (MESs) are not addressed.
This use case covers only critical control/data streams; non-critical This use case covers only critical control/data streams; non-critical
traffic between industrial automation applications (such as traffic between industrial automation applications (such as
communication of state, configuration, set-up, and database communication of state, configuration, setup, and database
communication) are adequately served by prioritizing techniques communication) is adequately served by prioritizing techniques
available at the time of this writing. Such traffic can use up to available at the time of this writing. Such traffic can use up to
80% of the total bandwidth required. There is also a subset of non- 80% of the total bandwidth required. There is also a subset of
time-critical traffic that must be reliable even though it is not non-time-critical traffic that must be reliable even though it is not
time-sensitive. time sensitive.
In this use case the primary need for deterministic networking is to In this use case, deterministic networking is primarily needed to
provide end-to-end delivery of M2M messages within specific timing provide end-to-end delivery of M2M messages within specific timing
constraints, for example in closed loop automation control. Today constraints -- for example, in closed-loop automation control.
this level of determinism is provided by proprietary networking Today, this level of determinism is provided by proprietary
technologies. In addition, standard networking technologies are used networking technologies. In addition, standard networking
to connect the local network to remote industrial automation sites, technologies are used to connect the local network to remote
e.g. over an enterprise or metro network which also carries other industrial automation sites, e.g., over an enterprise or metro
types of traffic. Therefore, flows that should be forwarded with network that also carries other types of traffic. Therefore, flows
deterministic guarantees need to be sustained regardless of the that should be forwarded with deterministic guarantees need to be
amount of other flows in those networks. sustained, regardless of the amount of other flows in those networks.
7.2. Industrial M2M Communication Today 7.2. Industrial M2M Communications Today
Today, proprietary networks fulfill the needed timing and Today, proprietary networks fulfill the needed timing and
availability for M2M networks. availability for M2M networks.
The network topologies used today by industrial automation are The network topologies used today by industrial automation are
similar to those used by telecom networks: Daisy Chain, Ring, Hub and similar to those used by telecom networks: daisy chain, ring,
Spoke, and Comb (a subset of Daisy Chain). hub-and-spoke, and "comb" (a subset of daisy chain).
PLC-related control/data streams are transmitted periodically and PLC-related control/data streams are transmitted periodically and
carry either a pre-configured payload or a payload configured during carry either a preconfigured payload or a payload configured during
runtime. runtime.
Some industrial applications require time synchronization at the end Some industrial applications require time synchronization at the end
nodes. For such time-coordinated PLCs, accuracy of 1 microsecond is nodes. For such time-coordinated PLCs, accuracy of 1 us is required.
required. Even in the case of "non-time-coordinated" PLCs time sync Even in the case of "non-time-coordinated" PLCs, time synchronization
may be needed e.g. for timestamping of sensor data. may be needed, e.g., for timestamping of sensor data.
Industrial network scenarios require advanced security solutions. At Industrial-network scenarios require advanced security solutions. At
the time of this writing, many industrial production networks are the time of this writing, many industrial production networks are
physically separated. Preventing critical flows from being leaked physically separated. Filtering policies that are typically enforced
outside a domain is handled by filtering policies that are typically in firewalls are used to prevent critical flows from being leaked
enforced in firewalls. outside a domain.
7.2.1. Transport Parameters 7.2.1. Transport Parameters
The Cycle Time defines the frequency of message(s) between industrial The cycle time defines the frequency of message(s) between industrial
actors. The Cycle Time is application dependent, in the range of 1ms actors. The cycle time is application dependent, in the range of
- 100ms for critical control/data streams. 1-100 ms for critical control/data streams.
Because industrial applications assume deterministic transport for Because industrial applications assume that deterministic transport
critical Control-Data-Stream parameters (instead of defining latency will be used for critical control-data-stream parameters (instead of
and delay variation parameters) it is sufficient to fulfill the upper having to define latency and delay-variation parameters), it is
bound of latency (maximum latency). The underlying networking sufficient to fulfill requirements regarding the upper bound of
infrastructure must ensure a maximum end-to-end delivery time of latency (maximum latency). The underlying networking infrastructure
messages in the range of 100 microseconds to 50 milliseconds must ensure a maximum end-to-end message delivery time in the range
depending on the control loop application. of 100 us to 50 ms, depending on the control-loop application.
The bandwidth requirements of control/data streams are usually The bandwidth requirements of control/data streams are usually
calculated directly from the bytes-per-cycle parameter of the control calculated directly from the bytes-per-cycle parameter of the control
loop. For PLC-to-PLC communication one can expect 2 - 32 streams loop. For PLC-to-PLC communication, one can expect 2-32 streams with
with packet size in the range of 100 - 700 bytes. For S-PLC to PLCs packet sizes in the range of 100-700 bytes. For S-PLC-to-PLC
the number of streams is higher - up to 256 streams. Usually no more communication, the number of streams is higher -- up to 256 streams.
than 20% of available bandwidth is used for critical control/data Usually, no more than 20% of available bandwidth is used for
streams. In today's networks 1Gbps links are commonly used. critical control/data streams. In today's networks, 1 Gbps links
are commonly used.
Most PLC control loops are rather tolerant of packet loss, however Most PLC control loops are rather tolerant of packet loss; however,
critical control/data streams accept no more than 1 packet loss per critical control/data streams accept a loss of no more than one
consecutive communication cycle (i.e. if a packet gets lost in cycle packet per consecutive communication cycle (i.e., if a packet gets
"n", then the next cycle ("n+1") must be lossless). After two or lost in cycle "n", then the next cycle ("n+1") must be lossless).
more consecutive packet losses the network may be considered to be After the loss of two or more consecutive packets, the network may be
"down" by the Application. considered to be "down" by the application.
As network downtime may impact the whole production system the As network downtime may impact the whole production system, the
required network availability is rather high (99.999%). required network availability is rather high (99.999%).
Based on the above parameters some form of redundancy will be Based on the above parameters, some form of redundancy will be
required for M2M communications, however any individual solution required for M2M communications; however, any individual solution
depends on several parameters including cycle time, delivery time, depends on several parameters, including cycle time and
etc. delivery time.
7.2.2. Stream Creation and Destruction 7.2.2. Stream Creation and Destruction
In an industrial environment, critical control/data streams are In an industrial environment, critical control/data streams are
created rather infrequently, on the order of ~10 times per day / week created rather infrequently, on the order of ~10 times per
/ month. Most of these critical control/data streams get created at day/week/month. Most of these critical control/data streams get
machine startup, however flexibility is also needed during runtime, created at machine startup; however, flexibility is also needed
for example when adding or removing a machine. Going forward as during runtime -- for example, when adding or removing a machine. As
production systems become more flexible, there will be a significant production systems become more flexible going forward, there will be
increase in the rate at which streams are created, changed and a significant increase in the rate at which streams are created,
destroyed. changed, and destroyed.
7.3. Industrial M2M Future 7.3. Industrial M2M in the Future
We foresee a converged IP-standards-based network with deterministic We foresee a converged IP-standards-based network with deterministic
properties that can satisfy the timing, security and reliability properties that can satisfy the timing, security, and reliability
constraints described above. Today's proprietary networks could then constraints described above. Today's proprietary networks could then
be interfaced to such a network via gateways or, in the case of new be interfaced to such a network via gateways; alternatively, in the
installations, devices could be connected directly to the converged case of new installations, devices could be connected directly to the
network. converged network.
For this use case time synchronization accuracy on the order of 1us For this use case, time-synchronization accuracy on the order of 1 us
is expected. is expected.
7.4. Industrial M2M Asks 7.4. Industrial M2M Requests to the IETF
o Converged IP-based network o Converged IP-based network
o Deterministic behavior (bounded latency and jitter ) o Deterministic behavior (bounded latency and jitter)
o High availability (presumably through redundancy) (99.999 %)
o Low message delivery time (100us - 50ms) o High availability (presumably through redundancy) (99.999%)
o Low packet loss (with bounded number of consecutive lost packets) o Low message delivery time (100 us to 50 ms)
o Low packet loss (with a bounded number of consecutive lost
packets)
o Security (e.g. prevent critical flows from being leaked between o Security (e.g., preventing critical flows from being leaked
physically separated networks) between physically separated networks)
8. Mining Industry 8. Mining Industry
8.1. Use Case Description 8.1. Use Case Description
The mining industry is highly dependent on networks to monitor and The mining industry is highly dependent on networks to monitor and
control their systems both in open-pit and underground extraction, control their systems, in both open-pit and underground extraction as
transport and refining processes. In order to reduce risks and well as in transport and refining processes. In order to reduce
increase operational efficiency in mining operations, a number of risks and increase operational efficiency in mining operations, the
processes have migrated the operators from the extraction site to location of operators has been relocated (as much as possible) from
remote control and monitoring. the extraction site to remote control and monitoring sites.
In the case of open pit mining, autonomous trucks are used to In the case of open-pit mining, autonomous trucks are used to
transport the raw materials from the open pit to the refining factory transport the raw materials from the open pit to the refining factory
where the final product (e.g. Copper) is obtained. Although the where the final product (e.g., copper) is obtained. Although the
operation is autonomous, the tracks are remotely monitored from a operation is autonomous, the tracks are remotely monitored from a
central facility. central facility.
In pit mines, the monitoring of the tailings or mine dumps is In pit mines, the monitoring of the tailings or mine dumps is
critical in order to minimize environmental pollution. In the past, critical in order to minimize environmental pollution. In the past,
monitoring has been conducted through manual inspection of pre- monitoring was conducted through manual inspection of preinstalled
installed dataloggers. Cabling is not usually exploited in such dataloggers. Cabling is not typically used in such scenarios, due to
scenarios due to the cost and complex deployment requirements. At its high cost and complex deployment requirements. At the time of
the time of this writing, wireless technologies are being employed to this writing, wireless technologies are being employed to monitor
monitor these cases permanently. Slopes are also monitored in order these cases permanently. Slopes are also monitored in order to
to anticipate possible mine collapse. Due to the unstable terrain, anticipate possible mine collapse. Due to the unstable terrain,
cable maintenance is costly and complex and hence wireless cable maintenance is costly and complex; hence, wireless technologies
technologies are employed. are employed.
In the underground monitoring case, autonomous vehicles with In the case of underground monitoring, autonomous vehicles with
extraction tools travel autonomously through the tunnels, but their extraction tools travel independently through the tunnels, but their
operational tasks (such as excavation, stone breaking and transport) operational tasks (such as excavation, stone-breaking, and transport)
are controlled remotely from a central facility. This generates are controlled remotely from a central facility. This generates
video and feedback upstream traffic plus downstream actuator control upstream video and feedback traffic plus downstream actuator-control
traffic. traffic.
8.2. Mining Industry Today 8.2. Mining Industry Today
At the time of this writing, the mining industry uses a packet At the time of this writing, the mining industry uses a
switched architecture supported by high speed ethernet. However in packet-switched architecture supported by high-speed Ethernet.
order to achieve the delay and packet loss requirements the network However, in order to comply with requirements regarding delay and
bandwidth is overestimated, thus providing very low efficiency in packet loss, the network bandwidth is overestimated. This results in
terms of resource usage. very low efficiency in terms of resource usage.
QoS is implemented at the Routers to separate video, management, QoS is implemented at the routers to separate video, management,
monitoring and process control traffic for each stream. monitoring, and process-control traffic for each stream.
Since mobility is involved in this process, the connection between Since mobility is involved in this process, the connections between
the backbone and the mobile devices (e.g. trucks, trains and the backbone and the mobile devices (e.g., trucks, trains, and
excavators) is solved using a wireless link. These links are based excavators) are implemented using a wireless link. These links are
on 802.11 for open-pit mining and "leaky feeder" communications for based on IEEE 802.11 [IEEE-80211] for open-pit mining and "leaky
underground mining. (A "leaky feeder" communication system consists feeder" communications for underground mining. (A "leaky feeder"
of a coaxial cable run along tunnels which emits and receives radio communication system consists of a coaxial cable, run along tunnels,
waves, functioning as an extended antenna. The cable is "leaky" in that emits and receives radio waves, functioning as an extended
that it has gaps or slots in its outer conductor to allow the radio antenna. The cable is "leaky" in that it has gaps or slots in its
signal to leak into or out of the cable along its entire length.) outer conductor to allow the radio signal to leak into or out of the
cable along its entire length.)
Lately in pit mines the use of LPWAN technologies has been extended: Lately, in pit mines the use of Low-Power WAN (LPWAN) technologies
Tailings, slopes and mine dumps are monitored by battery-powered has been extended: tailings, slopes, and mine dumps are monitored by
dataloggers that make use of robust long range radio technologies. battery-powered dataloggers that make use of robust long-range radio
Reliability is usually ensured through retransmissions at L2. technologies. Reliability is usually ensured through retransmissions
Gateways or concentrators act as bridges forwarding the data to the at Layer 2. Gateways or concentrators act as bridges, forwarding the
backbone ethernet network. Deterministic requirements are biased data to the backbone Ethernet network. Deterministic requirements
towards reliability rather than latency as events are slowly are biased towards reliability rather than latency, as events are
triggered or can be anticipated in advance. triggered slowly or can be anticipated in advance.
At the mineral processing stage, conveyor belts and refining At the mineral-processing stage, conveyor belts and refining
processes are controlled by a SCADA system, which provides the in- processes are controlled by a SCADA system that provides an
factory delay-constrained networking requirements. in-factory delay-constrained networking environment.
At the time of this writing, voice communications are served by a At the time of this writing, voice communications are served by a
redundant trunking infrastructure, independent from data networks. redundant trunking infrastructure, independent from data networks.
8.3. Mining Industry Future 8.3. Mining Industry in the Future
Mining operations and management are converging towards a combination Mining operations and management are converging towards a combination
of autonomous operation and teleoperation of transport and extraction of autonomous operation and teleoperation of transport and extraction
machines. This means that video, audio, monitoring and process machines. This means that video, audio, monitoring, and process-
control traffic will increase dramatically. Ideally, all activities control traffic will increase dramatically. Ideally, all activities
on the mine will rely on network infrastructure. at the mine will rely on network infrastructure.
Wireless for open-pit mining is already a reality with LPWAN Wireless for open-pit mining is already a reality with LPWAN
technologies and it is expected to evolve to more advanced LPWAN technologies; it is expected to evolve to more-advanced LPWAN
technologies such as those based on LTE to increase last hop technologies, such as those based on LTE, to increase last-hop
reliability or novel LPWAN flavours with deterministic access. reliability or novel LPWAN flavors with deterministic access.
One area in which DetNet can improve this use case is in the wired One area in which DetNet can improve this use case is in the wired
networks that make up the "backbone network" of the system, which networks that make up the "backbone network" of the system. These
connect together many wireless access points (APs). The mobile networks connect many wireless Access Points (APs) together. The
machines (which are connected to the network via wireless) transition mobile machines (which are connected to the network via wireless)
from one AP to the next as they move about. A deterministic, transition from one AP to the next as they move about. A
reliable, low latency backbone can enable these transitions to be deterministic, reliable, low-latency backbone can enable these
more reliable. transitions to be more reliable.
Connections which extend all the way from the base stations to the Connections that extend all the way from the base stations to the
machinery via a mix of wired and wireless hops would also be machinery via a mix of wired and wireless hops would also be
beneficial, for example to improve remote control responsiveness of beneficial -- for example, to improve the responsiveness of digging
digging machines. However to guarantee deterministic performance of machines to remote control. However, to guarantee deterministic
a DetNet, the end-to-end underlying network must be deterministic. performance of a DetNet, the end-to-end underlying network must be
Thus for this use case if a deterministic wireless transport is deterministic. Thus, for this use case, if a deterministic wireless
integrated with a wire-based DetNet network, it could create the transport is integrated with a wire-based DetNet network, it could
desired wired plus wireless end-to-end deterministic network. create the desired wired plus wireless end-to-end deterministic
network.
8.4. Mining Industry Asks 8.4. Mining Industry Requests to the IETF
o Improved bandwidth efficiency o Improved bandwidth efficiency
o Very low delay to enable machine teleoperation o Very low delay, to enable machine teleoperation
o Dedicated bandwidth usage for high resolution video streams o Dedicated bandwidth usage for high-resolution video streams
o Predictable delay to enable realtime monitoring o Predictable delay, to enable real-time monitoring
o Potential to construct a unified DetNet network over a combination o Potential for constructing a unified DetNet network over a
of wired and deterministic wireless links combination of wired and deterministic wireless links
9. Private Blockchain 9. Private Blockchain
9.1. Use Case Description 9.1. Use Case Description
Blockchain was created with bitcoin as a 'public' blockchain on the Blockchain was created with Bitcoin as a "public" blockchain on the
open Internet, however blockchain has also spread far beyond its open Internet; however, blockchain has also spread far beyond its
original host into various industries such as smart manufacturing, original host into various industries, such as smart manufacturing,
logistics, security, legal rights and others. In these industries logistics, security, legal rights, and others. In these industries,
blockchain runs in designated and carefully managed networks in which blockchain runs in designated and carefully managed networks in which
deterministic networking requirements could be addressed by DetNet. deterministic networking requirements could be addressed by DetNet.
Such implementations are referred to as 'private' blockchain. Such implementations are referred to as "private" blockchain.
The sole distinction between public and private blockchain is defined The sole distinction between public and private blockchain is defined
by who is allowed to participate in the network, execute the by who is allowed to participate in the network, execute the
consensus protocol, and maintain the shared ledger. consensus protocol, and maintain the shared ledger.
Today's networks treat the traffic from blockchain on a best-effort Today's networks manage the traffic from blockchain on a best-effort
basis, but blockchain operation could be made much more efficient if basis, but blockchain operation could be made much more efficient if
deterministic networking services were available to minimize latency deterministic networking services were available to minimize latency
and packet loss in the network. and packet loss in the network.
9.1.1. Blockchain Operation 9.1.1. Blockchain Operation
A 'block' runs as a container of a batch of primary items such as A "block" runs as a container of a batch of primary items (e.g.,
transactions, property records etc. The blocks are chained in such a transactions, property records). The blocks are chained in such a
way that the hash of the previous block works as the pointer to the way that the hash of the previous block works as the pointer to the
header of the new block. Confirmation of each block requires a header of the new block. Confirmation of each block requires a
consensus mechanism. When an item arrives at a blockchain node, the consensus mechanism. When an item arrives at a blockchain node, the
latter broadcasts this item to the rest of the nodes which receive latter broadcasts this item to the rest of the nodes, which receive
and verify it and put it in the ongoing block. The block it, verify it, and put it in the ongoing block. The block
confirmation process begins as the number of items reaches the confirmation process begins as the number of items reaches the
predefined block capacity, at which time the node broadcasts its predefined block capacity, at which time the node broadcasts its
proved block to the rest of the nodes, to be verified and chained. proved block to the rest of the nodes, to be verified and chained.
The result is that block N+1 of each chain transitively vouches for The result is that block N+1 of each chain transitively vouches for
blocks N and before of that chain. blocks N and previous of that chain.
9.1.2. Blockchain Network Architecture 9.1.2. Blockchain Network Architecture
Blockchain node communication and coordination is achieved mainly Blockchain node communication and coordination are achieved mainly
through frequent point-to-multi-point communication, however through frequent point-to-multipoint communication; however,
persistent point-to-point connections are used to transport both the persistent point-to-point connections are used to transport both the
items and the blocks to the other nodes. For example, consider the items and the blocks to the other nodes. For example, consider the
following implementation. following implementation.
When a node is initiated, it first requests the other nodes' address When a node is initiated, it first requests the other nodes'
from a specific entity such as DNS, then it creates persistent addresses from a specific entity, such as DNS. The node then creates
connections each of with other nodes. If a node confirms an item, it persistent connections with each of the other nodes. If a node
sends the item to the other nodes via these persistent connections. confirms an item, it sends the item to the other nodes via these
persistent connections.
As a new block in a node is completed and is proven by the As a new block in a node is completed and is proven by the
surrounding nodes, it propagates towards its neighbor nodes. When surrounding nodes, it propagates towards its neighbor nodes. When
node A receives a block, it verifies it, then sends an invite message node A receives a block, it verifies it and then sends an invite
to its neighbor B. Neighbor B checks to see if the designated block message to its neighbor B. Neighbor B checks to see if the
is available, and responds to A if it is unavailable, then A sends designated block is available and responds to A if it is unavailable;
the complete block to B. B repeats the process (as done by A above) A then sends the complete block to B. B repeats the process (as was
to start the next round of block propagation. done by A) to start the next round of block propagation.
The challenge of blockchain network operation is not overall data The challenge of blockchain network operation is not overall data
rates, since the volume from both block and item stays between rates, since the volume from both the block and the item stays
hundreds of bytes to a couple of megabytes per second, but is in between hundreds of bytes and a couple of megabytes per second;
transporting the blocks with minimum latency to maximize efficiency rather, the challenge is in transporting the blocks with minimum
of the blockchain consensus process. The efficiency of differing latency to maximize the efficiency of the blockchain consensus
implementations of the consensus process may be affected to a process. The efficiency of differing implementations of the
differing degree by the latency (and variation of latency) of the consensus process may be affected to a differing degree by the
network. latency (and variation of latency) of the network.
9.1.3. Security Considerations 9.1.3. Blockchain Security Considerations
Security is crucial to blockchain applications, and at the time of Security is crucial to blockchain applications; at the time of this
this writing, blockchain systems address security issues mainly at writing, blockchain systems address security issues mainly at the
the application level, where cryptography as well as hash-based application level, where cryptography as well as hash-based consensus
consensus play a leading role in preventing both double-spending and play a leading role in preventing both double-spending and malicious
malicious service attacks. However, there is concern that in the service attacks. However, there is concern that in the proposed use
proposed use case of a private blockchain network which is dependent case for a private blockchain network that is dependent on
on deterministic properties, the network could be vulnerable to deterministic properties the network could be vulnerable to delays
delays and other specific attacks against determinism which could and other specific attacks against determinism, as these delays and
interrupt service. attacks could interrupt service.
9.2. Private Blockchain Today 9.2. Private Blockchain Today
Today private blockchain runs in L2 or L3 VPN, in general without Today, private blockchain runs in Layer 2 or Layer 3 VPNs, generally
guaranteed determinism. The industry players are starting to realize without guaranteed determinism. The industry players are starting to
that improving determinism in their blockchain networks could improve realize that improving determinism in their blockchain networks could
the performance of their service, but as of today these goals are not improve the performance of their service, but at present these goals
being met. are not being met.
9.3. Private Blockchain Future 9.3. Private Blockchain in the Future
Blockchain system performance can be greatly improved through Blockchain system performance can be greatly improved through
deterministic networking service primarily because it would deterministic networking services, primarily because low latency
accelerate the consensus process. It would be valuable to be able to would accelerate the consensus process. It would be valuable to be
design a private blockchain network with the following properties: able to design a private blockchain network with the following
properties:
o Transport of point-to-multi-point traffic in a coordinated network o Transport of point-to-multipoint traffic in a coordinated network
architecture rather than at the application layer (which typically architecture rather than at the application layer (which typically
uses point-to-point connections) uses point-to-point connections)
o Guaranteed transport latency o Guaranteed transport latency
o Reduced packet loss (to the point where packet retransmission- o Reduced packet loss (to the point where delay incurred by packet
incurred delay would be negligible.) retransmissions would be negligible)
9.4. Private Blockchain Asks 9.4. Private Blockchain Requests to the IETF
o Layer 2 and Layer 3 multicast of blockchain traffic o Layer 2 and Layer 3 multicast of blockchain traffic
o Item and block delivery with bounded, low latency and negligible o Item and block delivery with bounded, low latency and negligible
packet loss packet loss
o Coexistence in a single network of blockchain and IT traffic. o Coexistence of blockchain and IT traffic in a single network
o Ability to scale the network by distributing the centralized o Ability to scale the network by distributing the centralized
control of the network across multiple control entities. control of the network across multiple control entities
10. Network Slicing 10. Network Slicing
10.1. Use Case Description 10.1. Use Case Description
Network Slicing divides one physical network infrastructure into Network slicing divides one physical network infrastructure into
multiple logical networks. Each slice, corresponding to a logical multiple logical networks. Each slice, which corresponds to a
network, uses resources and network functions independently from each logical network, uses resources and network functions independently
other. Network Slicing provides flexibility of resource allocation from each other. Network slicing provides flexibility of resource
and service quality customization. allocation and service quality customization.
Future services will demand network performance with a wide variety Future services will demand network performance with a wide variety
of characteristics such as high data rate, low latency, low loss of characteristics such as high data rate, low latency, low loss
rate, security and many other parameters. Ideally every service rate, security, and many other parameters. Ideally, every service
would have its own physical network satisfying its particular would have its own physical network satisfying its particular
performance requirements, however that would be prohibitively performance requirements; however, that would be prohibitively
expensive. Network Slicing can provide a customized slice for a expensive. Network slicing can provide a customized slice for a
single service, and multiple slices can share the same physical single service, and multiple slices can share the same physical
network. This method can optimize the performance for the service at network. This method can optimize performance for the service at
lower cost, and the flexibility of setting up and release the slices lower cost, and the flexibility of setting up and releasing the
also allows the user to allocate the network resources dynamically. slices also allows the user to allocate network resources
dynamically.
Unlike the other use cases presented here, Network Slicing is not a Unlike the other use cases presented here, network slicing is not a
specific application that depends on specific deterministic specific application that depends on specific deterministic
properties; rather it is introduced as an area of networking to which properties; rather, it is introduced as an area of networking to
DetNet might be applicable. which DetNet might be applicable.
10.2. DetNet Applied to Network Slicing 10.2. DetNet Applied to Network Slicing
10.2.1. Resource Isolation Across Slices 10.2.1. Resource Isolation across Slices
One of the requirements discussed for Network Slicing is the "hard" One of the requirements discussed for network slicing is the "hard"
separation of various users' deterministic performance. That is, it separation of various users' deterministic performance. That is, it
should be impossible for activity, lack of activity, or changes in should be impossible for activity, lack of activity, or changes in
activity of one or more users to have any appreciable effect on the activity of one or more users to have any appreciable effect on the
deterministic performance parameters of any other slices. Typical deterministic performance parameters of any other slices. Typical
techniques used today, which share a physical network among users, do techniques used today, which share a physical network among users, do
not offer this level of isolation. DetNet can supply point-to-point not offer this level of isolation. DetNet can supply point-to-point
or point-to-multipoint paths that offer bandwidth and latency or point-to-multipoint paths that offer a user bandwidth and latency
guarantees to a user that cannot be affected by other users' data guarantees that cannot be affected by other users' data traffic.
traffic. Thus DetNet is a powerful tool when latency and reliability Thus, DetNet is a powerful tool when reliability and low latency are
are required in Network Slicing. required in network slicing.
10.2.2. Deterministic Services Within Slices 10.2.2. Deterministic Services within Slices
Slices may need to provide services with DetNet-type performance Slices may need to provide services with DetNet-type performance
guarantees, however note that a system can be implemented to provide guarantees; note, however, that a system can be implemented to
such services in more than one way. For example the slice itself provide such services in more than one way. For example, the slice
might be implemented using DetNet, and thus the slice can provide itself might be implemented using DetNet, and thus the slice can
service guarantees and isolation to its users without any particular provide service guarantees and isolation to its users without any
DetNet awareness on the part of the users' applications. particular DetNet awareness on the part of the users' applications.
Alternatively, a "non-DetNet-aware" slice may host an application Alternatively, a "non-DetNet-aware" slice may host an application
that itself implements DetNet services and thus can enjoy similar that itself implements DetNet services and thus can enjoy similar
service guarantees. service guarantees.
10.3. A Network Slicing Use Case Example - 5G Bearer Network 10.3. A Network Slicing Use Case Example - 5G Bearer Network
Network Slicing is a core feature of 5G defined in 3GPP, which is Network slicing is a core feature of 5G as defined in 3GPP. The
under development at the time of this writing [TR38501]. A network system architecture for 5G is under development at the time of this
slice in a mobile network is a complete logical network including writing [TS23501]. A network slice in a mobile network is a complete
Radio Access Network (RAN) and Core Network (CN). It provides logical network, including RANs and Core Networks (CNs). It provides
telecommunication services and network capabilities, which may vary telecommunications services and network capabilities, which may vary
from slice to slice. A 5G bearer network is a typical use case of from slice to slice. A 5G bearer network is a typical use case for
Network Slicing; for example consider three 5G service scenarios: network slicing; for example, consider three 5G service scenarios:
eMMB, URLLC, and mMTC. eMBB, URLLC, and mMTC.
o eMBB (Enhanced Mobile Broadband) focuses on services characterized o eMBB (Enhanced Mobile Broadband) focuses on services characterized
by high data rates, such as high definition videos, virtual by high data rates, such as high-definition video, Virtual Reality
reality, augmented reality, and fixed mobile convergence. (VR), augmented reality, and fixed mobile convergence.
o URLLC (Ultra-Reliable and Low Latency Communications) focuses on o URLLC (Ultra-Reliable and Low Latency Communications) focuses on
latency-sensitive services, such as self-driving vehicles, remote latency-sensitive services, such as self-driving vehicles, remote
surgery, or drone control. surgery, or drone control.
o mMTC (massive Machine Type Communications) focuses on services o mMTC (massive Machine Type Communications) focuses on services
that have high requirements for connection density, such as those that have high connection-density requirements, such as those
typical for smart city and smart agriculture use cases. typically used in smart-city and smart-agriculture scenarios.
A 5G bearer network could use DetNet to provide hard resource A 5G bearer network could use DetNet to provide hard resource
isolation across slices and within the slice. For example consider isolation across slices and within a given slice. For example,
Slice-A and Slice-B, with DetNet used to transit services URLLC-A and consider Slice-A and Slice-B, with DetNet used to transit services
URLLC-B over them. Without DetNet, URLLC-A and URLLC-B would compete URLLC-A and URLLC-B over them. Without DetNet, URLLC-A and URLLC-B
for bandwidth resource, and latency and reliability would not be would compete for bandwidth resources, and latency and reliability
guaranteed. With DetNet, URLLC-A and URLLC-B have separate bandwidth requirements would not be guaranteed. With DetNet, URLLC-A and
reservation and there is no resource conflict between them, as though URLLC-B have separate bandwidth reservations; there is no resource
they were in different logical networks. conflict between them, as though they were in different physical
networks.
10.4. Non-5G Applications of Network Slicing 10.4. Non-5G Applications of Network Slicing
Although operation of services not related to 5G is not part of the Although the operation of services not related to 5G is not part of
5G Network Slicing definition and scope, Network Slicing is likely to the 5G network slicing definition and scope, network slicing is
become a preferred approach to providing various services across a likely to become a preferred approach for providing various services
shared physical infrastructure. Examples include providing across a shared physical infrastructure. Examples include providing
electrical utilities services and pro audio services via slices. Use services for electrical utilities and pro audio via slices. Use
cases like these could become more common once the work for the 5G cases like these could become more common once the work for the 5G CN
core network evolves to include wired as well as wireless access. evolves to include wired as well as wireless access.
10.5. Limitations of DetNet in Network Slicing 10.5. Limitations of DetNet in Network Slicing
DetNet cannot cover every Network Slicing use case. One issue is DetNet cannot cover every network slicing use case. One issue is
that DetNet is a point-to-point or point-to-multipoint technology, that DetNet is a point-to-point or point-to-multipoint technology;
however Network Slicing ultimately needs multi-point to multi-point however, network slicing ultimately needs multipoint-to-multipoint
guarantees. Another issue is that the number of flows that can be guarantees. Another issue is that the number of flows that can be
carried by DetNet is limited by DetNet scalability; flow aggregation carried by DetNet is limited by DetNet scalability; flow aggregation
and queuing management modification may help address this. and queuing management modification may help address this issue.
Additional work and discussion are needed to address these topics. Additional work and discussion are needed to address these topics.
10.6. Network Slicing Today and Future 10.6. Network Slicing Today and in the Future
Network Slicing has the promise to satisfy many requirements of Network slicing has promise in terms of satisfying many requirements
future network deployment scenarios, but it is still a collection of of future network deployment scenarios, but it is still a collection
ideas and analysis, without a specific technical solution. DetNet is of ideas and analyses without a specific technical solution. DetNet
one of various technologies that have potential to be used in Network is one of various technologies that could potentially be used in
Slicing, along with for example Flex-E and Segment Routing. For more network slicing, along with, for example, Flex-E and segment routing.
information please see the IETF99 Network Slicing BOF session agenda For more information, please see the IETF 99 Network Slicing BoF
and materials. session agenda and materials as provided in [IETF99-netslicing-BoF].
10.7. Network Slicing Asks 10.7. Network Slicing Requests to the IETF
o Isolation from other flows through Queuing Management o Isolation from other flows through queuing management
o Service Quality Customization and Guarantee o Service quality customization and guarantees
o Security o Security
11. Use Case Common Themes 11. Use Case Common Themes
This section summarizes the expected properties of a DetNet network, This section summarizes the expected properties of a DetNet network,
based on the use cases as described in this draft. based on the use cases as described in this document.
11.1. Unified, standards-based network 11.1. Unified, Standards-Based Networks
11.1.1. Extensions to Ethernet 11.1.1. Extensions to Ethernet
A DetNet network is not "a new kind of network" - it based on A DetNet network is not "a new kind of network" -- it is based on
extensions to existing Ethernet standards, including elements of IEEE extensions to existing Ethernet standards, including elements of
802.1 AVB/TSN and related standards. Presumably it will be possible IEEE 802.1 TSN and related standards. Presumably, it will be
to run DetNet over other underlying transports besides Ethernet, but possible to run DetNet over other underlying transports besides
Ethernet is explicitly supported. Ethernet, but Ethernet is explicitly supported.
11.1.2. Centrally Administered 11.1.2. Centrally Administered Networks
In general a DetNet network is not expected to be "plug and play" - In general, a DetNet network is not expected to be "plug and play";
it is expected that there is some centralized network configuration rather, some type of centralized network configuration and control
and control system. Such a system may be in a single central system is expected. Such a system may be in a single central
location, or it maybe distributed across multiple control entities location, or it may be distributed across multiple control entities
that function together as a unified control system for the network. that function together as a unified control system for the network.
However, the ability to "hot swap" components (e.g. due to However, the ability to "hot swap" components (e.g., due to
malfunction) is similar enough to "plug and play" that this kind of malfunction) is similar enough to "plug and play" that this kind of
behavior may be expected in DetNet networks, depending on the behavior may be expected in DetNet networks, depending on the
implementation. implementation.
11.1.3. Standardized Data Flow Information Models 11.1.3. Standardized Data-Flow Information Models
Data Flow Information Models to be used with DetNet networks are to Data-flow information models to be used with DetNet networks are to
be specified by DetNet. be specified by DetNet.
11.1.4. L2 and L3 Integration 11.1.4. Layer 2 and Layer 3 Integration
A DetNet network is intended to integrate between Layer 2 (bridged) A DetNet network is intended to integrate between Layer 2 (bridged)
network(s) (e.g. AVB/TSN LAN) and Layer 3 (routed) network(s) (e.g. network(s) (e.g., an AVB/TSN LAN) and Layer 3 (routed) network(s)
using IP-based protocols). One example of this is "making AVB/TSN- (e.g., using IP-based protocols). One example of this is making
type deterministic performance available from Layer 3 applications, AVB/TSN-type deterministic performance available from Layer 3
e.g. using RTP". Another example is "connecting two AVB/TSN LANs applications, e.g., using RTP. Another example is connecting two
("islands") together through a standard router". AVB/TSN LANs ("islands") together through a standard router.
11.1.5. Consideration for IPv4 11.1.5. IPv4 Considerations
This Use Cases draft explicitly does not specify any particular This document explicitly does not specify any particular
implementation or protocol, however it has been observed that various implementation or protocol; however, it has been observed that
of the use cases described (and their associated industries) are various use cases (and their associated industries) described herein
explicitly based on IPv4 (as opposed to IPv6) and it is not are explicitly based on IPv4 (as opposed to IPv6), and it is not
considered practical to expect them to migrate to IPv6 in order to considered practical to expect such implementations to migrate to
use DetNet. Thus the expectation is that even if not every feature IPv6 in order to use DetNet. Thus, the expectation is that even if
of DetNet is available in an IPv4 context, at least some of the not every feature of DetNet is available in an IPv4 context, at least
significant benefits (such as guaranteed end-to-end delivery and low some of the significant benefits (such as guaranteed end-to-end
latency) are expected to be available. delivery and low latency) will be available.
11.1.6. Guaranteed End-to-End Delivery 11.1.6. Guaranteed End-to-End Delivery
Packets in a DetNet flow are guaranteed not to be dropped by the Packets in a DetNet flow are guaranteed not to be dropped by the
network due to congestion. However, the network may drop packets for network due to congestion. However, the network may drop packets for
intended reasons, e.g. per security measures. Similarly best-effort intended reasons, e.g., per security measures. Similarly,
traffic on a DetNet is subject to being dropped (as on a non-DetNet best-effort traffic on a DetNet is subject to being dropped (as on a
IP network). Also note that this guarantee applies to the actions of non-DetNet IP network). Also note that this guarantee applies to
DetNet protocol software, and does not provide any guarantee against actions taken by DetNet protocol software and does not provide any
lower level errors such as media errors or checksum errors. guarantee against lower-level errors such as media errors or checksum
errors.
11.1.7. Replacement for Multiple Proprietary Deterministic Networks 11.1.7. Replacement for Multiple Proprietary Deterministic Networks
There are many proprietary non-interoperable deterministic Ethernet- There are many proprietary non-interoperable deterministic Ethernet-
based networks available; DetNet is intended to provide an open- based networks available; DetNet is intended to provide an
standards-based alternative to such networks. open-standards-based alternative to such networks.
11.1.8. Mix of Deterministic and Best-Effort Traffic 11.1.8. Mix of Deterministic and Best-Effort Traffic
DetNet is intended to support coexistance of time-sensitive DetNet is intended to support the coexistence of time-sensitive
operational (OT) traffic and information (IT) traffic on the same operational (OT) traffic and informational (IT) traffic on the same
("unified") network. ("unified") network.
11.1.9. Unused Reserved BW to be Available to Best-Effort Traffic 11.1.9. Unused Reserved Bandwidth to Be Available to Best-Effort
Traffic
If bandwidth reservations are made for a stream but the associated If bandwidth reservations are made for a stream but the associated
bandwidth is not used at any point in time, that bandwidth is made bandwidth is not used at any point in time, that bandwidth is made
available on the network for best-effort traffic. If the owner of available on the network for best-effort traffic. If the owner of
the reserved stream then starts transmitting again, the bandwidth is the reserved stream then starts transmitting again, the bandwidth is
no longer available for best-effort traffic, on a moment-to-moment no longer available for best-effort traffic; this occurs on a
basis. Note that such "temporarily available" bandwidth is not moment-to-moment basis. Note that such "temporarily available"
available for time-sensitive traffic, which must have its own bandwidth is not available for time-sensitive traffic, which must
reservation. have its own reservation.
11.1.10. Lower Cost, Multi-Vendor Solutions 11.1.10. Lower-Cost, Multi-Vendor Solutions
The DetNet network specifications are intended to enable an ecosystem The DetNet network specifications are intended to enable an ecosystem
in which multiple vendors can create interoperable products, thus in which multiple vendors can create interoperable products, thus
promoting device diversity and potentially higher numbers of each promoting device diversity and potentially higher numbers of each
device manufactured, promoting cost reduction and cost competition device manufactured, promoting cost reduction and cost competition
among vendors. The intent is that DetNet networks should be able to among vendors. In other words, vendors should be able to create
be created at lower cost and with greater diversity of available DetNet networks at lower cost and with greater diversity of available
devices than existing proprietary networks. devices than existing proprietary networks.
11.2. Scalable Size 11.2. Scalable Size
DetNet networks range in size from very small, e.g. inside a single DetNet networks range in size from very small (e.g., inside a single
industrial machine, to very large, for example a Utility Grid network industrial machine) to very large (e.g., a utility-grid network
spanning a whole country, and involving many "hops" over various spanning a whole country and involving many "hops" over various kinds
kinds of links for example radio repeaters, microwave linkes, fiber of links -- for example, radio repeaters, microwave links, or fiber
optic links, etc.. However recall that the scope of DetNet is optic links). However, recall that the scope of DetNet is confined
confined to networks that are centrally administered, and explicitly to networks that are centrally administered and thereby explicitly
excludes unbounded decentralized networks such as the Internet. excludes unbounded decentralized networks such as the Internet.
11.2.1. Scalable Number of Flows 11.2.1. Scalable Number of Flows
The number of flows in a given network application can potentially be The number of flows in a given network application can potentially be
large, and can potentially grow faster than the number of nodes and large and can potentially grow faster than the number of nodes and
hops. So the network should provide a sufficient (perhaps hops, so the network should provide a sufficient (perhaps
configurable) maximum number of flows for any given application. configurable) maximum number of flows for any given application.
11.3. Scalable Timing Parameters and Accuracy 11.3. Scalable Timing Parameters and Accuracy
11.3.1. Bounded Latency 11.3.1. Bounded Latency
The DetNet Data Flow Information Model is expected to provide means DetNet data-flow information models are expected to provide means to
to configure the network that include parameters for querying network configure the network that include parameters for querying network
path latency, requesting bounded latency for a given stream, path latency, requesting bounded latency for a given stream,
requesting worst case maximum and/or minimum latency for a given path requesting worst-case maximum and/or minimum latency for a given path
or stream, and so on. It is an expected case that the network may or stream, and so on. It is expected that the network may not be
not be able to provide a given requested service level, and if so the able to provide a given requested service level; if this is indeed
network control system should reply that the requested services is the case, the network control system should reply that the requested
not available (as opposed to accepting the parameter but then not services are not available (as opposed to accepting the parameter but
delivering the desired behavior). then not delivering the desired behavior).
11.3.2. Low Latency 11.3.2. Low Latency
Applications may require "extremely low latency" however depending on Various applications may state that they require "extremely low
the application these may mean very different latency values; for latency"; however, depending on the application, "extremely low" may
example "low latency" across a Utility grid network is on a different imply very different latency bounds. For example, "low latency"
time scale than "low latency" in a motor control loop in a small across a utility-grid network is a different order of magnitude of
machine. The intent is that the mechanisms for specifying desired latency values compared to "low latency" in a motor control loop in a
latency include wide ranges, and that architecturally there is small machine. It is intended that the mechanisms for specifying
nothing to prevent arbirtrarily low latencies from being implemented desired latency include wide ranges and that architecturally there is
nothing to prevent arbitrarily low latencies from being implemented
in a given network. in a given network.
11.3.3. Bounded Jitter (Latency Variation) 11.3.3. Bounded Jitter (Latency Variation)
As with the other Latency-related elements noted above, parameters As with the other latency-related elements noted above, parameters
should be available to determine or request the allowed variation in that can determine or request permitted variations in latency should
latency. be available.
11.3.4. Symmetrical Path Delays 11.3.4. Symmetrical Path Delays
Some applications would like to specify that the transit delay time Some applications would like to specify that the transit delay time
values be equal for both the transmit and return paths. values be equal for both the transmit path and the return path.
11.4. High Reliability and Availability 11.4. High Reliability and Availability
Reliablity is of critical importance to many DetNet applications, in Reliability is of critical importance to many DetNet applications,
which consequences of failure can be extraordinarily high in terms of because the consequences of failure can be extraordinarily high in
cost and even human life. DetNet based systems are expected to be terms of cost and even human life. DetNet-based systems are expected
implemented with essentially arbitrarily high availability (for to be implemented with essentially arbitrarily high availability --
example 99.9999% up time, or even 12 nines). The intent is that the for example, 99.9999% uptime (where 99.9999 means "six nines") or
DetNet designs should not make any assumptions about the level of even 12 nines. DetNet designs should not make any assumptions about
reliability and availability that may be required of a given system, the level of reliability and availability that may be required of a
and should define parameters for communicating these kinds of metrics given system and should define parameters for communicating these
within the network. kinds of metrics within the network.
A strategy used by DetNet for providing such extraordinarily high A strategy used by DetNet for providing such extraordinarily high
levels of reliability is to provide redundant paths that can be levels of reliability is to provide redundant paths so that a system
seamlessly switched between, while maintaining the required can seamlessly switch between the paths while maintaining its
performance of that system. required level of performance.
11.5. Security 11.5. Security
Security is of critical importance to many DetNet applications. A Security is of critical importance to many DetNet applications. A
DetNet network must be able to be made secure against devices DetNet network must have the ability to be made secure against device
failures, attackers, misbehaving devices, and so on. In a DetNet failures, attackers, misbehaving devices, and so on. In a DetNet
network the data traffic is expected to be be time-sensitive, thus in network, the data traffic is expected to be time sensitive; thus, in
addition to arriving with the data content as intended, the data must addition to arriving with the data content as intended, the data must
also arrive at the expected time. This may present "new" security also arrive at the expected time. This may present "new" security
challenges to implementers, and must be addressed accordingly. There challenges to implementers and must be addressed accordingly. There
are other security implications, including (but not limited to) the are other security implications, including (but not limited to) the
change in attack surface presented by packet replication and change in attack surface presented by PRE.
elimination.
11.6. Deterministic Flows 11.6. Deterministic Flows
Reserved bandwidth data flows must be isolated from each other and Reserved-bandwidth data flows must be isolated from each other and
from best-effort traffic, so that even if the network is saturated from best-effort traffic, so that even if the network is saturated
with best-effort (and/or reserved bandwidth) traffic, the configured with best-effort (and/or reserved-bandwidth) traffic, the configured
flows are not adversely affected. flows are not adversely affected.
12. Security Considerations 12. Security Considerations
This document covers a number of representative applications and This document covers a number of representative applications and
network scenarios that are expected to make use of DetNet network scenarios that are expected to make use of DetNet
technologies. Each of the potential DetNet uses cases will have technologies. Each of the potential DetNet use cases will have
security considerations from both the use-specific and DetNet security considerations from both the use-specific perspective and
technology perspectives. While some use-specific security the DetNet technology perspective. While some use-specific security
considerations are discussed above, a more comprehensive discussion considerations are discussed above, a more comprehensive discussion
of such considerations is captured in DetNet Security Considerations of such considerations is captured in [DetNet-Security]
[I-D.ietf-detnet-security]. Readers are encouraged to review this ("Deterministic Networking (DetNet) Security Considerations").
document to gain a more complete understanding of DetNet related Readers are encouraged to review [DetNet-Security] to gain a more
security considerations. complete understanding of DetNet-related security considerations.
13. Contributors
RFC7322 limits the number of authors listed on the front page of a
draft to a maximum of 5, far fewer than the 20 individuals below who
made important contributions to this draft. The editor wishes to
thank and acknowledge each of the following authors for contributing
text to this draft. See also Section 14.
Craig Gunther (Harman International)
10653 South River Front Parkway, South Jordan,UT 84095
phone +1 801 568-7675, email craig.gunther@harman.com
Pascal Thubert (Cisco Systems, Inc)
Building D, 45 Allee des Ormes - BP1200, MOUGINS
Sophia Antipolis 06254 FRANCE
phone +33 497 23 26 34, email pthubert@cisco.com
Patrick Wetterwald (Cisco Systems)
45 Allees des Ormes, Mougins, 06250 FRANCE
phone +33 4 97 23 26 36, email pwetterw@cisco.com
Jean Raymond (Hydro-Quebec)
1500 University, Montreal, H3A3S7, Canada
phone +1 514 840 3000, email raymond.jean@hydro.qc.ca
Jouni Korhonen (Broadcom Corporation)
3151 Zanker Road, San Jose, 95134, CA, USA
email jouni.nospam@gmail.com
Yu Kaneko (Toshiba)
1 Komukai-Toshiba-cho, Saiwai-ku, Kasasaki-shi, Kanagawa, Japan
email yu1.kaneko@toshiba.co.jp
Subir Das (Vencore Labs)
150 Mount Airy Road, Basking Ridge, New Jersey, 07920, USA
email sdas@appcomsci.com
Balazs Varga (Ericsson)
Konyves Kalman krt. 11/B, Budapest, Hungary, 1097
email balazs.a.varga@ericsson.com
Janos Farkas (Ericsson)
Konyves Kalman krt. 11/B, Budapest, Hungary, 1097
email janos.farkas@ericsson.com
Franz-Josef Goetz (Siemens)
Gleiwitzerstr. 555, Nurnberg, Germany, 90475
email franz-josef.goetz@siemens.com
Juergen Schmitt (Siemens)
Gleiwitzerstr. 555, Nurnberg, Germany, 90475
email juergen.jues.schmitt@siemens.com
Xavier Vilajosana (Worldsensing)
483 Arago, Barcelona, Catalonia, 08013, Spain
email xvilajosana@worldsensing.com
Toktam Mahmoodi (King's College London)
Strand, London WC2R 2LS, United Kingdom
email toktam.mahmoodi@kcl.ac.uk
Spiros Spirou (Intracom Telecom)
19.7 km Markopoulou Ave., Peania, Attiki, 19002, Greece
email spiros.spirou@gmail.com
Petra Vizarreta (Technical University of Munich)
Maxvorstadt, ArcisstraBe 21, Munich, 80333, Germany
email petra.stojsavljevic@tum.de
Daniel Huang (ZTE Corporation, Inc.)
No. 50 Software Avenue, Nanjing, Jiangsu, 210012, P.R. China
email huang.guangping@zte.com.cn
Xuesong Geng (Huawei Technologies)
email gengxuesong@huawei.com
Diego Dujovne (Universidad Diego Portales)
email diego.dujovne@mail.udp.cl
Maik Seewald (Cisco Systems)
email maseewal@cisco.com
14. Acknowledgments
14.1. Pro Audio
This section was derived from draft-gunther-detnet-proaudio-req-01.
The editors would like to acknowledge the help of the following
individuals and the companies they represent:
Jeff Koftinoff, Meyer Sound
Jouni Korhonen, Associate Technical Director, Broadcom
Pascal Thubert, CTAO, Cisco
Kieran Tyrrell, Sienda New Media Technologies GmbH
14.2. Utility Telecom
This section was derived from draft-wetterwald-detnet-utilities-reqs-
02.
Faramarz Maghsoodlou, Ph. D. IoT Connected Industries and Energy
Practice Cisco
Pascal Thubert, CTAO Cisco
The wind power generation use case has been extracted from the study
of Wind Farms conducted within the 5GPPP Virtuwind Project. The
project is funded by the European Union's Horizon 2020 research and
innovation programme under grant agreement No 671648 (VirtuWind).
14.3. Building Automation Systems
This section was derived from draft-bas-usecase-detnet-00.
14.4. Wireless for Industrial Applications
This section was derived from draft-thubert-6tisch-4detnet-01.
This specification derives from the 6TiSCH architecture, which is the
result of multiple interactions, in particular during the 6TiSCH
(bi)Weekly Interim call, relayed through the 6TiSCH mailing list at
the IETF.
The authors wish to thank: Kris Pister, Thomas Watteyne, Xavier
Vilajosana, Qin Wang, Tom Phinney, Robert Assimiti, Michael
Richardson, Zhuo Chen, Malisa Vucinic, Alfredo Grieco, Martin Turon,
Dominique Barthel, Elvis Vogli, Guillaume Gaillard, Herman Storey,
Maria Rita Palattella, Nicola Accettura, Patrick Wetterwald, Pouria
Zand, Raghuram Sudhaakar, and Shitanshu Shah for their participation
and various contributions.
14.5. Cellular Radio
This section was derived from draft-korhonen-detnet-telreq-00.
14.6. Industrial Machine to Machine (M2M) 13. IANA Considerations
The authors would like to thank Feng Chen and Marcel Kiessling for This document has no IANA actions.
their comments and suggestions.
14.7. Internet Applications and CoMP 14. Informative References
This section was derived from draft-zha-detnet-use-case-00 by Yiyong [Ahm14] Ahmed, M. and R. Kim, "Communication Network Architectures
Zha. for Smart-Wind Power Farms", Energies 2014, pp. 3900-3921,
DOI 10.3390/en7063900, June 2014.
This document has benefited from reviews, suggestions, comments and [Arch-for-6TiSCH]
proposed text provided by the following members, listed in Thubert, P., Ed., "An Architecture for IPv6 over the TSCH
alphabetical order: Jing Huang, Junru Lin, Lehong Niu and Oilver mode of IEEE 802.15.4", Work in Progress,
Huang. draft-ietf-6tisch-architecture-20, March 2019.
14.8. Network Slicing [BACnet-IP]
ASHRAE, "Annex J to ANSI/ASHRAE 135-1995 - BACnet/IP",
January 1999, <http://www.bacnet.org/Addenda/
Add-1995-135a.pdf>.
This section was written by Xuesong Geng, who would like to [BAS-DetNet]
acknowledge Norm Finn and Mach Chen for their useful comments. Kaneko, Y. and S. Das, "Building Automation Use Cases and
Requirements for Deterministic Networking", Work in
Progress, draft-bas-usecase-detnet-00, October 2015.
14.9. Mining [CoAP-6TiSCH]
Sudhaakar, R., Ed. and P. Zand, "6TiSCH Resource
Management and Interaction using CoAP", Work in Progress,
draft-ietf-6tisch-coap-03, March 2015.
This section was written by Diego Dujovne in conjunction with Xavier [CoMP] NGMN Alliance, "RAN EVOLUTION PROJECT COMP EVALUATION AND
Vilasojana. ENHANCEMENT", VERSION 2.0, NGMN Alliance, March 2015,
<https://www.ngmn.org/fileadmin/user_upload/
NGMN_RANEV_D3_CoMP_Evaluation_and_Enhancement_v2.0.pdf>.
14.10. Private Blockchain [Content_Protection]
Olsen, D., "1722a Content Protection", April 2012,
<http://grouper.ieee.org/groups/1722/contributions/2012/
avtp_dolsen_1722a_content_protection.pdf>.
This section was written by Daniel Huang. [CPRI] CPRI Cooperation, "Common Public Radio Interface (CPRI);
Interface Specification", CPRI Specification V6.1,
July 2014, <http://www.cpri.info/downloads/
CPRI_v_6_1_2014-07-01.pdf>.
15. IANA Considerations [DCI] Digital Cinema Initiatives, LLC, "DCI Specification,
Version 1.3", June 2018, <https://www.dcimovies.com/>.
This memo includes no requests from IANA. [Det-Fwd-PHB]
Shah, S. and P. Thubert, "Deterministic Forwarding PHB",
Work in Progress,
draft-svshah-tsvwg-deterministic-forwarding-04,
August 2015.
16. Informative References [DetNet-6TiSCH]
Thubert, P., Ed., "6TiSCH requirements for DetNet", Work
in Progress, draft-thubert-6tisch-4detnet-01, June 2015.
[Ahm14] Ahmed, M. and R. Kim, "Communication network architectures [DetNet-Arch]
for smart-wind power farms.", Energies, p. 3900-3921. , Finn, N., Thubert, P., Varga, B., and J. Farkas,
June 2014. "Deterministic Networking Architecture", Work in Progress,
draft-ietf-detnet-architecture-13, May 2019.
[bacnetip] [DetNet-Audio-Reqs]
ASHRAE, "Annex J to ANSI/ASHRAE 135-1995 - BACnet/IP", Gunther, C., Ed. and E. Grossman, Ed., "Deterministic
January 1999. Networking Professional Audio Requirements", Work in
Progress, draft-gunther-detnet-proaudio-req-01,
March 2015.
[CoMP] NGMN Alliance, "RAN EVOLUTION PROJECT COMP EVALUATION AND [DetNet-Mobile]
ENHANCEMENT", NGMN Alliance NGMN_RANEV_D3_CoMP_Evaluation_ Zha, Y., "Deterministic Networking Use Case in Mobile
and_Enhancement_v2.0, March 2015, Network", Work in Progress, draft-zha-detnet-use-case-00,
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[RFC3031] Rosen, E., Viswanathan, A., and R. Callon, "Multiprotocol [RFC3031] Rosen, E., Viswanathan, A., and R. Callon, "Multiprotocol
Label Switching Architecture", RFC 3031, Label Switching Architecture", RFC 3031,
DOI 10.17487/RFC3031, January 2001, DOI 10.17487/RFC3031, January 2001,
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[RFC3411] Harrington, D., Presuhn, R., and B. Wijnen, "An [RFC3411] Harrington, D., Presuhn, R., and B. Wijnen, "An
Architecture for Describing Simple Network Management Architecture for Describing Simple Network Management
Protocol (SNMP) Management Frameworks", STD 62, RFC 3411, Protocol (SNMP) Management Frameworks", STD 62, RFC 3411,
DOI 10.17487/RFC3411, December 2002, DOI 10.17487/RFC3411, December 2002,
skipping to change at page 83, line 34 skipping to change at page 88, line 5
IEEE 802.15.4e Time-Slotted Channel Hopping (TSCH) in the IEEE 802.15.4e Time-Slotted Channel Hopping (TSCH) in the
Internet of Things (IoT): Problem Statement", RFC 7554, Internet of Things (IoT): Problem Statement", RFC 7554,
DOI 10.17487/RFC7554, May 2015, DOI 10.17487/RFC7554, May 2015,
<https://www.rfc-editor.org/info/rfc7554>. <https://www.rfc-editor.org/info/rfc7554>.
[RFC8169] Mirsky, G., Ruffini, S., Gray, E., Drake, J., Bryant, S., [RFC8169] Mirsky, G., Ruffini, S., Gray, E., Drake, J., Bryant, S.,
and A. Vainshtein, "Residence Time Measurement in MPLS and A. Vainshtein, "Residence Time Measurement in MPLS
Networks", RFC 8169, DOI 10.17487/RFC8169, May 2017, Networks", RFC 8169, DOI 10.17487/RFC8169, May 2017,
<https://www.rfc-editor.org/info/rfc8169>. <https://www.rfc-editor.org/info/rfc8169>.
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Look into SCADA Network Traffic", IP Operations and SCADA Network Traffic", IP Network Operations and
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architecture and interfaces (Release 14)", 3GPP TR 38.801,
April 2017,
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SpecificationDetails.aspx?specificationId=3056>. SpecificationDetails.aspx?specificationId=3056>.
[TS23401] 3GPP, "General Packet Radio Service (GPRS) enhancements [TS23401] 3GPP, "General Packet Radio Service (GPRS) enhancements
for Evolved Universal Terrestrial Radio Access Network for Evolved Universal Terrestrial Radio Access Network
(E-UTRAN) access", 3GPP TS 23.401 10.10.0, March 2013. (E-UTRAN) access (Release 16)", 3GPP TS 23.401,
March 2019, <https://portal.3gpp.org/
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[TS23501] 3GPP, "System architecture for the 5G System (5GS)
(Release 15)", 3GPP TS 23.501, March 2019,
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(FDD)", 3GPP TS 25.104 3.14.0, March 2007. (FDD) (Release 16)", 3GPP TS 25.104, January 2019,
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[TS36104] 3GPP, "Evolved Universal Terrestrial Radio Access [TS36104] 3GPP, "Evolved Universal Terrestrial Radio Access
(E-UTRA); Base Station (BS) radio transmission and (E-UTRA); Base Station (BS) radio transmission and
reception", 3GPP TS 36.104 10.11.0, July 2013. reception (Release 16)", 3GPP TS 36.104, January 2019,
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[TS36133] 3GPP, "Evolved Universal Terrestrial Radio Access [TS36133] 3GPP, "Evolved Universal Terrestrial Radio Access
(E-UTRA); Requirements for support of radio resource (E-UTRA); Requirements for support of radio resource
management", 3GPP TS 36.133 12.7.0, April 2015. management (Release 16)", 3GPP TS 36.133, January 2019,
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[TS36211] 3GPP, "Evolved Universal Terrestrial Radio Access [TS36211] 3GPP, "Evolved Universal Terrestrial Radio Access
(E-UTRA); Physical channels and modulation", 3GPP (E-UTRA); Physical channels and modulation (Release 15)",
TS 36.211 10.7.0, March 2013. 3GPP TS 36.211, January 2019,
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SpecificationDetails.aspx?specificationId=2425>.
[TS36300] 3GPP, "Evolved Universal Terrestrial Radio Access (E-UTRA) [TS36300] 3GPP, "Evolved Universal Terrestrial Radio Access (E-UTRA)
and Evolved Universal Terrestrial Radio Access Network