draft-ietf-detnet-use-cases-06.txt   draft-ietf-detnet-use-cases-07.txt 
Internet Engineering Task Force E. Grossman, Ed. Internet Engineering Task Force E. Grossman, Ed.
Internet-Draft DOLBY Internet-Draft DOLBY
Intended status: Informational C. Gunther Intended status: Informational C. Gunther
Expires: September 5, 2016 HARMAN Expires: September 6, 2016 HARMAN
P. Thubert P. Thubert
P. Wetterwald P. Wetterwald
CISCO CISCO
J. Raymond J. Raymond
HYDRO-QUEBEC HYDRO-QUEBEC
J. Korhonen J. Korhonen
BROADCOM BROADCOM
Y. Kaneko Y. Kaneko
Toshiba Toshiba
S. Das S. Das
Applied Communication Sciences Applied Communication Sciences
Y. Zha Y. Zha
HUAWEI HUAWEI
B. Varga B. Varga
J. Farkas J. Farkas
Ericsson Ericsson
F. Goetz F. Goetz
J. Schmitt J. Schmitt
Siemens Siemens
March 4, 2016 March 5, 2016
Deterministic Networking Use Cases Deterministic Networking Use Cases
draft-ietf-detnet-use-cases-06 draft-ietf-detnet-use-cases-07
Abstract Abstract
This draft documents requirements in several diverse industries to This draft documents requirements in several diverse industries to
establish multi-hop paths for characterized flows with deterministic establish multi-hop paths for characterized flows with deterministic
properties. In this context deterministic implies that streams can properties. In this context deterministic implies that streams can
be established which provide guaranteed bandwidth and latency which be established which provide guaranteed bandwidth and latency which
can be established from either a Layer 2 or Layer 3 (IP) interface, can be established from either a Layer 2 or Layer 3 (IP) interface,
and which can co-exist on an IP network with best-effort traffic. and which can co-exist on an IP network with best-effort traffic.
skipping to change at page 2, line 20 skipping to change at page 2, line 20
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
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Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on September 5, 2016. This Internet-Draft will expire on September 6, 2016.
Copyright Notice Copyright Notice
Copyright (c) 2016 IETF Trust and the persons identified as the Copyright (c) 2016 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
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Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 5 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 5
2. Pro Audio Use Cases . . . . . . . . . . . . . . . . . . . . . 5 2. Pro Audio and Video . . . . . . . . . . . . . . . . . . . . . 5
2.1. Introduction . . . . . . . . . . . . . . . . . . . . . . 5 2.1. Use Case Description . . . . . . . . . . . . . . . . . . 5
2.2. Fundamental Stream Requirements . . . . . . . . . . . . . 6 2.1.1. Uninterrupted Stream Playback . . . . . . . . . . . . 6
2.2.1. Guaranteed Bandwidth . . . . . . . . . . . . . . . . 7 2.1.2. Synchronized Stream Playback . . . . . . . . . . . . 7
2.2.2. Bounded and Consistent Latency . . . . . . . . . . . 7 2.1.3. Sound Reinforcement . . . . . . . . . . . . . . . . . 7
2.2.2.1. Optimizations . . . . . . . . . . . . . . . . . . 8 2.1.4. Deterministic Time to Establish Streaming . . . . . . 8
2.3. Additional Stream Requirements . . . . . . . . . . . . . 9 2.1.5. Secure Transmission . . . . . . . . . . . . . . . . . 8
2.3.1. Deterministic Time to Establish Streaming . . . . . . 9 2.1.5.1. Safety . . . . . . . . . . . . . . . . . . . . . 8
2.3.2. Use of Unused Reservations by Best-Effort Traffic . . 9 2.1.5.2. Digital Rights Management (DRM) . . . . . . . . . 8
2.3.3. Layer 3 Interconnecting Layer 2 Islands . . . . . . . 10 2.2. Pro Audio Today . . . . . . . . . . . . . . . . . . . . . 9
2.3.4. Secure Transmission . . . . . . . . . . . . . . . . . 10 2.3. Pro Audio Future . . . . . . . . . . . . . . . . . . . . 9
2.3.5. Redundant Paths . . . . . . . . . . . . . . . . . . . 10 2.3.1. Layer 3 Interconnecting Layer 2 Islands . . . . . . . 9
2.3.6. Link Aggregation . . . . . . . . . . . . . . . . . . 11 2.3.2. High Reliability Stream Paths . . . . . . . . . . . . 9
2.3.7. Traffic Segregation . . . . . . . . . . . . . . . . . 11 2.3.3. Link Aggregation . . . . . . . . . . . . . . . . . . 10
2.3.7.1. Packet Forwarding Rules, VLANs and Subnets . . . 11 2.3.4. Integration of Reserved Streams into IT Networks . . 10
2.3.7.2. Multicast Addressing (IPv4 and IPv6) . . . . . . 11 2.3.5. Use of Unused Reservations by Best-Effort Traffic . . 10
2.4. Integration of Reserved Streams into IT Networks . . . . 12 2.3.6. Traffic Segregation . . . . . . . . . . . . . . . . . 10
2.5. Security Considerations . . . . . . . . . . . . . . . . . 12 2.3.6.1. Packet Forwarding Rules, VLANs and Subnets . . . 11
2.5.1. Denial of Service . . . . . . . . . . . . . . . . . . 12 2.3.6.2. Multicast Addressing (IPv4 and IPv6) . . . . . . 11
2.5.2. Control Protocols . . . . . . . . . . . . . . . . . . 12 2.3.7. Latency Optimization by a Central Controller . . . . 11
2.6. A State-of-the-Art Broadcast Installation Hits Technology 2.3.8. Reduced Device Cost Due To Reduced Buffer Memory . . 12
Limits . . . . . . . . . . . . . . . . . . . . . . . . . 13 2.4. Pro Audio Asks . . . . . . . . . . . . . . . . . . . . . 12
3. Electrical Utilities . . . . . . . . . . . . . . . . . . . . 13 3. Electrical Utilities . . . . . . . . . . . . . . . . . . . . 12
3.1. Use Case Description . . . . . . . . . . . . . . . . . . 13 3.1. Use Case Description . . . . . . . . . . . . . . . . . . 12
3.1.1. Transmission Use Cases . . . . . . . . . . . . . . . 13 3.1.1. Transmission Use Cases . . . . . . . . . . . . . . . 13
3.1.1.1. Protection . . . . . . . . . . . . . . . . . . . 13 3.1.1.1. Protection . . . . . . . . . . . . . . . . . . . 13
3.1.1.2. Intra-Substation Process Bus Communications . . . 19 3.1.1.2. Intra-Substation Process Bus Communications . . . 18
3.1.1.3. Wide Area Monitoring and Control Systems . . . . 20 3.1.1.3. Wide Area Monitoring and Control Systems . . . . 19
3.1.1.4. IEC 61850 WAN engineering guidelines requirement 3.1.1.4. IEC 61850 WAN engineering guidelines requirement
classification . . . . . . . . . . . . . . . . . 21 classification . . . . . . . . . . . . . . . . . 20
3.1.2. Generation Use Case . . . . . . . . . . . . . . . . . 22 3.1.2. Generation Use Case . . . . . . . . . . . . . . . . . 21
3.1.3. Distribution use case . . . . . . . . . . . . . . . . 23 3.1.3. Distribution use case . . . . . . . . . . . . . . . . 22
3.1.3.1. Fault Location Isolation and Service Restoration 3.1.3.1. Fault Location Isolation and Service Restoration
(FLISR) . . . . . . . . . . . . . . . . . . . . . 23 (FLISR) . . . . . . . . . . . . . . . . . . . . . 22
3.2. Electrical Utilities Today . . . . . . . . . . . . . . . 24 3.2. Electrical Utilities Today . . . . . . . . . . . . . . . 23
3.2.1. Security Current Practices and Limitations . . . . . 24 3.2.1. Security Current Practices and Limitations . . . . . 23
3.3. Electrical Utilities Future . . . . . . . . . . . . . . . 26 3.3. Electrical Utilities Future . . . . . . . . . . . . . . . 25
3.3.1. Migration to Packet-Switched Network . . . . . . . . 26 3.3.1. Migration to Packet-Switched Network . . . . . . . . 25
3.3.2. Telecommunications Trends . . . . . . . . . . . . . . 27 3.3.2. Telecommunications Trends . . . . . . . . . . . . . . 26
3.3.2.1. General Telecommunications Requirements . . . . . 27 3.3.2.1. General Telecommunications Requirements . . . . . 26
3.3.2.2. Specific Network topologies of Smart Grid 3.3.2.2. Specific Network topologies of Smart Grid
Applications . . . . . . . . . . . . . . . . . . 28 Applications . . . . . . . . . . . . . . . . . . 27
3.3.2.3. Precision Time Protocol . . . . . . . . . . . . . 29 3.3.2.3. Precision Time Protocol . . . . . . . . . . . . . 28
3.3.3. Security Trends in Utility Networks . . . . . . . . . 30 3.3.3. Security Trends in Utility Networks . . . . . . . . . 29
3.4. Electrical Utilities Asks . . . . . . . . . . . . . . . . 32 3.4. Electrical Utilities Asks . . . . . . . . . . . . . . . . 31
4. Building Automation Systems . . . . . . . . . . . . . . . . . 32 4. Building Automation Systems . . . . . . . . . . . . . . . . . 31
4.1. Use Case Description . . . . . . . . . . . . . . . . . . 32 4.1. Use Case Description . . . . . . . . . . . . . . . . . . 31
4.2. Building Automation Systems Today . . . . . . . . . . . . 32 4.2. Building Automation Systems Today . . . . . . . . . . . . 31
4.2.1. BAS Architecture . . . . . . . . . . . . . . . . . . 33 4.2.1. BAS Architecture . . . . . . . . . . . . . . . . . . 32
4.2.2. BAS Deployment Model . . . . . . . . . . . . . . . . 34 4.2.2. BAS Deployment Model . . . . . . . . . . . . . . . . 33
4.2.3. Use Cases for Field Networks . . . . . . . . . . . . 36 4.2.3. Use Cases for Field Networks . . . . . . . . . . . . 35
4.2.3.1. Environmental Monitoring . . . . . . . . . . . . 36 4.2.3.1. Environmental Monitoring . . . . . . . . . . . . 35
4.2.3.2. Fire Detection . . . . . . . . . . . . . . . . . 36 4.2.3.2. Fire Detection . . . . . . . . . . . . . . . . . 35
4.2.3.3. Feedback Control . . . . . . . . . . . . . . . . 37 4.2.3.3. Feedback Control . . . . . . . . . . . . . . . . 36
4.2.4. Security Considerations . . . . . . . . . . . . . . . 37 4.2.4. Security Considerations . . . . . . . . . . . . . . . 36
4.3. BAS Future . . . . . . . . . . . . . . . . . . . . . . . 37 4.3. BAS Future . . . . . . . . . . . . . . . . . . . . . . . 36
4.4. BAS Asks . . . . . . . . . . . . . . . . . . . . . . . . 38 4.4. BAS Asks . . . . . . . . . . . . . . . . . . . . . . . . 37
5. Wireless for Industrial . . . . . . . . . . . . . . . . . . . 38 5. Wireless for Industrial . . . . . . . . . . . . . . . . . . . 37
5.1. Use Case Description . . . . . . . . . . . . . . . . . . 38 5.1. Use Case Description . . . . . . . . . . . . . . . . . . 37
5.1.1. Network Convergence using 6TiSCH . . . . . . . . . . 39 5.1.1. Network Convergence using 6TiSCH . . . . . . . . . . 38
5.1.2. Common Protocol Development for 6TiSCH . . . . . . . 39 5.1.2. Common Protocol Development for 6TiSCH . . . . . . . 38
5.2. Wireless Industrial Today . . . . . . . . . . . . . . . . 40 5.2. Wireless Industrial Today . . . . . . . . . . . . . . . . 39
5.3. Wireless Industrial Future . . . . . . . . . . . . . . . 40 5.3. Wireless Industrial Future . . . . . . . . . . . . . . . 39
5.3.1. Unified Wireless Network and Management . . . . . . . 40 5.3.1. Unified Wireless Network and Management . . . . . . . 39
5.3.1.1. PCE and 6TiSCH ARQ Retries . . . . . . . . . . . 42 5.3.1.1. PCE and 6TiSCH ARQ Retries . . . . . . . . . . . 41
5.3.2. Schedule Management by a PCE . . . . . . . . . . . . 43 5.3.2. Schedule Management by a PCE . . . . . . . . . . . . 42
5.3.2.1. PCE Commands and 6TiSCH CoAP Requests . . . . . . 43 5.3.2.1. PCE Commands and 6TiSCH CoAP Requests . . . . . . 42
5.3.2.2. 6TiSCH IP Interface . . . . . . . . . . . . . . . 44 5.3.2.2. 6TiSCH IP Interface . . . . . . . . . . . . . . . 43
5.3.3. 6TiSCH Security Considerations . . . . . . . . . . . 44 5.3.3. 6TiSCH Security Considerations . . . . . . . . . . . 43
5.4. Wireless Industrial Asks . . . . . . . . . . . . . . . . 45 5.4. Wireless Industrial Asks . . . . . . . . . . . . . . . . 44
6. Cellular Radio Use Cases . . . . . . . . . . . . . . . . . . 45 6. Cellular Radio Use Cases . . . . . . . . . . . . . . . . . . 44
6.1. Use Case Description . . . . . . . . . . . . . . . . . . 45 6.1. Use Case Description . . . . . . . . . . . . . . . . . . 44
6.1.1. Network Architecture . . . . . . . . . . . . . . . . 45 6.1.1. Network Architecture . . . . . . . . . . . . . . . . 44
6.1.2. Time Synchronization Requirements . . . . . . . . . . 46 6.1.2. Time Synchronization Requirements . . . . . . . . . . 45
6.1.3. Time-Sensitive Stream Requirements . . . . . . . . . 48 6.1.3. Time-Sensitive Stream Requirements . . . . . . . . . 47
6.1.4. Security Considerations . . . . . . . . . . . . . . . 48 6.1.4. Security Considerations . . . . . . . . . . . . . . . 47
6.2. Cellular Radio Networks Today . . . . . . . . . . . . . . 49 6.2. Cellular Radio Networks Today . . . . . . . . . . . . . . 48
6.3. Cellular Radio Networks Future . . . . . . . . . . . . . 49 6.3. Cellular Radio Networks Future . . . . . . . . . . . . . 48
6.4. Cellular Radio Networks Asks . . . . . . . . . . . . . . 51 6.4. Cellular Radio Networks Asks . . . . . . . . . . . . . . 50
7. Cellular Coordinated Multipoint Processing (CoMP) . . . . . . 51 7. Cellular Coordinated Multipoint Processing (CoMP) . . . . . . 50
7.1. Use Case Description . . . . . . . . . . . . . . . . . . 51 7.1. Use Case Description . . . . . . . . . . . . . . . . . . 50
7.1.1. CoMP Architecture . . . . . . . . . . . . . . . . . . 52 7.1.1. CoMP Architecture . . . . . . . . . . . . . . . . . . 51
7.1.2. Delay Sensitivity in CoMP . . . . . . . . . . . . . . 53 7.1.2. Delay Sensitivity in CoMP . . . . . . . . . . . . . . 52
7.2. CoMP Today . . . . . . . . . . . . . . . . . . . . . . . 53 7.2. CoMP Today . . . . . . . . . . . . . . . . . . . . . . . 52
7.3. CoMP Future . . . . . . . . . . . . . . . . . . . . . . . 53 7.3. CoMP Future . . . . . . . . . . . . . . . . . . . . . . . 52
7.3.1. Mobile Industry Overall Goals . . . . . . . . . . . . 53 7.3.1. Mobile Industry Overall Goals . . . . . . . . . . . . 52
7.3.2. CoMP Infrastructure Goals . . . . . . . . . . . . . . 54 7.3.2. CoMP Infrastructure Goals . . . . . . . . . . . . . . 53
7.4. CoMP Asks . . . . . . . . . . . . . . . . . . . . . . . . 54 7.4. CoMP Asks . . . . . . . . . . . . . . . . . . . . . . . . 53
8. Industrial M2M . . . . . . . . . . . . . . . . . . . . . . . 55 8. Industrial M2M . . . . . . . . . . . . . . . . . . . . . . . 54
8.1. Use Case Description . . . . . . . . . . . . . . . . . . 55 8.1. Use Case Description . . . . . . . . . . . . . . . . . . 54
8.2. Industrial M2M Communication Today . . . . . . . . . . . 56 8.2. Industrial M2M Communication Today . . . . . . . . . . . 55
8.2.1. Transport Parameters . . . . . . . . . . . . . . . . 56 8.2.1. Transport Parameters . . . . . . . . . . . . . . . . 55
8.2.2. Stream Creation and Destruction . . . . . . . . . . . 57 8.2.2. Stream Creation and Destruction . . . . . . . . . . . 56
8.3. Industrial M2M Future . . . . . . . . . . . . . . . . . . 57 8.3. Industrial M2M Future . . . . . . . . . . . . . . . . . . 56
8.4. Industrial M2M Asks . . . . . . . . . . . . . . . . . . . 58 8.4. Industrial M2M Asks . . . . . . . . . . . . . . . . . . . 57
9. Internet-based Applications . . . . . . . . . . . . . . . . . 58 9. Internet-based Applications . . . . . . . . . . . . . . . . . 57
9.1. Use Case Description . . . . . . . . . . . . . . . . . . 58 9.1. Use Case Description . . . . . . . . . . . . . . . . . . 57
9.1.1. Media Content Delivery . . . . . . . . . . . . . . . 58 9.1.1. Media Content Delivery . . . . . . . . . . . . . . . 57
9.1.2. Online Gaming . . . . . . . . . . . . . . . . . . . . 58 9.1.2. Online Gaming . . . . . . . . . . . . . . . . . . . . 57
9.1.3. Virtual Reality . . . . . . . . . . . . . . . . . . . 58 9.1.3. Virtual Reality . . . . . . . . . . . . . . . . . . . 57
9.2. Internet-Based Applications Today . . . . . . . . . . . . 59 9.2. Internet-Based Applications Today . . . . . . . . . . . . 58
9.3. Internet-Based Applications Future . . . . . . . . . . . 59 9.3. Internet-Based Applications Future . . . . . . . . . . . 58
9.4. Internet-Based Applications Asks . . . . . . . . . . . . 59 9.4. Internet-Based Applications Asks . . . . . . . . . . . . 58
10. Use Case Common Elements . . . . . . . . . . . . . . . . . . 59 10. Use Case Common Elements . . . . . . . . . . . . . . . . . . 58
11. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 60 11. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 59
11.1. Pro Audio . . . . . . . . . . . . . . . . . . . . . . . 60 11.1. Pro Audio . . . . . . . . . . . . . . . . . . . . . . . 59
11.2. Utility Telecom . . . . . . . . . . . . . . . . . . . . 61 11.2. Utility Telecom . . . . . . . . . . . . . . . . . . . . 60
11.3. Building Automation Systems . . . . . . . . . . . . . . 61 11.3. Building Automation Systems . . . . . . . . . . . . . . 60
11.4. Wireless for Industrial . . . . . . . . . . . . . . . . 61 11.4. Wireless for Industrial . . . . . . . . . . . . . . . . 60
11.5. Cellular Radio . . . . . . . . . . . . . . . . . . . . . 61 11.5. Cellular Radio . . . . . . . . . . . . . . . . . . . . . 60
11.6. Industrial M2M . . . . . . . . . . . . . . . . . . . . . 61 11.6. Industrial M2M . . . . . . . . . . . . . . . . . . . . . 60
11.7. Internet Applications and CoMP . . . . . . . . . . . . . 61 11.7. Internet Applications and CoMP . . . . . . . . . . . . . 60
12. Informative References . . . . . . . . . . . . . . . . . . . 62 12. Informative References . . . . . . . . . . . . . . . . . . . 61
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 70 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 69
1. Introduction 1. Introduction
This draft presents use cases from diverse industries which have in This draft presents use cases from diverse industries which have in
common a need for deterministic streams, but which also differ common a need for deterministic streams, but which also differ
notably in their network topologies and specific desired behavior. notably in their network topologies and specific desired behavior.
Together, they provide broad industry context for DetNet and a Together, they provide broad industry context for DetNet and a
yardstick against which proposed DetNet designs can be measured (to yardstick against which proposed DetNet designs can be measured (to
what extent does a proposed design satisfy these various use cases?) what extent does a proposed design satisfy these various use cases?)
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o How would you like it to be addressed in the future? o How would you like it to be addressed in the future?
o What do you want the IETF to deliver? o What do you want the IETF to deliver?
The level of detail in each use case should be sufficient to express The level of detail in each use case should be sufficient to express
the relevant elements of the use case, but not more. the relevant elements of the use case, but not more.
At the end we consider the use cases collectively, and examine the At the end we consider the use cases collectively, and examine the
most significant goals they have in common. most significant goals they have in common.
2. Pro Audio Use Cases 2. Pro Audio and Video
2.1. Introduction
The professional audio and video industry includes music and film
content creation, broadcast, cinema, and live exposition as well as
public address, media and emergency systems at large venues
(airports, stadiums, churches, theme parks). These industries have
already gone through the transition of audio and video signals from
analog to digital, however the interconnect systems remain primarily
point-to-point with a single (or small number of) signals per link,
interconnected with purpose-built hardware.
These industries are now attempting to transition to packet based 2.1. Use Case Description
infrastructure for distributing audio and video in order to reduce
cost, increase routing flexibility, and integrate with existing IT
infrastructure.
However, there are several requirements for making a network the The professional audio and video industry ("ProAV") includes:
primary infrastructure for audio and video which are not met by
todays networks and these are our concern in this draft.
The principal requirement is that pro audio and video applications o Music and film content creation
become able to establish streams that provide guaranteed (bounded)
bandwidth and latency from the Layer 3 (IP) interface. Such streams
can be created today within standards-based layer 2 islands however
these are not sufficient to enable effective distribution over wider
areas (for example broadcast events that span wide geographical
areas).
Some proprietary systems have been created which enable deterministic o Broadcast
streams at layer 3 however they are engineered networks in that they o Cinema
require careful configuration to operate, often require that the
system be over designed, and it is implied that all devices on the
network voluntarily play by the rules of that network. To enable
these industries to successfully transition to an interoperable
multi-vendor packet-based infrastructure requires effective open
standards, and we believe that establishing relevant IETF standards
is a crucial factor.
It would be highly desirable if such streams could be routed over the o Live sound
open Internet, however even intermediate solutions with more limited
scope (such as enterprise networks) can provide a substantial
improvement over todays networks, and a solution that only provides
for the enterprise network scenario is an acceptable first step.
We also present more fine grained requirements of the audio and video o Public address, media and emergency systems at large venues
industries such as safety and security, redundant paths, devices with (airports, stadiums, churches, theme parks).
limited computing resources on the network, and that reserved stream
bandwidth is available for use by other best-effort traffic when that
stream is not currently in use.
2.2. Fundamental Stream Requirements These industries have already transitioned audio and video signals
from analog to digital. However, the digital interconnect systems
remain primarily point-to-point with a single (or small number of)
signals per link, interconnected with purpose-built hardware.
The fundamental stream properties are guaranteed bandwidth and These industries are now transitioning to packet-based infrastructure
deterministic latency as described in this section. Additional to reduce cost, increase routing flexibility, and integrate with
stream requirements are described in a subsequent section. existing IT infrastructure.
2.2.1. Guaranteed Bandwidth Today ProAV applications have no way to establish deterministic
streams from a standards-based Layer 3 (IP) interface, which is a
fundamental limitation to the use cases described here. Today
deterministic streams can be created within standards-based layer 2
LANs (e.g. using IEEE 802.1 AVB) however these are not routable via
IP and thus are not effective for distribution over wider areas (for
example broadcast events that span wide geographical areas).
Transmitting audio and video streams is unlike common file transfer It would be highly desirable if such streams could be routed over the
activities because guaranteed delivery cannot be achieved by re- open Internet, however solutions with more limited scope (e.g.
trying the transmission; by the time the missing or corrupt packet enterprise networks) would still provide a substantial improvement.
has been identified it is too late to execute a re-try operation and
stream playback is interrupted, which is unacceptable in for example
a live concert. In some contexts large amounts of buffering can be
used to provide enough delay to allow time for one or more retries,
however this is not an effective solution when live interaction is
involved, and is not considered an acceptable general solution for
pro audio and video. (Have you ever tried speaking into a microphone
through a sound system that has an echo coming back at you? It makes
it almost impossible to speak clearly).
Providing a way to reserve a specific amount of bandwidth for a given The following sections describe specific ProAV use cases.
stream is a key requirement.
2.2.2. Bounded and Consistent Latency 2.1.1. Uninterrupted Stream Playback
Latency in this context means the amount of time that passes between Transmitting audio and video streams for live playback is unlike
when a signal is sent over a stream and when it is received, for common file transfer because uninterrupted stream playback in the
example the amount of time delay between when you speak into a presence of network errors cannot be achieved by re-trying the
microphone and when your voice emerges from the speaker. Any delay transmission; by the time the missing or corrupt packet has been
longer than about 10-15 milliseconds is noticeable by most live identified it is too late to execute a re-try operation. Buffering
performers, and greater latency makes the system unusable because it can be used to provide enough delay to allow time for one or more
prevents them from playing in time with the other players (see slide retries, however this is not an effective solution in applications
6 of [SRP_LATENCY]). where large delays (latencies) are not acceptable (as discussed
below).
The 15ms latency bound is made even more challenging because it is Streams with guaranteed bandwidth can eliminate congestion on the
often the case in network based music production with live electric network as a cause of transmission errors that would lead to playback
instruments that multiple stages of signal processing are used, interruption. Use of redundant paths can further mitigate
connected in series (i.e. from one to the other for example from transmission errors to provide greater stream reliability.
guitar through a series of digital effects processors) in which case
the latencies add, so the latencies of each individual stage must all
together remain less than 15ms.
In some situations it is acceptable at the local location for content 2.1.2. Synchronized Stream Playback
from the live remote site to be delayed to allow for a statistically
acceptable amount of latency in order to reduce jitter. However,
once the content begins playing in the local location any audio
artifacts caused by the local network are unacceptable, especially in
those situations where a live local performer is mixed into the feed
from the remote location.
In addition to being bounded to within some predictable and Latency in this context is the time between when a signal is
acceptable amount of time (which may be 15 milliseconds or more or initially sent over a stream and when it is received. A common
less depending on the application) the latency also has to be example in ProAV is time-synchronizing audio and video when they take
consistent. For example when playing a film consisting of a video separate paths through the playback system. In this case the latency
stream and audio stream over a network, those two streams must be of both the audio and video streams must be bounded and consistent if
synchronized so that the voice and the picture match up. A common the sound is to remain matched to the movement in the video. A
tolerance for audio/video sync is one NTSC video frame (about 33ms) common tolerance for audio/video sync is one NTSC video frame (about
and to maintain the audience perception of correct lip sync the 33ms) and to maintain the audience perception of correct lip sync the
latency needs to be consistent within some reasonable tolerance, for latency needs to be consistent within some reasonable tolerance, for
example 10%. 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) is to enable measurement of the latency of each path, and
have the data sinks (for example speakers) buffer (delay) all packets have the data sinks (for example speakers) delay (buffer) all packets
on all but the slowest path. Each packet of each stream is assigned on all but the slowest path. Each packet of each stream is assigned
a presentation time which is based on the longest required delay. a presentation time which is based on the longest required delay.
This implies that all sinks must maintain a common time reference of This 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 any of 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.
2.2.2.1. Optimizations 2.1.3. Sound Reinforcement
The controller might also perform optimizations based on the
individual path delays, for example sinks that are closer to the
source can inform the controller that they can accept greater latency
since they will be buffering packets to match presentation times of
farther away sinks. The controller might then move a stream
reservation on a short path to a longer path in order to free up
bandwidth for other critical streams on that short path. See slides
3-5 of [SRP_LATENCY].
Additional optimization can be achieved in cases where sinks have Consider the latency (delay) from when a person speaks into a
differing latency requirements, for example in a live outdoor concert microphone to when their voice emerges from the speaker. If this
the speaker sinks have stricter latency requirements than the delay is longer than about 10-15 milliseconds it is noticeable and
recording hardware sinks. See slide 7 of [SRP_LATENCY]. can make a sound reinforcement system unusable (see slide 6 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).
Device cost can be reduced in a system with guaranteed reservations Note that the 15ms latency bound includes all parts of the signal
with a small bounded latency due to the reduced requirements for path, not just the network, so the network latency must be
buffering (i.e. memory) on sink devices. For example, a theme park significantly less than 15ms.
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
latency bounds and jitter caused by delivery, which depends on the
worst case segment of the end-to-end network path. For example on
todays open internet the latency is typically unacceptable for audio
and video streaming without many seconds of buffering. In such
scenarios a single gateway device at the local network that receives
the feed from the remote site would provide the expensive buffering
required to mask the latency and jitter issues associated with long
distance delivery. Sink devices in the local location would have no
additional buffering requirements, and thus no additional costs,
beyond those required for delivery of local content. The sink device
would be receiving the identical packets as those sent by the source
and would be unaware that there were any latency or jitter issues
along the path.
2.3. Additional Stream Requirements In some cases local performers must perform in synchrony with a
remote broadcast. In such cases the latencies of the broadcast
stream and the local performer must be adjusted to match each other,
with a worst case of one video frame (33ms for NTSC video).
The requirements in this section are more specific yet are common to In cases where audio phase is a consideration, for example beam-
multiple audio and video industry applications. forming using multiple speakers, latency requirements can be in the
10 microsecond range (1 audio sample at 96kHz).
2.3.1. Deterministic Time to Establish Streaming 2.1.4. Deterministic Time to Establish Streaming
Some audio systems installed in public environments (airports, Some audio systems installed in public environments (airports,
hospitals) have unique requirements with regards to health, safety hospitals) have unique requirements with regards to health, safety
and fire concerns. One such requirement is a maximum of 3 seconds and fire concerns. One such requirement is a maximum of 3 seconds
for a system to respond to an emergency detection and begin sending for a system to respond to an emergency detection and begin sending
appropriate warning signals and alarms without human intervention. appropriate warning signals and alarms without human intervention.
For this requirement to be met, the system must support a bounded and For this requirement to be met, the system must support a bounded and
acceptable time from a notification signal to specific stream acceptable time from a notification signal to specific stream
establishment. For further details see [ISO7240-16]. establishment. For further details see [ISO7240-16].
Similar requirements apply when the system is restarted after a power Similar requirements apply when the system is restarted after a power
cycle, cable re-connection, or system reconfiguration. cycle, cable re-connection, or system reconfiguration.
In many cases such re-establishment of streaming state must be In many cases such re-establishment of streaming state must be
achieved by the peer devices themselves, i.e. without a central achieved by the peer devices themselves, i.e. without a central
controller (since such a controller may only be present during controller (since such a controller may only be present during
initial network configuration). initial network configuration).
Video systems introduce related requirements, for example when Video systems introduce related requirements, for example when
transitioning from one camera feed to another. Such systems transitioning from one camera feed (video stream) to another (see
currently use purpose-built hardware to switch feeds smoothly, [STUDIO_IP] and [ESPN_DC2]).
however there is a current initiative in the broadcast industry to
switch to a packet-based infrastructure (see [STUDIO_IP] and the ESPN
DC2 use case described below).
2.3.2. Use of Unused Reservations by Best-Effort Traffic
In cases where stream bandwidth is reserved but not currently used
(or is under-utilized) that bandwidth must be available to best-
effort (i.e. non-time-sensitive) traffic. For example a single
stream may be nailed up (reserved) for specific media content that
needs to be presented at different times of the day, ensuring timely
delivery of that content, yet in between those times the full
bandwidth of the network can be utilized for best-effort tasks such
as file transfers.
This also addresses a concern of IT network administrators that are 2.1.5. Secure Transmission
considering adding reserved bandwidth traffic to their networks that
users will just reserve a ton of bandwidth and then never un-reserve
it even though they are not using it, and soon they will have no
bandwidth left.
2.3.3. Layer 3 Interconnecting Layer 2 Islands 2.1.5.1. Safety
As an intermediate step (short of providing guaranteed bandwidth Professional audio systems can include amplifiers that are capable of
across the open internet) it would be valuable to provide a way to generating hundreds or thousands of watts of audio power which if
connect multiple Layer 2 networks. For example layer 2 techniques used incorrectly can cause hearing damage to those in the vicinity.
could be used to create a LAN for a single broadcast studio, and Apart from the usual care required by the systems operators to
several such studios could be interconnected via layer 3 links. prevent such incidents, the network traffic that controls these
devices must be secured (as with any sensitive application traffic).
2.3.4. Secure Transmission 2.1.5.2. Digital Rights Management (DRM)
Digital Rights Management (DRM) is very important to the audio and Digital Rights Management (DRM) is very important to the audio and
video industries. Any time protected content is introduced into a video industries. Any time protected content is introduced into a
network there are DRM concerns that must be maintained (see network there are DRM concerns that must be maintained (see
[CONTENT_PROTECTION]). Many aspects of DRM are outside the scope of [CONTENT_PROTECTION]). Many aspects of DRM are outside the scope of
network technology, however there are cases when a secure link network technology, however there are cases when a secure link
supporting authentication and encryption is required by content supporting authentication and encryption is required by content
owners to carry their audio or video content when it is outside their owners to carry their audio or video content when it is outside their
own secure environment (for example see [DCI]). own secure environment (for example see [DCI]).
As an example, two techniques are Digital Transmission Content As an example, two techniques are Digital Transmission Content
Protection (DTCP) and High-Bandwidth Digital Content Protection Protection (DTCP) and High-Bandwidth Digital Content Protection
(HDCP). HDCP content is not approved for retransmission within any (HDCP). HDCP content is not approved for retransmission within any
other type of DRM, while DTCP may be retransmitted under HDCP. other type of DRM, while DTCP may be retransmitted under HDCP.
Therefore if the source of a stream is outside of the network and it Therefore if the source of a stream is outside of the network and it
uses HDCP protection it is only allowed to be placed on the network uses HDCP protection it is only allowed to be placed on the network
with that same HDCP protection. with that same HDCP protection.
2.3.5. Redundant Paths 2.2. Pro Audio Today
On-air and other live media streams must be backed up with redundant Some proprietary systems have been created which enable deterministic
links that seamlessly act to deliver the content when the primary streams at Layer 3 however they are "engineered networks" which
link fails for any reason. In point-to-point systems this is require careful configuration to operate, often require that the
system be over-provisioned, and it is implied that all devices on the
network voluntarily play by the rules of that network. To enable
these industries to successfully transition to an interoperable
multi-vendor packet-based infrastructure requires effective open
standards, and we believe that establishing relevant IETF standards
is a crucial factor.
2.3. Pro Audio Future
2.3.1. Layer 3 Interconnecting Layer 2 Islands
It would be valuable to enable IP to connect multiple Layer 2 LANs.
As an example, ESPN recently constructed a state-of-the-art 194,000
sq ft, $125 million broadcast studio called DC2. The DC2 network is
capable of handling 46 Tbps of throughput with 60,000 simultaneous
signals. Inside the facility are 1,100 miles of fiber feeding four
audio control rooms (see [ESPN_DC2] ).
In designing DC2 they replaced as much point-to-point technology as
they could with packet-based technology. They constructed seven
individual studios using layer 2 LANS (using IEEE 802.1 AVB) that
were entirely effective at routing audio within the LANs. However to
interconnect these layer 2 LAN islands together they ended up using
dedicated paths in a custom SDN (Software Defined Networking) router
because there is no standards-based routing solution available.
2.3.2. High Reliability Stream Paths
On-air and other live media streams are often backed up with
redundant links that seamlessly act to deliver the content when the
primary link fails for any reason. In point-to-point systems this is
provided by an additional point-to-point link; the analogous provided by an additional point-to-point link; the analogous
requirement in a packet-based system is to provide an alternate path requirement in a packet-based system is to provide an alternate path
through the network such that no individual link can bring down the through the network such that no individual link can bring down the
system. system.
2.3.6. Link Aggregation 2.3.3. Link Aggregation
For transmitting streams that require more bandwidth than a single For transmitting streams that require more bandwidth than a single
link in the target network can support, link aggregation is a link in the target network can support, link aggregation is a
technique for combining (aggregating) the bandwidth available on technique for combining (aggregating) the bandwidth available on
multiple physical links to create a single logical link of the multiple physical links to create a single logical link of the
required bandwidth. However, if aggregation is to be used, the required bandwidth. However, if aggregation is to be used, the
network controller (or equivalent) must be able to determine the network controller (or equivalent) must be able to determine the
maximum latency of any path through the aggregate link (see Bounded maximum latency of any path through the aggregate link.
and Consistent Latency section above).
2.3.7. Traffic Segregation 2.3.4. Integration of Reserved Streams into IT Networks
A commonly cited goal of moving to a packet based media
infrastructure is that costs can be reduced by using off the shelf,
commodity network hardware. In addition, economy of scale can be
realized by combining media infrastructure with IT infrastructure.
In keeping with these goals, stream reservation technology should be
compatible with existing protocols, and not compromise use of the
network for best effort (non-time-sensitive) traffic.
2.3.5. Use of Unused Reservations by Best-Effort Traffic
In cases where stream bandwidth is reserved but not currently used
(or is under-utilized) that bandwidth must be available to best-
effort (i.e. non-time-sensitive) traffic. For example a single
stream may be nailed up (reserved) for specific media content that
needs to be presented at different times of the day, ensuring timely
delivery of that content, yet in between those times the full
bandwidth of the network can be utilized for best-effort tasks such
as file transfers.
This also addresses a concern of IT network administrators that are
considering adding reserved bandwidth traffic to their networks that
("users will reserve large quantities of bandwidth and then never un-
reserve it even though they are not using it, and soon the network
will have no bandwidth left").
2.3.6. 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 one thousand seat theater can generate
enough broadcast traffic to overwhelm a low powered CPU. Thus an enough 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 There are many techniques that can be used to support this
requirement including (but not limited to) the following examples. requirement including (but not limited to) the following examples.
2.3.7.1. Packet Forwarding Rules, VLANs and Subnets 2.3.6.1. 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 using other means for example VLANs or IP subnets.
2.3.7.2. Multicast Addressing (IPv4 and IPv6) 2.3.6.2. 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 of the MAC Address forwarding nature of Layer 2 bridges it is
important that a multicast MAC address is only associated with one important that a multicast MAC address is only associated with one
stream. This will prevent reservations from forwarding packets from stream. This will prevent reservations from forwarding packets from
one stream down a path that has no interested sinks simply because one stream down a path that has no interested sinks simply because
there is another stream on that same path that shares the same there is another stream on that same path that shares the same
multicast MAC address. multicast MAC address.
Since each multicast MAC Address can represent 32 different IPv4 Since each multicast MAC Address can represent 32 different IPv4
multicast addresses there must be a process put in place to make sure multicast addresses there must be a process put in place to make sure
this does not occur. Requiring use of IPv6 address can achieve this, this does not occur. Requiring use of IPv6 address can achieve this,
however due to their continued prevalence, solutions that are however due to their continued prevalence, solutions that are
effective for IPv4 installations are also required. effective for IPv4 installations are also required.
2.4. Integration of Reserved Streams into IT Networks 2.3.7. Latency Optimization by a Central Controller
A commonly cited goal of moving to a packet based media A central network controller might also perform optimizations based
infrastructure is that costs can be reduced by using off the shelf, on the individual path delays, for example sinks that are closer to
commodity network hardware. In addition, economy of scale can be the source can inform the controller that they can accept greater
realized by combining media infrastructure with IT infrastructure. latency since they will be buffering packets to match presentation
In keeping with these goals, stream reservation technology should be times of farther away sinks. The controller might then move a stream
compatible with existing protocols, and not compromise use of the reservation on a short path to a longer path in order to free up
network for best effort (non-time-sensitive) traffic. bandwidth for other critical streams on that short path. See slides
3-5 of [SRP_LATENCY].
2.5. Security Considerations Additional optimization can be achieved in cases where sinks have
differing latency requirements, for example in a live outdoor concert
the speaker sinks have stricter latency requirements than the
recording hardware sinks. See slide 7 of [SRP_LATENCY].
Many industries that are moving from the point-to-point world to the 2.3.8. Reduced Device Cost Due To Reduced Buffer Memory
digital network world have little understanding of the pitfalls that
they can create for themselves with improperly implemented network
infrastructure. DetNet should consider ways to provide security
against DoS attacks in solutions directed at these markets. Some
considerations are given here as examples of ways that we can help
new users avoid common pitfalls.
2.5.1. Denial of Service Device cost can be reduced in a system with guaranteed reservations
with a small bounded latency due to the reduced requirements for
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;
in such cases the size of the buffers required is proportional to the
latency bounds and jitter caused by delivery, which depends on the
worst case segment of the end-to-end network path. For example on
todays open internet the latency is typically unacceptable for audio
and video streaming without many seconds of buffering. In such
scenarios a single gateway device at the local network that receives
the feed from the remote site would provide the expensive buffering
required to mask the latency and jitter issues associated with long
distance delivery. Sink devices in the local location would have no
additional buffering requirements, and thus no additional costs,
beyond those required for delivery of local content. The sink device
would be receiving the identical packets as those sent by the source
and would be unaware that there were any latency or jitter issues
along the path.
One security pitfall that this author is aware of involves the use of 2.4. Pro Audio Asks
technology that allows a presenter to throw the content from their
tablet or smart phone onto the A/V system that is then viewed by all
those in attendance. The facility introducing this technology was
quite excited to allow such modern flexibility to those who came to
speak. One thing they hadn't realized was that since no security was
put in place around this technology it left a hole in the system that
allowed other attendees to "throw" their own content onto the A/V
system.
2.5.2. Control Protocols o Layer 3 routing on top of AVB (and/or other high QoS networks)
Professional audio systems can include amplifiers that are capable of o Content delivery with bounded, lowest possible latency
generating hundreds or thousands of watts of audio power which if
used incorrectly can cause hearing damage to those in the vicinity.
Apart from the usual care required by the systems operators to
prevent such incidents, the network traffic that controls these
devices must be secured (as with any sensitive application traffic).
In addition, it would be desirable if the configuration protocols
that are used to create the network paths used by the professional
audio traffic could be designed to protect devices that are not meant
to receive high-amplitude content from having such potentially
damaging signals routed to them.
2.6. A State-of-the-Art Broadcast Installation Hits Technology Limits o IntServ and DiffServ integration with AVB (where practical)
ESPN recently constructed a state-of-the-art 194,000 sq ft, $125 o Single network for A/V and IT traffic
million broadcast studio called DC2. The DC2 network is capable of
handling 46 Tbps of throughput with 60,000 simultaneous signals.
Inside the facility are 1,100 miles of fiber feeding four audio
control rooms. (See details at [ESPN_DC2] ).
In designing DC2 they replaced as much point-to-point technology as o Standards-based, interoperable, multi-vendor
they possibly could with packet-based technology. They constructed
seven individual studios using layer 2 LANS (using IEEE 802.1 AVB)
that were entirely effective at routing audio within the LANs, and
they were very happy with the results, however to interconnect these
layer 2 LAN islands together they ended up using dedicated links
because there is no standards-based routing solution available.
This is the kind of motivation we have to develop these standards o IT department friendly
because customers are ready and able to use them.
o Enterprise-wide networks (e.g. 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.
Here we present use cases in Transmission, Generation and Here we present use cases in Transmission, Generation and
Distribution, including key timing and reliability metrics. We also Distribution, including key timing and reliability metrics. We also
discuss security issues and industry trends which affect the discuss security issues and industry trends which affect the
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