draft-ietf-teas-enhanced-vpn-05.txt   draft-ietf-teas-enhanced-vpn-06.txt 
TEAS working group J. Dong
Internet-Draft Huawei
Intended status: Informational S. Bryant
Expires: July 2020 Futurewei
Z. Li
China Mobile
T. Miyasaka
KDDI Corporation
Y.Lee
Sung Kyun Kwan University
February 18, 2020
A Framework for Enhanced Virtual Private Networks (VPN+) Services TEAS Working Group J. Dong
Internet-Draft Huawei
Intended status: Informational S. Bryant
Expires: January 14, 2021 Futurewei
Z. Li
China Mobile
T. Miyasaka
KDDI Corporation
Y. Lee
Samsung
July 13, 2020
draft-ietf-teas-enhanced-vpn-05 A Framework for Enhanced Virtual Private Networks (VPN+) Service
draft-ietf-teas-enhanced-vpn-06
Abstract Abstract
This document describes the framework for Enhanced Virtual Private This document describes the framework for Enhanced Virtual Private
Network (VPN+) service. The purpose is to support the needs of new Network (VPN+) service. The purpose is to support the needs of new
applications, particularly applications that are associated with 5G applications, particularly applications that are associated with 5G
services, by utilizing an approach that is based on existing VPN and services, by utilizing an approach that is based on existing VPN and
TE technologies and adds features that specific services require Traffic Engineering (TE) technologies and adds features that specific
over and above traditional VPNs. services require over and above traditional VPNs.
Typically, VPN+ will be used to form the underpinning of network Typically, VPN+ will be used to form the underpinning of network
slicing, but could also be of use in its own right providing slicing, but could also be of use in its own right providing enhanced
enhanced connectivity services between customer sites. connectivity services between customer sites.
It is envisaged that enhanced VPNs will be delivered using a It is envisaged that enhanced VPNs will be delivered using a
combination of existing, modified, and new networking technologies. combination of existing, modified, and new networking technologies.
This document provides an overview of relevant technologies and This document provides an overview of relevant technologies and
identifies some areas for potential new work. identifies some areas for potential new work.
It is not envisaged that quite large numbers of VPN+ services will be Comparing to traditional VPNs, It is not envisaged that quite large
deployed in a network and, in particular, it is not intended that numbers of VPN+ services will be deployed in a network. In other
all VPNs supported by a network will use VPN+ related techniques. word, it is not intended that all existing VPNs supported by a
network will use VPN+ related techniques.
Status of This Memo Status of This Memo
This Internet-Draft is submitted in full conformance with the This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79. provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
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Internet-Drafts are draft documents valid for a maximum of six Internet-Drafts are draft documents valid for a maximum of six months
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This Internet-Draft will expire on August 18, 2020. This Internet-Draft will expire on January 14, 2021.
Copyright Notice Copyright Notice
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Table of Contents Table of Contents
1. Introduction ................................................ 3 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Terminologies ............................................... 6 2. Terminologies . . . . . . . . . . . . . . . . . . . . . . . . 5
3. Overview of the Requirements ............................... 7 3. Overview of the Requirements . . . . . . . . . . . . . . . . 6
3.1. Isolation between Enhanced VPN Services ................ 7 3.1. Isolation between Enhanced VPN Services . . . . . . . . . 6
3.1.1. A Pragmatic Approach to Isolation ................. 8 3.1.1. A Pragmatic Approach to Isolation . . . . . . . . . . 8
3.2. Performance Guarantee .................................. 9 3.2. Performance Guarantee . . . . . . . . . . . . . . . . . . 9
3.3. Integration ........................................... 11 3.3. Integration . . . . . . . . . . . . . . . . . . . . . . . 10
3.3.1. Abstraction ...................................... 11 3.3.1. Abstraction . . . . . . . . . . . . . . . . . . . . . 11
3.4. Dynamic Management .................................... 12 3.4. Dynamic Management . . . . . . . . . . . . . . . . . . . 11
3.5. Customized Control .................................... 12 3.5. Customized Control . . . . . . . . . . . . . . . . . . . 12
3.6. Applicability ......................................... 13 3.6. Applicability . . . . . . . . . . . . . . . . . . . . . . 12
3.7. Inter-Domain and Inter-Layer Network .................. 13 3.7. Inter-Domain and Inter-Layer Network . . . . . . . . . . 12
4. Architecture of Enhanced VPN ............................... 13 4. Architecture of Enhanced VPN . . . . . . . . . . . . . . . . 13
4.1. Layered Architecture ................................. 15 4.1. Layered Architecture . . . . . . . . . . . . . . . . . . 14
4.2. Multi-Point to Multi-Point (MP2MP) Connectivity ....... 17 4.2. Multi-Point to Multi-Point (MP2MP) Connectivity . . . . . 17
4.3. Application Specific Network Types .................... 18 4.3. Application Specific Network Types . . . . . . . . . . . 17
4.4. Scaling Considerations ................................ 18 4.4. Scaling Considerations . . . . . . . . . . . . . . . . . 17
5. Candidate Technologies ..................................... 19 5. Candidate Technologies . . . . . . . . . . . . . . . . . . . 18
5.1. Layer-Two Data Plane .................................. 19 5.1. Layer-Two Data Plane . . . . . . . . . . . . . . . . . . 18
5.1.1. Flexible Ethernet ................................ 19 5.1.1. Flexible Ethernet . . . . . . . . . . . . . . . . . . 18
5.1.2. Dedicated Queues ................................. 20 5.1.2. Dedicated Queues . . . . . . . . . . . . . . . . . . 19
5.1.3. Time Sensitive Networking ........................ 20 5.1.3. Time Sensitive Networking . . . . . . . . . . . . . . 19
5.2. Layer-Three Data Plane ................................ 21 5.2. Layer-Three Data Plane . . . . . . . . . . . . . . . . . 20
5.2.1. Deterministic Networking ......................... 21 5.2.1. Deterministic Networking . . . . . . . . . . . . . . 20
5.2.2. MPLS Traffic Engineering (MPLS-TE) ............... 21 5.2.2. MPLS Traffic Engineering (MPLS-TE) . . . . . . . . . 20
5.2.3. Segment Routing .................................. 21 5.2.3. Segment Routing . . . . . . . . . . . . . . . . . . . 20
5.3. Non-Packet Data Plane ................................. 22 5.3. Non-Packet Data Plane . . . . . . . . . . . . . . . . . . 21
5.4. Control Plane ......................................... 22 5.4. Control Plane . . . . . . . . . . . . . . . . . . . . . . 21
5.5. Management Plane ...................................... 23 5.5. Management Plane . . . . . . . . . . . . . . . . . . . . 22
5.6. Applicability of Service Data Models to Enhanced VPN .. 23 5.6. Applicability of Service Data Models to Enhanced VPN . . 22
5.6.1. Enhanced VPN Delivery in the ACTN Architecture ... 24 5.6.1. Network Slice Delivery via Coordinated Service Data
5.6.2. Enhanced VPN Features with Service Data Models ... 25 Models . . . . . . . . . . . . . . . . . . . . . . . 23
5.6.3. 5G Transport Service Delivery via Coordinated Data 6. Scalability Considerations . . . . . . . . . . . . . . . . . 24
Modules ................................................. 27 6.1. Maximum Stack Depth of SR . . . . . . . . . . . . . . . . 25
6. Scalability Considerations ................................. 29 6.2. RSVP Scalability . . . . . . . . . . . . . . . . . . . . 25
6.1. Maximum Stack Depth of SR ............................. 30 6.3. SDN Scaling . . . . . . . . . . . . . . . . . . . . . . . 25
6.2. RSVP Scalability ...................................... 30 7. OAM Considerations . . . . . . . . . . . . . . . . . . . . . 25
6.3. SDN Scaling ........................................... 30 8. Telemetry Considerations . . . . . . . . . . . . . . . . . . 26
7. OAM Considerations ......................................... 30 9. Enhanced Resiliency . . . . . . . . . . . . . . . . . . . . . 26
8. Telemetry Considerations ................................... 31 10. Operational Considerations . . . . . . . . . . . . . . . . . 27
9. Enhanced Resiliency ........................................ 31 11. Security Considerations . . . . . . . . . . . . . . . . . . . 27
10. Operational Considerations ................................ 33 12. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 28
11. Security Considerations ................................... 33 13. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 28
12. IANA Considerations ....................................... 33 14. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 29
13. Contributors .............................................. 34 15. References . . . . . . . . . . . . . . . . . . . . . . . . . 29
14. Acknowledgments ........................................... 34 15.1. Normative References . . . . . . . . . . . . . . . . . . 29
15. References ................................................ 34 15.2. Informative References . . . . . . . . . . . . . . . . . 30
15.1. Normative References ................................. 34 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 35
15.2. Informative References ............................... 36
Authors' Addresses ............................................ 40
1. Introduction 1. Introduction
Virtual private networks (VPNs) have served the industry well as a Virtual private networks (VPNs) have served the industry well as a
means of providing different groups of users with logically isolated means of providing different groups of users with logically isolated
connectivity over a common network. The common or base network that connectivity over a common network. The common or base network that
is used to provide the VPNs is often referred to as the underlay, is used to provide the VPNs is often referred to as the underlay, and
and the VPN is often called an overlay. the VPN is often called an overlay.
Customers of a network operator may request a connectivity services Customers of a network operator may request a connectivity services
with advanced characteristics such as enhanced isolation from other with advanced characteristics such as enhanced isolation from other
services so that changes in some other service (such as changes in services so that changes in some other service (such as changes in
network load, or events such as congestion or outages) have no or network load, or events such as congestion or outages) have no or
acceptable effect on the throughput or latency of the services acceptable effect on the throughput or latency of the services
provided to the customer. These services are "enhanced VPNs" (known provided to the customer. These services are "enhanced VPNs" (known
as VPN+) in that they are similar to VPN services as they provide as VPN+) in that they are similar to VPN services as they provide the
the customer with required connectivity, but have enhanced customer with required connectivity, but have enhanced
characteristics. characteristics.
Driven largely by needs surfacing from 5G, the concept of network Driven largely by needs surfacing from 5G, the concept of network
slicing has gained traction [NGMN-NS-Concept] [TS23501] [TS28530] slicing has gained traction [NGMN-NS-Concept] [TS23501] [TS28530]
[BBF-SD406]. According to [TS28530], a 5G end-to-end network slice [BBF-SD406]. According to [TS28530], a 5G end-to-end network slice
consists of three major types network segments: Radio Access Network consists of three major types network segments: Radio Access Network
(RAN), Transport Network (TN) and Mobile Core Network (CN). The (RAN), Transport Network (TN) and Mobile Core Network (CN). The
transport network provides the required connectivity between transport network provides the required connectivity between
different entities in RAN and CN segments of an end-to-end network different entities in RAN and CN segments of an end-to-end network
slice, with specific performance commitment. slice, with specific performance commitment.
A transport network slice is a virtual (logical) network with a A transport network slice is a virtual (logical) network with a
particular network topology and a set of shared or dedicated network particular network topology and a set of shared or dedicated network
resources, which are used to provide the network slice consumer with resources, which are used to provide the network slice consumer with
the required connectivity, appropriate isolation and specific the required connectivity, appropriate isolation and specific Service
Service Level Agreement (SLA) or Service Level Objective (SLO). Level Objective (SLO).
A transport network slice could span multiple technologies (such as A transport network slice could span multiple technologies (such as
IP or Optical) and multiple administrative domains. Depending on the IP or Optical) and multiple administrative domains. Depending on the
consumer's requirement, a transport network slice could be isolated consumer's requirement, a transport network slice could be isolated
from other, often concurrent transport network slices in terms of from other, often concurrent transport network slices in terms of
data plane, control plane, and management plane resources. data plane, control plane, and management plane resources.
In this document the term "network slice" refers to a transport In this document the term "network slice" refers to a transport
network slice, and is considered as one typical use case of enhanced network slice, and is considered as one typical use case of enhanced
VPN. VPN.
Network slicing builds on the concept of resource management, Network slicing builds on the concept of resource management, network
network virtualization, and abstraction to provide performance virtualization, and abstraction to provide performance assurance,
assurance, flexibility, programmability and modularity. It may use flexibility, programmability and modularity. It may use techniques
techniques such as Software Defined Networking (SDN) [RFC7149], such as Software Defined Networking (SDN) [RFC7149], network
network abstraction [RFC7926] and Network Function Virtualization abstraction [RFC7926] and Network Function Virtualization (NFV)
(NFV) [RFC8172] [RFC8568] to create multiple logical (virtual) [RFC8172] [RFC8568] to create multiple logical (virtual) networks,
networks, each tailored for a set of services or a particular tenant each tailored for a set of services or a particular tenant or a group
or a group of tenants that share the same or similar set of of tenants that share the same or similar set of requirements, on top
requirements, on top of a common network. How the network slices of a common network. How the network slices are engineered can be
are engineered can be deployment-specific. deployment-specific.
VPN+ could be used to form the underpinning of transport network VPN+ could be used to form the underpinning of transport network
slice, but could also be of use in general cases providing enhanced slice, but could also be of use in general cases providing enhanced
connectivity services between customer sites. connectivity services between customer sites.
The requirement of enhanced VPN services cannot be met by simple The requirement of enhanced VPN services cannot be met by simple
overlay networks, as they require tighter coordination and overlay networks, as they require tighter coordination and
integration between the underlay and the overlay network. VPN+ is integration between the underlay and the overlay network. VPN+ is
built from a VPN overlay and a underlying Virtual Transport Network built from a VPN overlay and a underlying Virtual Transport Network
(VTN) which has a customized network topology and a set of dedicated (VTN) which has a customized network topology and a set of dedicated
or shared network resources. It may optionally include a set of or shared network resources. It may optionally include a set of
invoked service functions allocated from the underlay network. Thus invoked service functions allocated from the underlay network. Thus
an enhanced VPN can achieve greater isolation with strict an enhanced VPN can achieve greater isolation with strict performance
performance guarantees. These new properties, which have general guarantees. These new properties, which have general applicability,
applicability, may also be of interest as part of a network slicing may also be of interest as part of a network slicing solution. It is
solution. It is not envisaged that VPN+ services will replace not envisaged that VPN+ services will replace traditional VPN
traditional VPN services that can continue to be deployed using pre- services that can continue to be deployed using pre- existing
existing mechanisms. mechanisms.
This document specifies a framework for using This document specifies a framework for using existing, modified, and
existing, modified, and potential new technologies as components to potential new technologies as components to provide a VPN+ service.
provide a VPN+ service. Specifically we are concerned with: Specifically we are concerned with:
o The design of the enhanced data plane. o The design of the enhanced data plane.
o The necessary protocols in both the underlay and the overlay o The necessary protocols in both the underlay and the overlay of
of the enhanced VPN. the enhanced VPN.
o The mechanisms to achieve integration between overlay and o The mechanisms to achieve integration between overlay and
underlay. underlay.
o The necessary Operation, Administration, and Management (OAM) o The necessary Operation, Administration, and Management (OAM)
methods to instrument an enhanced VPN to make sure that the required methods to instrument an enhanced VPN to make sure that the
Service Level Agreement (SLA) is met, and to take any corrective required Service Level Agreement (SLA) is met, and to take any
action to avoid SLA violation, such as switching to an alternate corrective action to avoid SLA violation, such as switching to an
path. alternate path.
The required layered network structure to achieve this is shown in The required layered network structure to achieve this is shown in
Section 4.1. Section 4.1.
Note that, in this document, the relationship of the four terms Note that, in this document, the relationship of the four terms
"VPN", "Enhanced VPN" (or "VPN+"), "Virtual Transport Network (VTN)", "VPN", "VPN+", "VTN", and "Transport Network Slice" are described as
and "Network Slice" are described as below: below:
o An enhanced VPN (VPN+) can be considered as an evolution of o A VPN refers to the overlay virtual private network which provides
VPN service, but with additional service-specific commitments. Thus, the required service connectivity and traffic separation between
care must be taken with the term "VPN" to distinguish normal or different VPN customers.
legacy VPNs from VPN+ services.
o A Virtual Transport Network (VTN) is a virtual underlay o A Virtual Transport Network (VTN) is a virtual underlay network
network that connects customer edge points with the additional that connects customer edge points with the additional capability
capability of providing the isolation and performance of providing the isolation and performance characteristics
characteristics required by an enhanced VPN customer. required by an enhanced VPN customer.
o An enhanced VPN (VPN+) is made by integrating an overlay VPN o An enhanced VPN (VPN+) can be considered as an evolution of VPN
and an VTN with a set of network resources allocated in the underlay service, but with additional service-specific commitments. An
network. enhanced VPN (VPN+) is made by integrating an overlay VPN and a
VTN with a set of network resources allocated in the underlay
network.
o A network slice in transport network could be provided with an o A transport network slice could be provided with an enhanced VPN
enhanced VPN (VPN+). (VPN+).
2. Terminologies 2. Terminologies
The following terms are used in this document. Some of them are The following terms are used in this document. Some of them are
newly defined, some others reference existing definitions: newly defined, some others reference existing definitions:
ACTN: Abstraction and Control of TE Networks [RFC8453] ACTN: Abstraction and Control of TE Networks [RFC8453]
Detnet: Deterministic Networking [DETNET] Detnet: Deterministic Networking [DETNET]
FlexE: Flexible Ethernet [FLEXE] FlexE: Flexible Ethernet [FLEXE]
TSN: Time Sensitive Networking [TSN] TSN: Time Sensitive Networking [TSN]
VN: Virtual Network [I-D.ietf-teas-actn-vn-yang] VN: Virtual Network [I-D.ietf-teas-actn-vn-yang]
VPN: Virtual Private Network. IPVPN is defined in [RFC2764], L2VPN VPN: Virtual Private Network. IPVPN is defined in [RFC2764], L2VPN
is defined in [RFC4664] is defined in [RFC4664].
VPN+: Enhanced VPN service. An enhanced VPN service (VPN+) can be VPN+: Enhanced VPN service. An enhanced VPN service (VPN+) can be
considered as an evolution of VPN service, but with additional considered as an evolution of VPN service, but with additional
service-specific commitments such as enhanced isolation and service-specific commitments such as enhanced isolation and
performance guarantee. performance guarantee.
VTP: Virtual Transport Path. A VTP is a virtual underlay path which VTP: Virtual Transport Path. A VTP is a virtual underlay path which
connects two customer edge points with the capability of providing connects two customer edge points with the capability of providing
the isolation and performance characteristics required by an the isolation and performance characteristics required by an enhanced
enhanced VPN customer. A VTP usually has a customized path with a VPN customer. A VTP usually has a customized path with a set of
set of reserved network resources along the path. reserved network resources along the path.
VTN: Virtual Transport Network. A VTN is a virtual underlay network VTN: Virtual Transport Network. A VTN is a virtual underlay network
that connects customer edge points with the capability of providing that connects customer edge points with the capability of providing
the isolation and performance characteristics required by an the isolation and performance characteristics required by an enhanced
enhanced VPN customer. A VTN usually has a customized topology and a VPN customer. A VTN usually has a customized topology and a set of
set of dedicated or shared network resources. dedicated or shared network resources.
3. Overview of the Requirements 3. Overview of the Requirements
In this section we provide an overview of the requirements of an In this section we provide an overview of the requirements of an
enhanced VPN service. enhanced VPN service.
3.1. Isolation between Enhanced VPN Services 3.1. Isolation between Enhanced VPN Services
One element of the SLA demanded for an enhanced VPN is a guarantee One element of the SLA demanded for an enhanced VPN is a guarantee
that the service offered to the customer will not be perturbed by that the service offered to the customer will not be perturbed by any
any other traffic flows in the network. One way for a service other traffic flows in the network. One way for a service provider
provider to guarantee the customer's SLA is by controlling the to guarantee the customer's SLA is by controlling the degree of
degree of isolation from other services in the network. Isolation isolation from other services in the network. Isolation is a feature
is a feature that can be requested by customers. There are different that can be requested by customers. There are different grades of
grades of how isolation may be enabled by a network operator and how isolation may be enabled by a network operator and that may
that may result in different levels of service perceived by the result in different levels of service perceived by the customer.
customer. These range from simple separation of service traffic on These range from simple separation of service traffic on delivery
delivery (ensuring that traffic is not delivered to the wrong (ensuring that traffic is not delivered to the wrong customer), all
customer), all the way to complete separation within the underlay so the way to complete separation within the underlay so that the
that the traffic from different services use distinct network traffic from different services use distinct network resources.
resources.
The terms hard and soft isolation are used to identify different The terms hard and soft isolation are used to illustrate different
levels of isolation. A VPN has soft isolation if the traffic of one levels of isolation. A VPN has soft isolation if the traffic of one
VPN cannot be received by the customers of another VPN. Both IP and VPN cannot be received by the customers of another VPN. Both IP and
MPLS VPNs are examples of VPNs with soft isolation: the network MPLS VPNs are examples of VPNs with soft isolation: the network
delivers the traffic only to the required VPN endpoints. However, delivers the traffic only to the required VPN endpoints. However,
with soft isolation, traffic from VPNs and regular non-VPN traffic with soft isolation, traffic from VPNs and regular non-VPN traffic
may congest the network resulting in packet loss and delay for other may congest the network resulting in packet loss and delay for other
VPNs operating normally. The ability for a VPN service or a group VPNs operating normally. The ability for a VPN service or a group of
of VPN services to be sheltered from this effect is called hard VPN services to be sheltered from this effect is called hard
isolation, and this property is required by some applications. Hard isolation, and this property is required by some applications. Hard
isolation is needed so that applications with exacting requirements isolation is needed so that applications with exacting requirements
can function correctly, despite other demands (perhaps a burst of can function correctly, despite other demands (perhaps a burst of
traffic in another VPN) competing for the underlying resources. In traffic in another VPN) competing for the underlying resources. In
practice isolation may be offered as a spectrum between soft and practice isolation may be offered as a spectrum between soft and
hard, and in some cases soft and hard isolation may be used in a hard, and in some cases soft and hard isolation may be used in a
hierarchical manner. An operator may offer its customers a choice hierarchical manner. An operator may offer its customers a choice of
of different degrees of isolation ranging from soft isolation up to different degrees of isolation ranging from soft isolation up to hard
hard isolation. isolation.
An example of the requirement for hard isolation is a network An example of the requirement for hard isolation is a network
supporting both emergency services and public broadband multi-media supporting both emergency services and public broadband multi-media
services. During a major incident the VPNs supporting these services. During a major incident the VPNs supporting these services
services would both be expected to experience high data volumes, and would both be expected to experience high data volumes, and it is
it is important that both make progress in the transmission of their important that both make progress in the transmission of their data.
data. In these circumstances the VPN services would require an In these circumstances the VPN services would require an appropriate
appropriate degree of isolation to be able to continue to operate degree of isolation to be able to continue to operate acceptably. On
acceptably. On the other hand, VPNs servicing ordinary bulk data the other hand, VPNs servicing ordinary bulk data may expect to
may expect to contest for network resources and queue packets so contest for network resources and queue packets so that traffic is
that traffic is delivered within SLAs, but with some potential delivered within SLAs, but with some potential delays and
delays and interference. interference.
In order to provide the required level of isolation, resources may In order to provide the required level of isolation, resources may
have to be reserved in the data plane of the underlay network and have to be reserved in the data plane of the underlay network and
dedicated to traffic from a specific VPN or a specific group of VPNs dedicated to traffic from a specific VPN or a specific group of VPNs
to form different enhanced VPNs in the network. This may introduce to form different enhanced VPNs in the network. This may introduce
scalability concerns, thus some trade-off needs to be considered to scalability concerns, thus some trade-off needs to be considered to
provide the required isolation between some enhanced VPNs while provide the required isolation between some enhanced VPNs while still
still allowing reasonable sharing. allowing reasonable sharing.
An optical layer can offer a high degree of isolation, at the cost An optical layer can offer a high degree of isolation, at the cost of
of allocating resources on a long term and end-to-end basis. On the allocating resources on a long term and end-to-end basis. On the
other hand, where adequate isolation can be achieved at the packet other hand, where adequate isolation can be achieved at the packet
layer, this permits the resources to be shared amongst a group of layer, this permits the resources to be shared amongst a group of
services and only dedicated to a service on a temporary basis. services and only dedicated to a service on a temporary basis.
There are several new technologies that provide some assistance with There are several new technologies that provide some assistance with
these data plane issues. Firstly there is the IEEE project on Time these data plane issues. Firstly there is the IEEE project on Time
Sensitive Networking [TSN] which introduces the concept of packet Sensitive Networking [TSN] which introduces the concept of packet
scheduling of delay and loss sensitive packets. Then there is scheduling of delay and loss sensitive packets. Then there is
[FLEXE] which provides the ability to multiplex multiple channels [FLEXE] which provides the ability to multiplex multiple channels
over one or more Ethernet links in a way that provides hard over one or more Ethernet links in a way that provides hard
isolation. Finally there are advanced queueing approaches which isolation. Finally there are advanced queueing approaches which
allow the construction of virtual sub-interfaces, each of which is allow the construction of virtual sub-interfaces, each of which is
provided with dedicated resource in a shared physical interface. provided with dedicated resource in a shared physical interface.
These approaches are described in more detail later in this document. These approaches are described in more detail later in this document.
Section 3.1.1 explores pragmatic approaches to isolation in packet Section 3.1.1 explores pragmatic approaches to isolation in packet
networks. networks.
3.1.1. A Pragmatic Approach to Isolation 3.1.1. A Pragmatic Approach to Isolation
A key question is whether it is possible to achieve hard isolation A key question is whether it is possible to achieve hard isolation in
in packet networks that were never designed to support hard packet networks that were never designed to support hard isolation.
isolation. On the contrary, they were designed to provide On the contrary, they were designed to provide statistical
statistical multiplexing, a significant economic advantage when multiplexing, a significant economic advantage when compared to a
compared to a dedicated, or a Time Division Multiplexing (TDM) dedicated, or a Time Division Multiplexing (TDM) network. However,
network. However, there is no need to provide any harder isolation there is no need to provide any harder isolation than is required by
than is required by the applications. An approximation to this the applications. An approximation to this requirement is sufficient
requirement is sufficient in most cases. Pseudowires [RFC3985] in most cases. Pseudowires[RFC3985] emulate services that would have
emulate services that would have had hard isolation in their native had hard isolation in their native form.
form.
This spectrum of isolation is shown in Figure 1: This spectrum of isolation is shown in Figure 1:
O=================================================O O=================================================O
| \---------------v---------------/ | \---------------v---------------/
Statistical Pragmatic Absolute Statistical Pragmatic Absolute
Multiplexing Isolation Isolation Multiplexing Isolation Isolation
(Traditional VPNs) (Enhanced VPN) (Dedicated Network) (Traditional VPNs) (Enhanced VPN) (Dedicated Network)
Figure 1 The Spectrum of Isolation Figure 1: The Spectrum of Isolation
Figure 1 shows the spectrum of isolation that may be delivered by a Figure 1 shows the spectrum of isolation that may be delivered by a
network. At one end of the figure, we have traditional statistical network. At one end of the figure, we have traditional statistical
multiplexing technologies that support VPNs. This is a service type multiplexing technologies that support VPNs. This is a service type
that has served the industry well and will continue to do so. At that has served the industry well and will continue to do so. At the
the opposite end of the spectrum, we have the absolute isolation opposite end of the spectrum, we have the absolute isolation provided
provided by dedicated transport networks. The goal of enhanced VPNs by dedicated transport networks. The goal of enhanced VPNs is
is "pragmatic isolation". This is isolation that is better than is "pragmatic isolation". This is isolation that is better than is
obtainable from pure statistical multiplexing, more cost effective obtainable from pure statistical multiplexing, more cost effective
and flexible than a dedicated network, but which is a practical and flexible than a dedicated network, but is a practical solution
solution that is good enough for the majority of applications. that is good enough for the majority of applications. Mechanisms for
Mechanisms for both soft isolation and hard isolation would be both soft isolation and hard isolation would be needed to meet
needed to meet different levels of service requirement. different levels of service requirement.
3.2. Performance Guarantee 3.2. Performance Guarantee
There are several kinds of performance guarantee, including There are several kinds of performance guarantee, including
guaranteed maximum packet loss, guaranteed maximum delay, and guaranteed maximum packet loss, guaranteed maximum delay, and
guaranteed delay variation. Note that these guarantees apply to guaranteed delay variation. Note that these guarantees apply to
conformance traffic, out-of-profile traffic will be handled conformance traffic, out-of-profile traffic will be handled according
according to other requirements. to other requirements.
Guaranteed maximum packet loss is a common parameter, and is usually Guaranteed maximum packet loss is a common parameter, and is usually
addressed by setting packet priorities, queue size, and discard addressed by setting packet priorities, queue size, and discard
policy. However this becomes more difficult when the requirement is policy. However this becomes more difficult when the requirement is
combined with latency requirements. The limiting case is zero combined with latency requirements. The limiting case is zero
congestion loss, and that is the goal of the Deterministic congestion loss, and that is the goal of the Deterministic Networking
Networking work that the IETF [DETNET] and IEEE [TSN] are pursuing. work that the IETF [DETNET] and IEEE [TSN] are pursuing. In modern
In modern optical networks, loss due to transmission errors already optical networks, loss due to transmission errors already approaches
approaches zero, but there are the possibilities of failure of the zero, but there are the possibilities of failure of the interface or
interface or the fiber itself. This can only be addressed by some the fiber itself. This can only be addressed by some form of signal
form of signal duplication and transmission over diverse paths. duplication and transmission over diverse paths.
Guaranteed maximum latency is required in a number of applications Guaranteed maximum latency is required in a number of applications
particularly real-time control applications and some types of particularly real-time control applications and some types of virtual
virtual reality applications. The work of the IETF Deterministic reality applications. The work of the IETF Deterministic Networking
Networking (DetNet) Working Group [DETNET] is relevant; however (DetNet) Working Group [DETNET] is relevant, however additional
additional methods of enhancing the underlay to better support the methods of enhancing the underlay to better support the delay
delay guarantees may be needed, and these methods will need to be guarantees may be needed, and these methods will need to be
integrated with the overall service provisioning mechanisms. integrated with the overall service provisioning mechanisms.
Guaranteed maximum delay variation is a service that may also be Guaranteed maximum delay variation is a service that may also be
needed. [RFC8578] calls up a number of cases where this is needed, needed. [RFC8578] calls up a number of cases where this is needed,
for example in electrical utilities. Time transfer is one example of for example in electrical utilities. Time transfer is one example of
a service that needs this, although it is in the nature of time that a service that needs this, although it is in the nature of time that
the service might be delivered by the underlay as a shared service the service might be delivered by the underlay as a shared service
and not provided through different enhanced VPNs. Alternatively a and not provided through different enhanced VPNs. Alternatively a
dedicated enhanced VPN may be used to provide this as a shared dedicated enhanced VPN may be used to provide this as a shared
service. service.
This suggests that a spectrum of service guarantee be considered This suggests that a spectrum of service guarantee be considered when
when deploying an enhanced VPN. As a guide to understanding the deploying an enhanced VPN. As a guide to understanding the design
design requirements we can consider four types: requirements we can consider four types:
o Best effort
o Assured bandwidth o Best effort
o Guaranteed latency o Assured bandwidth
o Enhanced delivery o Guaranteed latency
o Enhanced delivery
Best effort service is the basic service that current VPNs provide. Best effort service is the basic service that current VPNs can
provide.
An assured bandwidth service is one in which the bandwidth over some An assured bandwidth service is one in which the bandwidth over some
period of time is assured. This can be achieved either simply based period of time is assured. This can be achieved either simply based
on best effort with over-capacity provisioning, or it can be based on best effort with over-capacity provisioning, or it can be based on
on TE-LSPs with bandwidth reservation. The instantaneous bandwidth TE-LSPs with bandwidth reservation. The instantaneous bandwidth is
is however, not necessarily assured, depending on the technique used. however, not necessarily assured, depending on the technique used.
Providing assured bandwidth to VPNs, for example by using per-VPN Providing assured bandwidth to VPNs, for example by using per-VPN TE-
TE-LSPs, is not widely deployed at least partially due to LSPs, is not widely deployed at least partially due to scalability
scalability concerns. concerns. VPN+ aims to provide a more scalable approach for such
kind of service.
Guaranteed latency and enhanced delivery are not yet integrated with
VPNs. A guaranteed latency service has a latency upper bound
provided by the network. Assuring the upper bound is sometimes more
important than minimizing latency.
There are several new technologies that provide some assistance with
performance guarantee. Firstly there is the IEEE project on Time
Sensitive Networking [TSN] which introduces the concept of packet
scheduling of delay and loss sensitive packets. Then the DetNet work
is also of greater relevance in assuring upper bound of end-to-end
packet latency. Flex Ethernet [FLEXE] is also useful to provide
these guarantees.
An enhanced delivery service is one in which the underlay network A guaranteed latency service has a latency upper bound provided by
(at Layer 3) attempts to deliver the packet through multiple paths the network. Assuring the upper bound is sometimes more important
in the hope of eliminating packet loss due to equipment or media than minimizing latency. There are several new technologies that
failures. provide some assistance with performance guarantee. Firstly there is
the IEEE project on Time Sensitive Networking [TSN] which introduces
the concept of packet scheduling of delay and loss sensitive packets.
Then the DetNet work is also of greater relevance in assuring upper
bound of end-to-end packet latency. Flex Ethernet [FLEXE] is also
useful to provide these guarantees. The usage of such underlying
technologies for VPN+ service needs to be considered.
It is these last two characteristics (guaranteed upper bound to An enhanced delivery service is one in which the underlay network (at
latency and elimination of packet loss) that an enhanced VPN adds to Layer 3) attempts to deliver the packet through multiple paths in the
a VPN service. hope of eliminating packet loss due to equipment or media failures.
Such mechanism may need to be used for VPN+ service.
3.3. Integration 3.3. Integration
The only way to achieve the enhanced characteristics provided by an The only way to achieve the enhanced characteristics provided by an
enhanced VPN (such as guaranteed or predicted performance) is by enhanced VPN (such as guaranteed or predicted performance) is by
integrating the overlay VPN with a particular set of network integrating the overlay VPN with a particular set of network
resources in the underlay network which are allocated to meet the resources in the underlay network which are allocated to meet the
service requirement. This needs be done in a flexible and scalable service requirement. This needs be done in a flexible and scalable
way so that it can be widely deployed in operator networks to way so that it can be widely deployed in operator networks to support
support a reasonable number of enhanced VPN customers. a reasonable number of enhanced VPN customers.
Taking mobile networks and in particular 5G into consideration, the Taking mobile networks and in particular 5G into consideration, the
integration of network and the service functions is a likely integration of network and the service functions is a likely
requirement. The work in IETF SFC working group [SFC] provides a requirement. The work in IETF SFC working group [SFC] provides a
foundation for this integration. foundation for this integration.
3.3.1. Abstraction 3.3.1. Abstraction
Integration of the overlay VPN and the underlay network resources Integration of the overlay VPN and the underlay network resources
does not need to be a tight mapping. As described in [RFC7926], does not need to be a tight mapping. As described in [RFC7926],
abstraction is the process of applying policy to a set of abstraction is the process of applying policy to a set of information
information about a TE network to produce selective information that about a TE network to produce selective information that represents
represents the potential ability to connect across the network. The the potential ability to connect across the network. The process of
process of abstraction presents the connectivity graph in a way that abstraction presents the connectivity graph in a way that is
is independent of the underlying network technologies, capabilities, independent of the underlying network technologies, capabilities, and
and topology so that the graph can be used to plan and deliver topology so that the graph can be used to plan and deliver network
network services in a uniform way. services in a uniform way.
Virtual networks can be built on top of an abstracted topology that Virtual networks can be built on top of an abstracted topology that
represents the connectivity capabilities of the underlay network as represents the connectivity capabilities of the underlay network as
described in the framework for Abstraction and Control of TE Networks described in the framework for Abstraction and Control of TE Networks
(ACTN) [RFC8453] as discussed further in Section 5.5. (ACTN) [RFC8453] as discussed further in Section 5.5.
3.4. Dynamic Management 3.4. Dynamic Management
Enhanced VPNs need to be created, modified, and removed from the Enhanced VPNs need to be created, modified, and removed from the
network according to service demand. An enhanced VPN that requires network according to service demand. An enhanced VPN that requires
hard isolation (section 3.1) must not be disrupted by the hard isolation (Section 3.1) must not be disrupted by the
instantiation or modification of another enhanced VPN. Determining instantiation or modification of another enhanced VPN. Determining
whether modification of an enhanced VPN can be disruptive to that whether modification of an enhanced VPN can be disruptive to that
VPN, and in particular whether the traffic in flight will be VPN, and in particular whether the traffic in flight will be
disrupted can be a difficult problem. disrupted can be a difficult problem.
The data plane aspects of this problem are discussed further in The data plane aspects of this problem are discussed further in
Sections 5.1, 5.2, and 5.3. Sections Section 5.1,Section 5.2 and Section 5.3.
The control plane aspects of this problem are discussed further in The control plane aspects of this problem are discussed further in
Section 5.4. Section 5.4.
The management plane aspects of this problem are discussed further The management plane aspects of this problem are discussed further in
in Section 5.5. Section 5.5.
Dynamic changes both to the VPN and to the underlay transport Dynamic changes both to the VPN and to the underlay transport network
network need to be managed to avoid disruption to services that are need to be managed to avoid disruption to services that are sensitive
sensitive to the change of network performance. to the change of network performance.
In addition to non-disruptively managing the network as a result of In addition to non-disruptively managing the network as a result of
gross change such as the inclusion of a new VPN endpoint or a change gross change such as the inclusion of a new VPN endpoint or a change
to a link, VPN traffic might need to be moved as a result of traffic to a link, VPN traffic might need to be moved as a result of traffic
volume changes. volume changes.
3.5. Customized Control 3.5. Customized Control
In some cases it is desirable that an enhanced VPN has a customized In some cases it is desirable that an enhanced VPN has a customized
control plane, so that the tenant of the enhanced VPN can have some control plane, so that the tenant of the enhanced VPN can have some
control of how the resources and functions allocated to this control of how the resources and functions allocated to this enhanced
enhanced VPN are used. For example, the tenant may be able to VPN are used. For example, the tenant may be able to specify the
specify the service paths in his own enhanced VPN. Depending on the service paths in his own enhanced VPN. Depending on the requirement,
requirement, an enhanced VPN may have its own dedicated controller, an enhanced VPN may have its own dedicated controller, which may be
which may be provided with an interface to the control system provided with an interface to the control system provided by the
provided by the network operator. Note that such control is within network operator. Note that such control is within the scope of the
the scope of the tenant's enhanced VPN, any change beyond that would tenant's enhanced VPN, any change beyond that would require some
require some intervention of the operator. intervention of the operator.
A description of the control plane aspects of this problem are A description of the control plane aspects of this problem are
discussed further in Section 5.4. A description of the management discussed further in Section 5.4. A description of the management
plane aspects of this feature can be found in Section 5.5. plane aspects of this feature can be found in Section 5.5.
3.6. Applicability 3.6. Applicability
The technologies described in this document should be applicable to The technologies described in this document should be applicable to a
a number of types of VPN services such as: number types of VPN overlay services such as:
o Layer 2 point-to-point services such as pseudowires [RFC3985] o Layer 2 point-to-point services such as pseudowires [RFC3985]
o Layer 2 VPNs [RFC4664] o Layer 2 VPNs [RFC4664]
o Ethernet VPNs [RFC7209] o Ethernet VPNs [RFC7209]
o Layer 3 VPNs [RFC4364], [RFC2764] o Layer 3 VPNs [RFC4364], [RFC2764]
Where such VPN types need enhanced isolation and delivery Where such VPN types need enhanced isolation and delivery
characteristics, the technologies described in section 5 can be used characteristics, the technologies described in Section 5 can be used
to provide an underlay with the required enhanced performance. to provide an underlay with the required enhanced performance.
3.7. Inter-Domain and Inter-Layer Network 3.7. Inter-Domain and Inter-Layer Network
In some scenarios, an enhanced VPN services may span multiple In some scenarios, an enhanced VPN services may span multiple network
network domains. A domain is considered to be any collection of domains. A domain is considered to be any collection of network
network elements within a common realm of address space or path elements within a common realm of address space or path computation
computation responsibility [RFC5151]. In some domains the operator responsibility [RFC5151]. In some domains the operator may manage a
may manage a multi-layered network, for example, a packet network multi-layered network, for example, a packet network over an optical
over an optical network. When enhanced VPNs are provisioned in such network. When enhanced VPNs are provisioned in such network
network scenarios, the technologies used in different network planes scenarios, the technologies used in different network planes (data
(data plane, control plane, and management plane) need to provide plane, control plane, and management plane) need to provide
mechanisms to support multi-domain and multi-layer coordination and mechanisms to support multi-domain and multi-layer coordination and
integration, so as to provide the required service characteristics integration, so as to provide the required service characteristics
for different enhanced VPNs, and improve network efficiency and for different enhanced VPNs, and improve network efficiency and
operational simplicity. operational simplicity.
4. Architecture of Enhanced VPN 4. Architecture of Enhanced VPN
A number of enhanced VPN services will typically be provided by a A number of enhanced VPN services will typically be provided by a
common network infrastructure. Each enhanced VPN consists of both common network infrastructure. Each enhanced VPN consists of both
the overlay and a corresponding VTN with a specific set of network the overlay and a corresponding VTN with a specific set of network
resources and functions allocated in the underlay to satisfy the resources and functions allocated in the underlay to satisfy the
needs of the VPN tenant. The integration between overlay and needs of the VPN tenant. The integration between overlay and various
various underlay resources ensures the required isolation between underlay resources ensures the required isolation between different
different enhanced VPNs, and achieves the guaranteed performance for enhanced VPNs, and achieves the guaranteed performance for different
different services. services.
An enhanced VPN needs to be designed with consideration given to: An enhanced VPN needs to be designed with consideration given to:
o An enhanced data plane o A enhanced data plane
o A control plane to create enhanced VPNs, making use of the
data plane isolation and performance guarantee techniques
o A management plane for enhanced VPN service life-cycle o A control plane to create enhanced VPNs, making use of the data
management. plane isolation and performance guarantee techniques.
o A management plane for enhanced VPN service life-cycle management.
These required characteristics are expanded below: These required characteristics are expanded below:
o Enhanced data plane o Enhanced data plane
* Provides the required resource isolation capability, e.g. * Provides the required resource isolation capability, e.g.
bandwidth guarantee. bandwidth guarantee.
* Provides the required packet latency and jitter * Provides the required packet latency and jitter
characteristics. characteristics.
* Provides the required packet loss characteristics. * Provides the required packet loss characteristics.
* Provides the mechanism to associate a packet with the set * Provides the mechanism to associate a packet with the set of
of resources allocated to the enhanced VPN which the packet belongs. resources allocated to the enhanced VPN which the packet
belongs.
o Control plane o Control plane
* Collect information about the underlying network topology * Collect information about the underlying network topology and
and resources available and export this to nodes in the network resources available and export this to nodes in the network
and/or the centralized controller as required. and/or the centralized controller as required.
* Create the required virtual transport networks (VTNs) with * Create the required virtual transport networks (VTNs) with the
the resource and properties needed by the enhanced VPN services that resource and properties needed by the enhanced VPN services
are assigned to them. that are assigned to them.
* Determine the risk of SLA violation and take appropriate * Determine the risk of SLA violation and take appropriate
avoiding action. avoiding action.
* Determine the right balance of per-packet and per-node * Determine the right balance of per-packet and per-node state
state according to the needs of enhanced VPN service to scale to the according to the needs of enhanced VPN service to scale to the
required size. required size.
o Management plane o Management plane
* Provides an interface between the enhanced VPN provider * Provides an interface between the enhanced VPN provider (e.g.
(e.g., the Transport Network Manager) and the enhanced VPN clients the Transport Network (TN) Manager) and the enhanced VPN
(e.g., the 3GPP Management System) such that some of the operation clients (e.g. the 3GPP Management System) such that some of the
requests can be met without interfering with the enhanced VPN of operation requests can be met without interfering with the
other clients. enhanced VPN of other clients.
* Provides an interface between the enhanced VPN provider and * Provides an interface between the enhanced VPN provider and the
the enhanced VPN clients to expose transport network capability enhanced VPN clients to expose transport network capability
information toward the enhanced VPN client. information toward the enhanced VPN client.
* Provides the service life-cycle management and operation of * Provides the service life-cycle management and operation of
enhanced VPN (e.g. creation, modification, assurance/monitoring and enhanced VPN (e.g. creation, modification, assurance/monitoring
decommissioning). and decommissioning).
o Operations, Administration, and Maintenance (OAM) o Operations, Administration, and Maintenance (OAM)
* Provides the OAM tools to verify the connectivity and * Provides the OAM tools to verify the connectivity and
performance of the enhanced VPN. performance of the enhanced VPN.
* Provide the OAM tools to verify whether the underlay * Provide the OAM tools to verify whether the underlay network
network resources are correctly allocated and operated properly. resources are correctly allocated and operated properly.
o Telemetry o Telemetry
* Provides the mechanism to collect data plane, control plane, * Provides the mechanism to collect the data plane, control plane
and management plane information about the network. More and management plane data of the network, more specifically:
specifically:
+ Provides the mechanism to collect network data from the *
underlay network for overall performance evaluation and the enhanced
VPN service planning.
+ Provides the mechanism to collect network data about + Provides the mechanism to collect network data from the
each enhanced VPN for monitoring and analytics of the underlay network for overall performance evaluation and the
characteristics and SLA fulfilment of enhanced VPN services. enhanced VPN service planning.
4.1. Layered Architecture + Provides the mechanism to collect network data of each
enhanced VPN for the monitoring and analytics of the
characteristics and SLA fulfilment of enhanced VPN services.
4.1. Layered Architecture
The layered architecture of an enhanced VPN is shown in Figure 2. The layered architecture of an enhanced VPN is shown in Figure 2.
Underpinning everything is the physical network infrastructure layer Underpinning everything is the physical network infrastructure layer
which provide the underlying resources used to provision the which provide the underlying resources used to provision the
separated virtual transport networks (VTNs). This includes the separated virtual transport networks (VTNs). This includes the
partitioning of link and/or node resources. Each subset of link or partitioning of link and/or node resources. Each subset of link or
node resource can be considered as a virtual link or virtual node node resource can be considered as a virtual link or virtual node
used to build the VTNs. used to build the VTNs.
A A
| | | |
+-------------------+ Centralized +-------------------+ Centralized
| Network Controller| Control& Management | Network Controller| Control & Management
+-------------------+ +-------------------+
|| ||
\/ \/
o---------------------------o
/-------------o
o____________/______________o VPN Services
...... (P2P,P2MP,MP2MP...)
o-----------\ /-------------o
o____________X______________o
__________________________ __________________________
/ o----o----o / / o----o----o /
/ / / / VTN-1 / / / / VTN-1
/ o-----o-----o----o----o / / o-----o-----o----o----o /
/_________________________/ /_________________________/
__________________________ __________________________
/ o----o / / o----o /
/ / / \ / VTN-2 / / / \ / VTN-2
/ o-----o----o----o-----o / / o-----o----o----o-----o /
/_________________________/ /_________________________/
...... ... ...... ...
___________________________ ___________________________
/ o----o / / o----o /
/ / / / VTN-3 / / / / VTN-3
/ o-----o----o----o-----o / / o-----o----o----o-----o /
/__________________________/ /__________________________/
++++ ++++ ++++ ++++ ++++ ++++
+--+===+--+===+--+ +--+===+--+===+--+
+--+===+--+===+--+ +--+===+--+===+--+
++++ +++\\ ++++ Physical ++++ +++\\ ++++ Physical
|| || \\ || || || \\ ||
|| || \\ || Network || || \\ || Network
++++ ++++ ++++ \\+++ ++++ ++++ ++++ ++++ \\+++ ++++
+--+===+--+===+--+===+--+===+--+ Infrastructure +--+===+--+===+--+===+--+===+--+ Infrastructure
+--+===+--+===+--+===+--+===+--+ +--+===+--+===+--+===+--+===+--+
++++ ++++ ++++ ++++ ++++ ++++ ++++ ++++ ++++ ++++
O Virtual Node O Virtual Node
-- Virtual Link -- Virtual Link
++++ ++++
+--+ Physical Node with resource partition +--+ Physical Node with resource partition
+--+ +--+
++++ ++++
== Physical Link with resource partition
Figure 2 The Layered Architecture == Physical Link with resource partition
Figure 2: The Layered Architecture of VPN+
Various components and techniques discussed in Section 5 can be used Various components and techniques discussed in Section 5 can be used
to enable resource partition, such as FlexE, Time Sensitive to enable resource partition, such as FlexE, Time Sensitive
Networking, Deterministic Networking, Dedicated queues, etc. These Networking, Deterministic Networking, Dedicated queues, etc. These
partitions may be physical, or virtual so long as the SLA required partitions may be physical, or virtual so long as the SLA required by
by the higher layers is met. the higher layers is met.
Based on the network resources provided by the physical network Based on the network resources provided by the physical network
infrastructure, multiple VTNs can be provisioned, each with infrastructure, multiple VTNs can be provisioned, each with
customized topology and other attributes to meet the requirement of customized topology and other attributes to meet the requirement of
different enhanced VPNs or different groups of enhanced VPNs. To get different enhanced VPNs or different groups of enhanced VPNs. To get
the required characteristic, each VTN needs to be mapped to a set of the required characteristic, each VTN needs to be mapped to a set of
network nodes and links in the network infrastructure. And on each network nodes and links in the network infrastructure. And on each
node or link, the VTN is associated with a set of resources which node or link, the VTN is associated with a set of resources which are
are allocated for the processing of traffic in the VTN. VTN provides allocated for the processing of traffic in the VTN. VTN provides the
the integration between the virtual network topology and the integration between the virtual network topology and the required
required underlying network resources. underlying network resources.
The centralized controller is used to create the VTN, and to The centralized controller is used to create the VTN, and to instruct
instruct the network nodes to allocate the required resources to the network nodes to allocate the required resources to each VTN and
each VTN and to provision the enhanced VPN services on the VTNs. A to provision the enhanced VPN services on the VTNs. A distributed
distributed control plane may also be used for the distribution of control plane may also be used for the distribution of the VTN
the VTN topology and attribute information between nodes within the topology and attribute information between nodes within the VTNs.
VTNs.
The process used to create VTNs and to allocate network resources The process used to create VTNs and to allocate network resources for
for use by VTNs needs to take a holistic view of the needs of all of use by VTNs needs to take a holistic view of the needs of all of its
its tenants (i.e., of all customers and their associated VTNs), and tenants (i.e., of all customers and their associated VTNs), and to
to partition the resources accordingly. However, within a VTN these partition the resources accordingly. However, within a VTN these
resources can, if required, be managed via a dynamic control plane. resources can, if required, be managed via a dynamic control plane.
This provides the required scalability and isolation. This provides the required scalability and isolation.
4.2. Multi-Point to Multi-Point (MP2MP) Connectivity 4.2. Multi-Point to Multi-Point (MP2MP) Connectivity
At the VPN service level, the required connectivity is usually mesh At the VPN service level, the required connectivity is usually mesh
or partial-mesh. To support such kinds of VPN service, the or partial-mesh. To support such kinds of VPN service, the
corresponding VTN in underlay is also an abstract MP2MP medium. corresponding VTN in underlay is also an abstract MP2MP medium.
Other service requirements may be expressed at different granularity, Other service requirements may be expressed at different granularity,
some of which can be applicable to the whole service, while some some of which can be applicable to the whole service, while some
others may be only applicable to some pairs of end points. For others may be only applicable to some pairs of end points. For
example, when particular level of performance guarantee is example, when particular level of performance guarantee is required,
required, the point-to-point path through the underlay of the the point-to-point path through the underlay of the enhanced VPN may
enhanced VPN may need to be specifically engineered to meet the need to be specifically engineered to meet the required performance
required performance guarantee. guarantee.
4.3. Application Specific Network Types 4.3. Application Specific Network Types
Although a lot of the traffic that will be carried over the enhanced Although a lot of the traffic that will be carried over the enhanced
VPN will likely be IPv4 or IPv6, the design has to be capable of VPN will likely be IPv4 or IPv6, the design has to be capable of
carrying other traffic types, in particular Ethernet traffic. This carrying other traffic types, in particular Ethernet traffic. This
is easily accomplished through the various pseudowire (PW) is easily accomplished through the various pseudowire (PW) techniques
techniques [RFC3985]. Where the underlay is MPLS, Ethernet can be [RFC3985]. Where the underlay is MPLS, Ethernet can be carried over
carried over the enhanced VPN encapsulated according to the method the enhanced VPN encapsulated according to the method specified in
specified in [RFC4448]. Where the underlay is IP, Layer Two [RFC4448]. Where the underlay is IP, Layer Two Tunneling Protocol -
Tunneling Protocol - Version 3 (L2TPv3) [RFC3931] can be used with Version 3 (L2TPv3) [RFC3931] can be used with Ethernet traffic
Ethernet traffic carried according to [RFC4719]. Encapsulations carried according to [RFC4719]. Encapsulations have been defined for
have been defined for most of the common Layer 2 types for both PW most of the common Layer 2 types for both PW over MPLS and for
over MPLS and for L2TPv3. L2TPv3.
4.4. Scaling Considerations 4.4. Scaling Considerations
VPNs are instantiated as overlays on top of an operator's network VPNs are instantiated as overlays on top of an operator's network and
and offered as services to the operator's customers. An important offered as services to the operator's customers. An important
feature of overlays is that they are able to deliver services feature of overlays is that they are able to deliver services without
without placing per-service state in the core of the underlay placing per-service state in the core of the underlay network.
network.
Enhanced VPNs may need to install some additional state within the Enhanced VPNs may need to install some additional state within the
network to achieve the additional features that they require. network to achieve the additional features that they require.
Solutions must consider minimizing and controlling the scale of such Solutions must consider minimizing and controlling the scale of such
state, and deployment architectures should constrain the number of state, and deployment architectures should constrain the number of
enhanced VPNs that would exist where such services would place enhanced VPNs that would exist where such services would place
additional state in the network. It is expected that the number of additional state in the network. It is expected that the number of
enhanced VPN would be small in the beginning, and even in future the enhanced VPN would be small in the beginning, and even in future the
number of enhanced VPN will be much fewer than traditional VPNs, number of enhanced VPN will be much fewer than traditional VPNs,
because pre-existing VPN techniques are be good enough to meet the because pre-existing VPN techniques are be good enough to meet the
needs of most existing VPN-type services. needs of most existing VPN-type services.
In general, it is not required that the state in the network be In general, it is not required that the state in the network be
maintained in a 1:1 relationship with the VPN+ services. It will maintained in a 1:1 relationship with the VPN+ services. It will
usually be possible to aggregate a set of VPN+ services so that they usually be possible to aggregate a set of VPN+ services so that they
share the same VTN and the same set of network resources (much in share the same VTN and the same set of network resources (much in the
the way that current VPNs are aggregated over transport tunnels) so way that current VPNs are aggregated over transport tunnels) so that
that collections of enhanced VPNs that require the same behaviour collections of enhanced VPNs that require the same behaviour from the
from the network in terms of resource reservation, latency bounds, network in terms of resource reservation, latency bounds, resiliency,
resiliency, etc. are able to be grouped together. This is an etc. are able to be grouped together. This is an important feature
important feature to assist with the scaling characteristics of VPN+ to assist with the scaling characteristics of VPN+ deployments.
deployments.
See Section 6 for a further discussion of scalability considerations. See Section 6 for a greater discussion of scalability considerations.
5. Candidate Technologies 5. Candidate Technologies
A VPN is a network created by applying a demultiplexing technique to A VPN is a network created by applying a demultiplexing technique to
the underlying network (the underlay) in order to distinguish the the underlying network (the underlay) in order to distinguish the
traffic of one VPN from that of another. A VPN path that travels by traffic of one VPN from that of another. A VPN path that travels by
other than the shortest path through the underlay normally requires other than the shortest path through the underlay normally requires
state in the underlay to specify that path. State is normally state in the underlay to specify that path. State is normally
applied to the underlay through the use of the RSVP signaling applied to the underlay through the use of the RSVP signaling
protocol, or directly through the use of an SDN controller, although protocol, or directly through the use of an SDN controller, although
other techniques may emerge as this problem is studied. This state other techniques may emerge as this problem is studied. This state
gets harder to manage as the number of VPN paths increases. gets harder to manage as the number of VPN paths increases.
Furthermore, as we increase the coupling between the underlay and Furthermore, as we increase the coupling between the underlay and the
the overlay to support the enhanced VPN service, this state will overlay to support the enhanced VPN service, this state will increase
increase further. further.
In an enhanced VPN different subsets of the underlay resources can In an enhanced VPN different subsets of the underlay resources can be
be dedicated to different enhanced VPNs or different groups of dedicated to different enhanced VPNs or different groups of enhanced
enhanced VPNs. An enhanced VPN solution thus needs tighter coupling VPNs. An enhanced VPN solution thus needs tighter coupling with
with underlay than is the case with existing VPNs. We cannot, for underlay than is the case with existing VPNs. We cannot, for
example, share the network resource between enhanced VPNs which example, share the network resource between enhanced VPNs which
require hard isolation. require hard isolation.
5.1. Layer-Two Data Plane 5.1. Layer-Two Data Plane
A number of candidate Layer 2 packet or frame-based data plane A number of candidate Layer 2 packet or frame-based data plane
solutions which can be used provide the required isolation and solutions which can be used provide the required isolation and
guarantees are described in following sections. guarantees are described in following sections.
5.1.1. Flexible Ethernet 5.1.1. Flexible Ethernet
FlexE [FLEXE] provides the ability to multiplex channels over an FlexE [FLEXE] provides the ability to multiplex channels over an
Ethernet link to create point-to-point fixed-bandwidth connections Ethernet link to create point-to-point fixed-bandwidth connections in
in a way that provides hard isolation. FlexE also supports bonding a way that provides hard isolation. FlexE also supports bonding
links to create larger links out of multiple low capacity links. links to create larger links out of multiple low capacity links.
However, FlexE is only a link level technology. When packets are However, FlexE is only a link level technology. When packets are
received by the downstream node, they need to be processed in a way received by the downstream node, they need to be processed in a way
that preserves that isolation in the downstream node. This in turn that preserves that isolation in the downstream node. This in turn
requires a queuing and forwarding implementation that preserves the requires a queuing and forwarding implementation that preserves the
end-to-end isolation. end-to-end isolation.
If different FlexE channels are used for different services, then no If different FlexE channels are used for different services, then no
sharing is possible between the FlexE channels. This means that it sharing is possible between the FlexE channels. This means that it
may be difficult to dynamically redistribute unused bandwidth to may be difficult to dynamically redistribute unused bandwidth to
lower priority services in another FlexE channel. If one FlexE lower priority services in another FlexE channel. If one FlexE
channel is used by one tenant, the tenant can use some methods to channel is used by one tenant, the tenant can use some methods to
manage the relative priority of his own traffic in the FlexE channel. manage the relative priority of his own traffic in the FlexE channel.
5.1.2. Dedicated Queues 5.1.2. Dedicated Queues
DiffServ based queuing systems are described in [RFC2475] and DiffServ based queuing systems are described in [RFC2475] and
[RFC4594]. This is considered insufficient to provide isolation for [RFC4594]. This is considered insufficient to provide isolation for
enhanced VPNs because DiffServ does not always provide enough enhanced VPNs because DiffServ does not always provide enough markers
markers to differentiate between traffic of many enhanced VPNs, or to differentiate between traffic of many enhanced VPNs, or offer the
offer the range of service classes that each VPN needs to provide to range of service classes that each VPN needs to provide to its
its tenants. This problem is particularly acute with an MPLS tenants. This problem is particularly acute with an MPLS underlay,
underlay, because MPLS only provides eight Traffic Classes. because MPLS only provides eight Traffic Classes.
In addition, DiffServ, as currently implemented, mainly provides In addition, DiffServ, as currently implemented, mainly provides per-
per-hop priority-based scheduling, and it is difficult to use it to hop priority-based scheduling, and it is difficult to use it to
achieve quantitive resource reservation. achieve quantitive resource reservation.
In order to address these problems and to reduce the potential In order to address these problems and to reduce the potential
interference between enhanced VPNs, it would be necessary to steer interference between enhanced VPNs, it would be necessary to steer
traffic to dedicated input and output queues per enhanced VPN: some traffic to dedicated input and output queues per enhanced VPN: some
routers have a large number of queues and sophisticated queuing routers have a large number of queues and sophisticated queuing
systems, which could support this, while some routers may struggle systems, which could support this, while some routers may struggle to
to provide the granularity and level of isolation required by the provide the granularity and level of isolation required by the
applications of enhanced VPN. applications of enhanced VPN.
5.1.3. Time Sensitive Networking 5.1.3. Time Sensitive Networking
Time Sensitive Networking (TSN) [TSN] is an IEEE project that is Time Sensitive Networking (TSN) [TSN] is an IEEE project that is
designing a method of carrying time sensitive information over designing a method of carrying time sensitive information over
Ethernet. It introduces the concept of packet scheduling where a Ethernet. It introduces the concept of packet scheduling where a
packet stream may be given a time slot guaranteeing that it packet stream may be given a time slot guaranteeing that it
experiences no queuing delay or increase in latency. The mechanisms experiences no queuing delay or increase in latency. The mechanisms
defined in TSN can be used to meet the requirements of time defined in TSN can be used to meet the requirements of time sensitive
sensitive services of an enhanced VPN. services of an enhanced VPN.
Ethernet can be emulated over a Layer 3 network using an IP or MPLS Ethernet can be emulated over a Layer 3 network using an IP or MPLS
pseudowire. However, a TSN Ethernet payload would be opaque to the pseudowire. However, a TSN Ethernet payload would be opaque to the
underlay and thus not treated specifically as time sensitive data. underlay and thus not treated specifically as time sensitive data.
The preferred method of carrying TSN over a Layer 3 network is The preferred method of carrying TSN over a Layer 3 network is
through the use of deterministic networking as explained in Section through the use of deterministic networking as explained in
5.2.1. Section 5.2.1.
5.2. Layer-Three Data Plane 5.2. Layer-Three Data Plane
We now consider the problem of slice differentiation and resource We now consider the problem of slice differentiation and resource
representation in the network layer. representation in the network layer.
5.2.1. Deterministic Networking 5.2.1. Deterministic Networking
Deterministic Networking (DetNet) [RFC8655] is a technique being Deterministic Networking (DetNet) [RFC8655] is a technique being
developed in the IETF to enhance the ability of Layer 3 networks to developed in the IETF to enhance the ability of Layer 3 networks to
deliver packets more reliably and with greater control over the deliver packets more reliably and with greater control over the
delay. The design cannot use re-transmission techniques such as TCP delay. The design cannot use re-transmission techniques such as TCP
since that can exceed the delay tolerated by the applications. Even since that can exceed the delay tolerated by the applications. Even
the delay improvements that are achieved with Stream Control the delay improvements that are achieved with Stream Control
Transmission Protocol Partial Reliability Extension (SCTP-PR) Transmission Protocol Partial Reliability Extension (SCTP-PR)
[RFC3758] do not meet the bounds set by application demands. DetNet [RFC3758] may not meet the bounds set by application demands. DetNet
pre-emptively sends copies of the packet over various paths to pre-emptively sends copies of the packet over various paths to
minimize the chance of all copies of a packet being lost. It also minimize the chance of all copies of a packet being lost. It also
seeks to set an upper bound on latency, but the goal is not to seeks to set an upper bound on latency, but the goal is not to
minimize latency. minimize latency.
5.2.2. MPLS Traffic Engineering (MPLS-TE) 5.2.2. MPLS Traffic Engineering (MPLS-TE)
MPLS-TE [RFC2702] [RFC3209] introduces the concept of reserving end- MPLS-TE [RFC2702][RFC3209] introduces the concept of reserving end-
to-end bandwidth for a TE-LSP, which can be used to provide point- to-end bandwidth for a TE-LSP, which can be used to provide point-
to-point Virtual Transport Path (VTP) across the underlay network to to-point Virtual Transport Path (VTP) across the underlay network to
support VPNs. VPN traffic can be carried over dedicated TE-LSPs to support VPNs. VPN traffic can be carried over dedicated TE-LSPs to
provide reserved bandwidth for each specific connection in a VPN, provide reserved bandwidth for each specific connection in a VPN, and
and VPNs with similar behaviour requirements may be multiplexed onto VPNs with similar behaviour requirements may be multiplexed onto the
the same TE-LSPs. Some network operators have concerns about the same TE-LSPs. Some network operators have concerns about the
scalability and management overhead of MPLS-TE system, and this has scalability and management overhead of MPLS-TE system, and this has
lead them to consider other solutions for their networks. lead them to consider other solutions for their networks.
5.2.3. Segment Routing 5.2.3. Segment Routing
Segment Routing (SR) [RFC8402] is a method that prepends Segment Routing (SR) [RFC8402] is a method that prepends instructions
instructions to packets at the head-end of a path. These to packets at the head-end of a path. These instructions are used to
instructions are used to specify the nodes and links to be traversed specify the nodes and links to be traversed and allow the packets to
and allow the packets to be routed on paths other than the shortest be routed on paths other than the shortest path. By encoding the
path. By encoding the state in the packet, per-path state is state in the packet, per-path state is transitioned out of the
transitioned out of the network. network.
An SR traffic engineered path operates with a granularity of a link An SR traffic engineered path operates with a granularity of a link
with hints about priority provided through the use of the traffic with hints about priority provided through the use of the traffic
class (TC) or Differentiated Services Code Point (DSCP) field in the class (TC) or Differentiated Services Code Point (DSCP) field in the
header. However to achieve the latency and isolation header. However to achieve the latency and isolation characteristics
characteristics that are sought by the enhanced VPN users, steering that are sought by the enhanced VPN users, steering packets through
packets through specific queues and resources will likely be specific queues and resources will likely be required. With SR, it
required. With SR, it is possible to introduce such fine-grained is possible to introduce such fine-grained packet steering by
packet steering by specifying the queues and resources through an SR specifying the queues and resources through an SR instruction list.
instruction list.
Note that the concept of queue is a useful abstraction for different Note that the concept of queue is a useful abstraction for different
types of underlay mechanism that may be used to provide enhanced types of underlay mechanism that may be used to provide enhanced
isolation and latency support. How the queue satisfies the isolation and latency support. How the queue satisfies the
requirement is implementation specific and is transparent to the requirement is implementation specific and is transparent to the
layer-3 data plane and control plane mechanisms used. layer-3 data plane and control plane mechanisms used.
With Segment Routing, the SR instruction list could be used to build With Segment Routing, the SR instruction list could be used to build
a P2P path, a group of SR SIDs could also be used to represent a MP2MP a P2P path, a group of SR SIDs could also be used to represent a
network. Thus the SR based mechanism could be used to provide both MP2MP network. Thus the SR based mechanism could be used to provide
Virtual Transport Path (VTP) and Virtual Transport Network (VTN) for both Virtual Transport Path (VTP) and Virtual Transport Network (VTN)
enhanced VPN services. for enhanced VPN services.
5.3. Non-Packet Data Plane 5.3. Non-Packet Data Plane
Non-packet underlay data plane technologies often have TE properties Non-packet underlay data plane technologies often have TE properties
and behaviours, and meet many of the key requirements in particular and behaviours, and meet many of the key requirements in particular
for bandwidth guarantees, traffic isolation (with physical isolation for bandwidth guarantees, traffic isolation (with physical isolation
often being an integral part of the technology), highly predictable often being an integral part of the technology), highly predictable
latency and jitter characteristics, measurable loss characteristics, latency and jitter characteristics, measurable loss characteristics,
and ease of identification of flows. The cost is the resources are and ease of identification of flows. The cost is the resources are
allocated on a long term and end-to-end basis. Such an arrangement allocated on a long term and end-to-end basis. Such an arrangement
means that the full cost of the resources has be borne by the means that the full cost of the resources has be borne by the service
service that is allocated with the resources. that is allocated with the resources.
5.4. Control Plane 5.4. Control Plane
Enhanced VPN would likely be based on a hybrid control mechanism, Enhanced VPN would likely be based on a hybrid control mechanism,
which takes advantage of the logically centralized controller for which takes advantage of the logically centralized controller for on-
on-demand provisioning and global optimization, whilst still relying demand provisioning and global optimization, whilst still relying on
on a distributed control plane to provide scalability, high a distributed control plane to provide scalability, high reliability,
reliability, fast reaction, automatic failure recovery, etc. fast reaction, automatic failure recovery, etc. Extension to and
Extension to and optimization of the distributed control plane is optimization of the distributed control plane is needed to support
needed to support the enhanced properties of VPN+. the enhanced properties of VPN+.
RSVP-TE [RFC3209] provides the signaling mechanism for establishing RSVP-TE [RFC3209] provides the signaling mechanism for establishing a
a TE-LSP in an MPLS network with end-to-end resource reservation. TE-LSP in an MPLS network with end-to-end resource reservation. This
This can be seen as a Virtual Transport Path (VTP), which could be can be seen as an approach of providing Virtual Transport Path (VTP),
used to bind the VPN to specific network resources allocated within which could be used to bind the VPN to specific network resources
the underlay, but there remain scalability concerns mentioned in allocated within the underlay, but there remain scalability concerns
Section 5.2.2. mentioned in Section 5.2.2.
The control plane of SR [RFC8665] [RFC8667] [I-D.ietf-idr-bgp-ls- The control plane of SR [RFC8665] [RFC8667]
segment-routing-ext] does not have the capability of signaling [I-D.ietf-idr-bgp-ls-segment-routing-ext] does not have the
resource reservations along the path. On the other hand, the SR capability of signaling resource reservations along the path. On the
approach provides a potential way of binding the underlay network other hand, the SR approach provides a potential way of binding the
resource and the enhanced VPN service without requiring per-path underlay network resource and the enhanced VPN service without
state to be maintained in the network. A centralized controller can requiring per-path state to be maintained in the network. A
perform resource planning and reservation for enhanced VPNs, while centralized controller can perform resource planning and reservation
it needs to ensure that resources are correctly allocated in network for enhanced VPNs, while it needs to ensure that resources are
nodes for the enhanced VPN service. correctly allocated in network nodes for the enhanced VPN service.
The controller could also compute the SR paths based on the planned
or collected network resource and other attributes, and provision the
SR paths based on the mechanism in
[I-D.ietf-spring-segment-routing-policy] to the ingress nodes of the
enhanced VPN services. The distributed control plane may be used to
advertise the network attributes associated with enhanced VPNs, and
compute the SR paths with specific constraints of enhanced VPN
services.
5.5. Management Plane 5.5. Management Plane
The management plane provides the interface between the enhanced VPN The management plane provides the interface between the enhanced VPN
provider and the clients for the service life-cycle management (e.g. provider and the clients for the service life-cycle management (e.g.
creation, modification, assurance/monitoring and decommissioning). creation, modification, assurance/monitoring and decommissioning).
It relies on a set of service data models for the description of the It relies on a set of service data models for the description of the
information and operations needed on the interface. information and operations needed on the interface.
In the context of 5G end-to-end network slicing [TS28530], the As an example, in the context of 5G end-to-end network slicing
management of enhanced VPNs is considered as the management of the [TS28530], the management of enhanced VPNs is considered as the
transport network part of the end-to-end network slice. 3GPP management of the transport network part of the end-to-end network
management system may provide the connectivity and performance slice. 3GPP management system may provide the connectivity and
related parameters as requirements to the management plane of the performance related parameters as requirements to the management
transport network. It may also require the transport network to plane of the transport network. It may also require the transport
expose the capability and status of the transport network slice. network to expose the capability and status of the transport network
Thus, an interface between the enhanced VPN management plane and the slice. Thus, an interface between the enhanced VPN management plane
3GPP network slice management system, and relevant service data and the 3GPP network slice management system, and relevant service
models are needed for the coordination of end-to-end network slice data models are needed for the coordination of end-to-end network
management. slice management.
The management plane interface and data models for enhanced VPN can The management plane interface and data models for enhanced VPN can
be based on the service models described in Section 5.6. be based on the service models described in Section 5.6
5.6. Applicability of Service Data Models to Enhanced VPN 5.6. Applicability of Service Data Models to Enhanced VPN
ACTN supports operators in viewing and controlling different domains ACTN supports operators in viewing and controlling different domains
and presenting virtualized networks to their customers. The ACTN and presenting virtualized networks to their customers. The ACTN
framework [RFC8453] highlights how: framework [RFC8453] highlights how:
o Abstraction of the underlying network resources is provided to o Abstraction of the underlying network resources is provided to
higher-layer applications and customers. higher-layer applications and customers.
o Underlying resources are virtualized allocating those resources o Underlying resources are virtualized and allocated for the
for the customer, application, or service. customer, application, or service.
o A virtualized environment is created allowing operators to view o A virtualized environment is created allowing operators to view
and control multi-domain networks as a single virtualized network. and control multi-domain networks as a single virtualized network.
o Networks can be presented to customers as a virtual network via o Networks can be presented to customers as a virtual network via
open and programmable interfaces. open and programmable interfaces.
The type of network virtualization enabled by ACTN managed The type of network virtualization enabled by ACTN managed
infrastructure provides customers and applications (tenants) with infrastructure provides customers and applications (tenants) with the
the capability to utilize and independently control allocated capability to utilize and independently control allocated virtual
virtual network resources as if they were physically their own network resources as if they were physically their own resources.
resources. Service Data models are used to represent, monitor, and Service Data models are used to represent, monitor, and manage the
manage the virtual networks and services enabled by ACTN. The virtual networks and services enabled by ACTN. The Customer VPN
Customer VPN model (e.g. L3SM [RFC8299]) or an ACTN Virtual Network model (e.g. L3SM [RFC8299], L2SM [RFC8466]) or an ACTN Virtual
(VN) [I-D.ietf-teas-actn-vn-yang] model is a customer view of the Network (VN) [I-D.ietf-teas-actn-vn-yang] model is a customer view of
ACTN managed infrastructure, and is presented by the ACTN provider the ACTN managed infrastructure, and is presented by the ACTN
as a set of abstracted services or resources. The L3VPN network provider as a set of abstracted services or resources. The L3VPN
model [I-D.ietf-opsawg-l3sm-l3nm] and the TE tunnel model [I-D.ietf- network model [I-D.ietf-opsawg-l3sm-l3nm] and [I-D.ietf-opsawg-l2nm]
teas-yang-te] provide a network view of the ACTN managed provide a network view of the ACTN managed infrastructure presented
infrastructure presented by the ACTN provider as a set of transport by the ACTN provider as a set of transport resources.
resources.
5.6.1. Enhanced VPN Delivery in the ACTN Architecture
ACTN provides VPN connections between multiple sites as requested
via the Customer Network Controller (CNC). The CNC is managed by
the customer themselves, and interacts with the network provider's
Multi-Domain Service Controller (MDSC). The Provisioning Network
Controllers (PNC) are responsible for network resource management,
thus the PNCs are remain entirely under the management of the
network provider and are not visible to the customer so that
management is mostly performed by the network provider, with some
flexibility delegated to the customer-managed CNC.
Figure 3 presents a more general representation of how multiple
enhanced VPNs may be created from the resources of multiple physical
networks using the CNC, MDSC, and PNC components of the ACTN
architecture. Each enhanced VPN is controlled by its own CNC. The
CNCs send requests to the provider's MDSC. The provider manages two
different physical networks each under the control of PNC. The MDSC
asks the PNCs to allocate and provision resources to achieve the
enhanced VPNs. In this figure, one enhanced VPN is constructed
solely from the resources of one of the physical networks, while the
the VPN uses resources from both physical networks.
--------------- ( )
| CNC |---------->( VPN+ )
--------^------ ( )
| _(_________ _)
--------------- ( ) ^
| CNC |----------->( VPN+ ) :
------^-------- ( ) :
| | (___________) :
| | ^ ^ :
Boundary | | : : :
Between ==========|====|===================:====:====:========
Customer & | | : : :
Network Provider | | : : :
v v : : :
--------------- : :....:
| MDSC | : :
--------------- : :
^ ---^------ ...
| ( ) .
v ( Physical ) .
---------------- ( Network ) .
| PNC |<-------->( ) ---^------
---------------- | -------- ( )
| |-- ( Physical )
| PNC |<------------------------->( Network )
--------------- ( )
--------
Figure 3 Generic VPN+ Delivery in the ACTN Architecture
5.6.2. Enhanced VPN Features with Service Data Models
This section discusses how the service data models can fulfil the
enhanced VPN requirements described earlier in this document within
the scope of the ACTN architecture.
5.6.2.1. Isolation Between VPNs
The VN YANG model [I-D.ietf-teas-actn-vn-yang] and the TE-service
mapping model [I-D.ietf-teas-te-service-mapping-yang] fulfil the VPN
isolation requirement by providing the following features for the
VPNs:
o Each VPN is identified with a unique identifier (vpn-id) and
can be mapped to a specific VN. Multiple VPNs may mapped to the
same VN according to service requirements and operator's policy.
o Each VPN is managed and controlled independent of other VPNs.
o Each VPN is instantiated with an isolation requirement
described by the TE-service mapping model [I-D.ietf-teas-te-service-
mapping-yang]. This mapping supports all levels of isolation (hard
isolation with deterministic characteristics, hard isolation, soft
isolation, or no isolation).
5.6.2.2. Guaranteed Performance
Performance objectives of a VPN [RFC8299][RFC8466] are expressed
through a QoS profile including the following properties:
o Rate-limit
o Bandwidth
o Latency
o Jitter
[I-D.ietf-teas-actn-vn-yang] and [I-D.ietf-teas-yang-te-topo] allow
configuration of several TE parameters that may help to meet the VPN
performance objectives as follows:
o Bandwidth
o Objective function (e.g., min cost path, min load path, etc.)
o Metric Types and their threshold:
* TE cost, IGP cost, Hop count, or Unidirectional Delay (e.g.,
can set all path delay <= threshold)
Once these requests are instantiated, the resources are committed
and guaranteed through the life cycle of the VPN.
5.6.2.3. Integration
The L3VPN network model provides mechanism to correlate customer's
VPN and the VPN service related resources (e.g., RT and RD)
allocated in the provider's network.
The VPN/Network performance monitoring model [I-D.www-bess-yang-vpn-
service-pm] provides mechanisms to monitor and manage network
Performance on the topology at different layer or the overlay
topology between VPN sites.
These two models provide mechanisms to correlate the customer's VPN
and the actual TE tunnels instantiated in the provider's network.
Service function integration with network topology (L3 and TE
topology) is in progress in [I-D.ietf-teas-sf-aware-topo-model]
which addresses a number of use-cases that show how TE topology
supports various service functions.
5.6.2.4. Dynamic and Customized Management
The ACTN architecture allows the CNC to interact with the provider's
MDSC. This gives the customer dynamic control of their VPNs.
For example, the ACTN VN model [I-D.ietf-teas-actn-vn-yang] allows
life-cycle management to create, modify, and delete VNs on demand.
Customers may also be allowed more customized control of the VN
topology by provisioning tunnels to connect their endpoints, and
even configuring the paths of those tunnels.
Another example is the L3VPN service model [RFC8299] which allows
VPN lifecycle management such as VPN creation, modification, and
deletion on demand.
5.6.3. 5G Transport Service Delivery via Coordinated Data Modules
The overview of network slice structure as defined in the 3GPP 5GS
is shown in Figure 4. The terms are described in specific 3GPP
documents [TS23501] [TS28530].
<================== E2E-NSI =======================>
: : : : :
: : : : :
<====== RAN-NSSI ======><=TN-NSSI=><====== CN-NSSI ======>VL[APL]
: : : : : : : : :
: : : : : : : : :
RW[NFs ]<=TRN-NSSI=>[NFs ]<=TN-NSSI=>[NFs ]<=TRN-NSSI=>[NFs ]VL[APL]
. . . . . . . . . . . . .. . . . . . . . . . . . . ..
.,----. ,----. ,----.. ,----. .,----. ,----. ,----..
UE--|RAN |---| TN |---|RAN |---| TN |--|CN |--| TN |--|CN |--[APL]
.|NFs | `----' |NFs |. `----' .|NFs | `----' |NFs |.
.`----' `----'. .`----' `----'.
. . . . . . . . . . . . .. . . . . . . . . . . . ..
RW RAN MBH CN DN
*Legends
UE: User Equipment
RAN: Radio Access Network
CN: Core Network
DN: Data Network
TN: Transport Network
MBH: Mobile Backhaul
RW: Radio Wave
NF: Network Function
APL: Application Server
NSI: Network Slice Instance
NSSI: Network Slice Subnet Instance
Figure 4 Overview of Structure of Network Slice in 3GPP 5GS
The L3VPN service model [RFC8299] and TEAS VN model [I-D.ietf-teas- 5.6.1. Network Slice Delivery via Coordinated Service Data Models
actn-vn-yang] can both be used to describe the 5G MBB Transport
Service or connectivity service. The L3VPN service model is used to
describe end-to-end IP connectivity service, while the TEAS VN model
is used to describe TE connectivity service between VPN sites or
between RAN NFs and Core network NFs.
A VN in the TEAS VN model with its support of point-to-point or In order to support network slice service in transport network, a
multipoint-to-multipoint connectivity services can be seen as one Transport Slice (TS) Northbound Interface (NBI) data model may be
example of a network slice. needed for a consumer to express the requirements for transport
slices, which can be technology-agnostic. Then these requirements
may be realized using technology-specific Southbound Interface (SBI).
The TE Service mapping model can be used to map L3VPN service As per [RFC8453] and [I-D.ietf-teas-actn-yang], the CNC-MDSC
requests onto underlying network resource and TE models to get the Interface (CMI) of ACTN is used to convey the virtual network service
TE network provisioned. requirements, which is a generic interface to deliver various TE
based VN services. In the context of network slice northbound
interface, there may be some gaps in L3SM/L2SM or VN model, or the
combination of them. The TS NBI is required to communicate the
connectivity of the transport slice, along with the service level
objective (SLO) parameters and traffic selection rules, and provides
a way to monitor the state of the transport slice. This can be
described in a more abstracted manner, so as to reduce the
association with specific realization technologies of transport
network slice, such as the VPN and TE technologies. The transport
slice model as defined in [I-D.wd-teas-transport-slice-yang] provides
an abstracted and generic approach to meet the transport slice NBI
requirement.
For IP VPN service provisioning, the service parameters in the L3VPN The MDSC-PNC Interface (MPI) models in the ACTN architecture can be
service model [RFC8299] can be decomposed into a set of used for the realization of transport slices, for example, in a TE
configuration parameters described in the L3VPN network model [I- enabled transport network, and may also be used for cross-layer or
D.ietf-opsawg-l3sm-l3nm] which will get the VPN network provisioned. cross-domain implementation of transport slice.
6. Scalability Considerations 6. Scalability Considerations
Enhanced VPN provides performance guaranteed services in packet Enhanced VPN provides performance guaranteed services in packet
networks, but with the potential cost of introducing additional networks, but with the potential cost of introducing additional
states into the network. There are at least three ways that this states into the network. There are at least three ways that this
additional state might be presented in the network: additional state might be presented in the network:
o Introduce the complete state into the packet, as is done in SR. o Introduce the complete state into the packet, as is done in SR.
This allows the controller to specify a detailed series of This allows the controller to specify the detailed series of
forwarding and processing instructions for the packet as it transits forwarding and processing instructions for the packet as it
the network. The cost of this is an increase in the packet header transits the network. The cost of this is an increase in the
size. The cost is also that systems will have capabilities enabled packet header size. The cost is also that systems will have
in case they are called upon by a service. This is a type of latent capabilities enabled in case they are called upon by a service.
state, and increases as we more precisely specify the path and This is a type of latent state, and increases as we more precisely
resources that need to be exclusively available to a VPN. specify the path and resources that need to be exclusively
available to a VPN.
o Introduce the state to the network. This is normally done by o Introduce the state to the network. This is normally done by
creating a path using RSVP-TE, which can be extended to introduce creating a path using RSVP-TE, which can be extended to introduce
any element that needs to be specified along the path, for example any element that needs to be specified along the path, for example
explicitly specifying queuing policy. It is possible to use other explicitly specifying queuing policy. It is possible to use other
methods to introduce path state, such as via a Software Defined methods to introduce path state, such as via a Software Defined
Network (SDN) controller, or possibly by modifying a routing Network (SDN) controller, or possibly by modifying a routing
protocol. With this approach there is state per path, per path protocol. With this approach there is state per path, per path
characteristic that needs to be maintained over its life-cycle. characteristic that needs to be maintained over its life-cycle.
This is more state than is needed using SR, but the packets are This is more state than is needed using SR, but the packets are
shorter. shorter.
o Provide a hybrid approach. One example is based on using o Provide a hybrid approach. One example is based on using binding
binding SIDs [RFC8402] to create path fragments, and bind them SIDs [RFC8402] to create path fragments, and bind them together
together with SR. Dynamic creation of a VPN service path using SR with SR. Dynamic creation of a VPN service path using SR requires
requires less state maintenance in the network core at the expense less state maintenance in the network core at the expense of
of larger packet headers. The packet size can be lower if a form of larger packet headers. The packet size can be lower if a form of
loose source routing is used (using a few nodal SIDs), and it will loose source routing is used (using a few nodal SIDs), and it will
be lower if no specific functions or resources on the routers are be lower if no specific functions or resources on the routers are
specified. specified.
Reducing the state in the network is important to enhanced VPN, as Reducing the state in the network is important to enhanced VPN, as it
it requires the overlay to be more closely integrated with the requires the overlay to be more closely integrated with the underlay
underlay than with traditional VPNs. This tighter coupling would than with traditional VPNs. This tighter coupling would normally
normally mean that more state needed to be created and maintained in mean that more state needed to be created and maintained in the
the network, as the state about fine granularity processing would network, as the state about fine granularity processing would need to
need to be loaded and maintained in the routers. However, a segment be loaded and maintained in the routers. However, a segment routed
routed approach allows much of this state to be spread amongst the approach allows much of this state to be spread amongst the network
network ingress nodes, and transiently carried in the packets as ingress nodes, and transiently carried in the packets as SIDs.
SIDs.
6.1. Maximum Stack Depth of SR 6.1. Maximum Stack Depth of SR
One of the challenges with SR is the stack depth that nodes are able One of the challenges with SR is the stack depth that nodes are able
to impose on packets [RFC8491]. This leads to a difficult balance to impose on packets [RFC8491]. This leads to a difficult balance
between adding state to the network and minimizing stack depth, or between adding state to the network and minimizing stack depth, or
minimizing state and increasing the stack depth. minimizing state and increasing the stack depth.
6.2. RSVP Scalability 6.2. RSVP Scalability
The traditional method of creating a resource allocated path through The traditional method of creating a resource allocated path through
an MPLS network is to use the RSVP protocol. However there have an MPLS network is to use the RSVP protocol. However there have been
been concerns that this requires significant continuous state concerns that this requires significant continuous state maintenance
maintenance in the network. Work to improve the scalability of in the network. Work to improve the scalability of RSVP-TE LSPs in
RSVP-TE LSPs in the control plane can be found in [RFC8370]. the control plane can be found in [RFC8370].
There is also concern at the scalability of the forwarder footprint There is also concern at the scalability of the forwarder footprint
of RSVP as the number of paths through an LSR grows. [RFC8577] of RSVP as the number of paths through an LSR grows. [RFC8577]
proposes to address this by employing SR within a tunnel established proposes to address this by employing SR within a tunnel established
by RSVP-TE. by RSVP-TE.
6.3. SDN Scaling 6.3. SDN Scaling
The centralized approach of SDN requires state to be stored in the The centralized approach of SDN requires state to be stored in the
network, but does not have the overhead of also requiring control network, but does not have the overhead of also requiring control
plane state to be maintained. Each individual network node may need plane state to be maintained. Each individual network node may need
to maintain a communication channel with the SDN controller, but to maintain a communication channel with the SDN controller, but that
that compares favourably with the need for a control plane to compares favourably with the need for a control plane to maintain
maintain communication with all neighbors. communication with all neighbors.
However, SDN may transfer some of the scalability concerns from the However, SDN may transfer some of the scalability concerns from the
network to the centralized controller. In particular, there may be network to the centralized controller. In particular, there may be a
a heavy processing burden at the controller, and a heavy load in the heavy processing burden at the controller, and a heavy load in the
network surrounding the controller. network surrounding the controller.
7. OAM Considerations 7. OAM Considerations
The enhanced VPN OAM design needs to consider the following The enhanced VPN OAM design needs to consider the following
requirements: requirements:
o Instrumentation of the underlay so that the network operator can o Instrumentation of the underlay so that the network operator can
be sure that the resources committed to a tenant are operating be sure that the resources committed to a tenant are operating
correctly and delivering the required performance. correctly and delivering the required performance.
o Instrumentation of the overlay by the tenant. This is likely to o Instrumentation of the overlay by the tenant. This is likely to
be transparent to the network operator and to use existing methods. be transparent to the network operator and to use existing
Particular consideration needs to be given to the need to verify the methods. Particular consideration needs to be given to the need
isolation and the various committed performance characteristics. to verify the isolation and the various committed performance
characteristics.
o Instrumentation of the overlay by the network provider to o Instrumentation of the overlay by the network provider to
proactively demonstrate that the committed performance is being proactively demonstrate that the committed performance is being
delivered. This needs to be done in a non-intrusive manner, delivered. This needs to be done in a non-intrusive manner,
particularly when the tenant is deploying a performance sensitive particularly when the tenant is deploying a performance sensitive
application. application.
o Verification of the conformity of the path to the service o Verification of the conformity of the path to the service
requirement. This may need to be done as part of a commissioning requirement. This may need to be done as part of a commissioning
test. test.
A study of OAM in SR networks has been documented in [RFC8403]. A study of OAM in SR networks has been documented in [RFC8403].
8. Telemetry Considerations 8. Telemetry Considerations
Network visibility is essential for network operation. Network Network visibility is essential for network operation. Network
telemetry has been considered as an ideal means to gain sufficient telemetry has been considered as an ideal means to gain sufficient
network visibility with better flexibility, scalability, accuracy, network visibility with better flexibility, scalability, accuracy,
coverage, and performance than conventional OAM technologies. coverage, and performance than conventional OAM technologies.
As defined in [I-D.ietf-opsawg-ntf], the purpose of Network As defined in [I-D.ietf-opsawg-ntf], Network Telemetry is to acquire
Telemetry is to acquire network data remotely for network monitoring network data remotely for network monitoring and operation. It is a
and operation. It is a general term for a large set of network general term for a large set of network visibility techniques and
visibility techniques and protocols. Network telemetry addresses protocols. Network telemetry addresses the current network operation
the current network operation issues and enables smooth evolution issues and enables smooth evolution toward intent-driven autonomous
toward intent-driven autonomous networks. Telemetry can be applied networks. Telemetry can be applied on the forwarding plane, the
on the forwarding plane, the control plane, and the management plane control plane, and the management plane in a network.
in a network.
How the telemetry mechanisms could be used or extended for the How the telemetry mechanisms could be used or extended for the
enhanced VPN service will be described in a separate document. enhanced VPN service is out of the scope of this document.
9. Enhanced Resiliency 9. Enhanced Resiliency
Each enhanced VPN has a life-cycle, and may need modification during Each enhanced VPN has a life-cycle, and may need modification during
deployment as the needs of its tenant change. Additionally, as the deployment as the needs of its tenant change. Additionally, as the
network as a whole evolves, there may need to be garbage collection network as a whole evolves, there may need to be garbage collection
performed to consolidate resources into usable quanta. performed to consolidate resources into usable quanta.
Systems in which the path is imposed such as SR, or some form of Systems in which the path is imposed such as SR, or some form of
explicit routing tend to do well in these applications, because it explicit routing tend to do well in these applications, because it is
is possible to perform an atomic transition from one path to another. possible to perform an atomic transition from one path to another.
This is a single action by the head-end changes the path without the This is a single action by the head-end changes the path without the
need for coordinated action by the routers along the path. However, need for coordinated action by the routers along the path. However,
implementations and the monitoring protocols need to make sure that implementations and the monitoring protocols need to make sure that
the new path is up and meets the required SLA before traffic is the new path is up and meets the required SLA before traffic is
transitioned to it. It is possible for deadlocks to arise as a transitioned to it. It is possible for deadlocks to arise as a
result of the network becoming fragmented over time, such that it is result of the network becoming fragmented over time, such that it is
impossible to create a new path or to modify an existing path impossible to create a new path or to modify an existing path without
without impacting the SLA of other paths. Resolution of this impacting the SLA of other paths. Resolution of this situation is as
situation is as much a commercial issue as it is a technical issue much a commercial issue as it is a technical issue and is outside the
and is outside the scope of this document. scope of this document.
There are, however, two manifestations of the latency problem that There are, however, two manifestations of the latency problem that
are for further study in any of these approaches: are for further study in any of these approaches:
o The problem of packets overtaking one and other if a path latency o The problem of packets overtaking one and other if a path latency
reduces during a transition. reduces during a transition.
o The problem of transient variation in latency in either direction o The problem of transient variation in latency in either direction
as a path migrates. as a path migrates.
There is also the matter of what happens during failure in the There is also the matter of what happens during failure in the
underlay infrastructure. Fast reroute is one approach, but that underlay infrastructure. Fast reroute is one approach, but that
still produces a transient loss with a normal goal of rectifying still produces a transient loss with a normal goal of rectifying this
this within 50ms [RFC5654]. An alternative is some form of N+1 within 50ms [RFC5654]. An alternative is some form of N+1 delivery
delivery such as has been used for many years to support protection such as has been used for many years to support protection from
from service disruption. This may be taken to a different level service disruption. This may be taken to a different level using the
using the techniques proposed by the IETF deterministic network work techniques proposed by the IETF deterministic network work with
with multiple in-network replication and the culling of later multiple in-network replication and the culling of later packets
packets [RFC8655]. [RFC8655].
In addition to the approach used to protect high priority packets, In addition to the approach used to protect high priority packets,
consideration has to be given to the impact of best effort traffic consideration has to be given to the impact of best effort traffic on
on the high priority packets during a transient. Specifically if a the high priority packets during a transient. Specifically if a
conventional re-convergence process is used there will inevitably be conventional re-convergence process is used there will inevitably be
micro-loops and whilst some form of explicit routing will protect micro-loops and whilst some form of explicit routing will protect the
the high priority traffic, lower priority traffic on best effort high priority traffic, lower priority traffic on best effort shortest
shortest paths will micro-loop without the use of a loop prevention paths will micro-loop without the use of a loop prevention
technology. To provide the highest quality of service to high technology. To provide the highest quality of service to high
priority traffic, either this traffic must be shielded from the priority traffic, either this traffic must be shielded from the
micro-loops, or micro-loops must be prevented. micro-loops, or micro-loops must be prevented.
10. Operational Considerations 10. Operational Considerations
It is likely that enhanced VPN service will be introduced in It is likely that enhanced VPN service will be introduced in networks
networks which already have traditional VPN services deployed. which already have traditional VPN services deployed. Depends on
Depends on service requirement, the tenants or the operator may service requirement, the tenants or the operator may choose to use
choose to use traditional VPN or enhanced VPN to fulfil the service traditional VPN or enhanced VPN to fulfil the service requirement.
requirement. The information and parameters to assist such decision The information and parameters to assist such decision needs to be
needs to be reflected on the management interface between the reflected on the management interface between the tenants and the
tenants and the operator. operator.
11. Security Considerations 11. Security Considerations
All types of virtual network require special consideration to be All types of virtual network require special consideration to be
given to the isolation of traffic belonging to different tenants. given to the isolation of traffic belonging to different tenants.
That is, traffic belonging to one VPN must not be delivered to end That is, traffic belonging to one VPN must not be delivered to end
points outside that VPN. In this regard enhanced VPNs neither points outside that VPN. In this regard enhanced VPNs neither
introduce, no experience a greater security risks than other VPNs. introduce, no experience a greater security risks than other VPNs.
However, in an enhanced Virtual Private Network service the However, in an enhanced Virtual Private Network service the
additional service requirements need to be considered. For example, additional service requirements need to be considered. For example,
if a service requires a specific upper bound to latency then it can if a service requires a specific upper bound to latency then it can
skipping to change at page 33, line 37 skipping to change at page 28, line 21
another tenant, i.e., by introducing bursts of traffic for other another tenant, i.e., by introducing bursts of traffic for other
services. services.
The measures to address these dynamic security risks must be The measures to address these dynamic security risks must be
specified as part to the specific solution are form part of the specified as part to the specific solution are form part of the
isolation requirements of a service. isolation requirements of a service.
While an enhanced VPN service may be sold as offering encryption and While an enhanced VPN service may be sold as offering encryption and
other security features as part of the service, customers would be other security features as part of the service, customers would be
well advised to take responsibility for their own security well advised to take responsibility for their own security
requirements themselves possibly by encrypting traffic before requirements themselves possibly by encrypting traffic before handing
handing it off to the service provider. it off to the service provider.
The privacy of enhanced VPN service customers must be preserved. It The privacy of enhanced VPN service customers must be preserved. It
should not be possible for one customer to discover the existence of should not be possible for one customer to discover the existence of
another customer, nor should the sites that are members of an another customer, nor should the sites that are members of an
enhanced VPN be externally visible. enhanced VPN be externally visible.
12. IANA Considerations 12. IANA Considerations
There are no requested IANA actions. There are no requested IANA actions.
13. Contributors 13. Contributors
Daniel King
Email: daniel@olddog.co.uk
Daniel King Adrian Farrel
Email: daniel@olddog.co.uk Email: adrian@olddog.co.uk
Adrian Farrel Jeff Tansura
Email: adrian@olddog.co.uk Email: jefftant.ietf@gmail.com
Jeff Tansura Zhenbin Li
Email: jefftant.ietf@gmail.com Email: lizhenbin@huawei.com
Qin Wu Qin Wu
Email: bill.wu@huawei.com Email: bill.wu@huawei.com
Daniele Ceccarelli Bo Wu
Email: daniele.ceccarelli@ericsson.com Email: lana.wubo@huawei.com
Mohamed Boucadair Daniele Ceccarelli
Email: mohamed.boucadair@orange.com Email: daniele.ceccarelli@ericsson.com
Sergio Belotti Mohamed Boucadair
Email: sergio.belotti@nokia.com Email: mohamed.boucadair@orange.com
Haomian Zheng Sergio Belotti
Email: zhenghaomian@huawei.com Email: sergio.belotti@nokia.com
Zhenbin Li Haomian Zheng
Email: lizhenbin@huawei.com Email: zhenghaomian@huawei.com
14. Acknowledgments 14. Acknowledgements
The authors would like to thank Charlie Perkins, James N Guichard, The authors would like to thank Charlie Perkins, James N Guichard,
John E Drake and Shunsuke Homma for their review and valuable John E Drake and Shunsuke Homma for their review and valuable
comments. comments.
This work was supported in part by the European Commission funded This work was supported in part by the European Commission funded
H2020-ICT-2016-2 METRO-HAUL project (G.A. 761727). H2020-ICT-2016-2 METRO-HAUL project (G.A. 761727).
15. References 15. References
15.1. Normative References
[I-D.ietf-teas-actn-vn-yang] Lee, Y., Dhody, D., Ceccarelli, D., 15.1. Normative References
Bryskin, I., and B. Yoon, "A Yang Data Model for VN
Operation", draft-ietf-teas-actn-vn-yang-07 (work in
progress), October 2019.
[I-D.ietf-teas-te-service-mapping-yang] Lee, Y., Dhody, D., Fioccola, [RFC2764] Gleeson, B., Lin, A., Heinanen, J., Armitage, G., and A.
G., Wu, Q., Ceccarelli, D., and J. Tantsura, "Traffic Malis, "A Framework for IP Based Virtual Private
Engineering (TE) and Service Mapping Yang Model", draft- Networks", RFC 2764, DOI 10.17487/RFC2764, February 2000,
ietf-teas-te-service-mapping-yang-02 (work in progress), <https://www.rfc-editor.org/info/rfc2764>.
September 2019.
[RFC2764] Gleeson, B., Lin, A., Heinanen, J., Armitage, G., and A. [RFC3985] Bryant, S., Ed. and P. Pate, Ed., "Pseudo Wire Emulation
Malis, "A Framework for IP Based Virtual Private Networks", Edge-to-Edge (PWE3) Architecture", RFC 3985,
RFC 2764, DOI 10.17487/RFC2764, February 2000, DOI 10.17487/RFC3985, March 2005,
<https://www.rfc-editor.org/info/rfc2764>. <https://www.rfc-editor.org/info/rfc3985>.
[RFC3209] Awduche, D., Berger, L., Gan, D., Li, T., Srinivasan, V., [RFC4664] Andersson, L., Ed. and E. Rosen, Ed., "Framework for Layer
and G. Swallow, "RSVP-TE: Extensions to RSVP for LSP 2 Virtual Private Networks (L2VPNs)", RFC 4664,
Tunnels", RFC 3209, DOI 10.17487/RFC3209, December 2001, DOI 10.17487/RFC4664, September 2006,
<https://www.rfc-editor.org/info/rfc3209>. <https://www.rfc-editor.org/info/rfc4664>.
[RFC3985] Bryant, S., Ed. and P. Pate, Ed., "Pseudo Wire Emulation 15.2. Informative References
Edge-to-Edge (PWE3) Architecture", RFC 3985, DOI
10.17487/RFC3985, March 2005, <https://www.rfc-
editor.org/info/rfc3985>.
[RFC4664] Andersson, L., Ed. and E. Rosen, Ed., "Framework for Layer [BBF-SD406]
2 Virtual Private Networks (L2VPNs)", RFC 4664, DOI "BBF SD-406: End-to-End Network Slicing", 2016,
10.17487/RFC4664, September 2006, <https://www.rfc- <https://wiki.broadband-forum.org/display/BBF/SD-406+End-
editor.org/info/rfc4664> to-End+Network+Slicing>.
[RFC8299] Wu, Q., Ed., Litkowski, S., Tomotaki, L., and K. Ogaki, [DETNET] "Deterministic Networking", March ,
"YANG Data Model for L3VPN Service Delivery", RFC 8299, <https://datatracker.ietf.org/wg/detnet/about/>.
DOI 10.17487/RFC8299, January 2018, <https://www.rfc-
editor.org/info/rfc8299>.
[RFC8402] Filsfils, C., Ed., Previdi, S., Ed., Ginsberg, L., [FLEXE] "Flex Ethernet Implementation Agreement", March 2016,
Decraene, B., Litkowski, S., and R. Shakir, "Segment <http://www.oiforum.com/wp-content/uploads/OIF-FLEXE-
Routing Architecture", RFC 8402, DOI 10.17487/RFC8402, 01.0.pdf>.
July 2018, <https://www.rfc-editor.org/info/rfc8402>.
[RFC8453] Ceccarelli, D., Ed. and Y. Lee, Ed., "Framework for [I-D.ietf-idr-bgp-ls-segment-routing-ext]
Abstraction and Control of TE Networks (ACTN)", RFC 8453, Previdi, S., Talaulikar, K., Filsfils, C., Gredler, H.,
DOI 10.17487/RFC8453, August 2018, <https://www.rfc- and M. Chen, "BGP Link-State extensions for Segment
editor.org/info/rfc8453>. Routing", draft-ietf-idr-bgp-ls-segment-routing-ext-16
(work in progress), June 2019.
[RFC8466] Wen, B., Fioccola, G., Ed., Xie, C., and L. Jalil, "A YANG [I-D.ietf-opsawg-l2nm]
Data Model for Layer 2 Virtual Private Network (L2VPN) Barguil, S., Dios, O., Boucadair, M., Munoz, L., Jalil,
Service Delivery", RFC 8466, DOI 10.17487/RFC8466, October L., and J. Ma, "A Layer 2 VPN Network YANG Model", draft-
2018, <https://www.rfc-editor.org/info/rfc8466>. ietf-opsawg-l2nm-00 (work in progress), July 2020.
15.2. Informative References [I-D.ietf-opsawg-l3sm-l3nm]
Barguil, S., Dios, O., Boucadair, M., Munoz, L., and A.
Aguado, "A Layer 3 VPN Network YANG Model", draft-ietf-
opsawg-l3sm-l3nm-03 (work in progress), April 2020.
[BBF-SD406] "BBF SD-406: End-to-End Network Slicing", 2016, [I-D.ietf-opsawg-ntf]
<https://wiki.broadband-forum.org/display/BBF/SD-406+End- Song, H., Qin, F., Martinez-Julia, P., Ciavaglia, L., and
to-End+Network+Slicing>. A. Wang, "Network Telemetry Framework", draft-ietf-opsawg-
ntf-03 (work in progress), April 2020.
[DETNET] "Deterministic Networking", March , [I-D.ietf-spring-segment-routing-policy]
<https://datatracker.ietf.org/wg/detnet/about/>. Filsfils, C., Talaulikar, K., Voyer, D., Bogdanov, A., and
P. Mattes, "Segment Routing Policy Architecture", draft-
ietf-spring-segment-routing-policy-08 (work in progress),
July 2020.
[FLEXE] "Flex Ethernet Implementation Agreement", March 2016, [I-D.ietf-teas-actn-vn-yang]
<https://www.oiforum.com/wp-content/uploads/2019/01/OIF- Lee, Y., Dhody, D., Ceccarelli, D., Bryskin, I., and B.
FLEXE-01.0.pdf>. Yoon, "A Yang Data Model for VN Operation", draft-ietf-
teas-actn-vn-yang-08 (work in progress), March 2020.
[I-D.ietf-idr-bgp-ls-segment-routing-ext] Previdi, S., Talaulikar, [I-D.ietf-teas-actn-yang]
K., Filsfils, C., Gredler, H., and M. Chen, "BGP Link- Lee, Y., Zheng, H., Ceccarelli, D., Yoon, B., Dios, O.,
State extensions for Segment Routing", draft-ietf-idr-bgp- Shin, J., and S. Belotti, "Applicability of YANG models
ls-segment-routing-ext-16 (work in progress), June 2019. for Abstraction and Control of Traffic Engineered
Networks", draft-ietf-teas-actn-yang-05 (work in
progress), February 2020.
[I-D.ietf-opsawg-l3sm-l3nm] Aguado, A., Dios, O., Lopezalvarez, V., [I-D.wd-teas-transport-slice-yang]
daniel.voyer@bell.ca, d., and L. Munoz, "Layer 3 VPN Bo, W., Dhody, D., Han, L., and R. Rokui, "A Yang Data
Network Model", draft-ietf-opsawg-l3sm-l3nm-01, (work in Model for Transport Slice NBI", draft-wd-teas-transport-
progress), November 2019. slice-yang-02 (work in progress), July 2020.
[I-D.ietf-opsawg-ntf] Song, H., Qin, F., Martinez-Julia, P., [NGMN-NS-Concept]
Ciavaglia, L., and A. Wang, "Network Telemetry Framework", "NGMN NS Concept", 2016, <https://www.ngmn.org/fileadmin/u
draft-ietf-opsawg-ntf-02 (work in progress), October 2019. ser_upload/161010_NGMN_Network_Slicing_framework_v1.0.8.pd
f>.
[I-D.ietf-teas-sf-aware-topo-model] Bryskin, I., Liu, X., Lee, Y., [RFC2475] Blake, S., Black, D., Carlson, M., Davies, E., Wang, Z.,
Guichard, J., Contreras, L., Ceccarelli, D., and J. and W. Weiss, "An Architecture for Differentiated
Tantsura, "SF Aware TE Topology YANG Model", draft-ietf- Services", RFC 2475, DOI 10.17487/RFC2475, December 1998,
teas-sf-aware-topo-model-04 (work in progress), November <https://www.rfc-editor.org/info/rfc2475>.
2019.
[I-D.ietf-teas-yang-te] Saad, T., Gandhi, R., Liu, X., Beeram, V., [RFC2702] Awduche, D., Malcolm, J., Agogbua, J., O'Dell, M., and J.
and I. Bryskin, "A YANG Data Model for Traffic Engineering McManus, "Requirements for Traffic Engineering Over MPLS",
Tunnels and Interfaces", draft-ietf-teas-yang-te-22 (work RFC 2702, DOI 10.17487/RFC2702, September 1999,
in progress), November 2019. <https://www.rfc-editor.org/info/rfc2702>.
[I-D.ietf-teas-yang-te-topo] Liu, X., Bryskin, I., Beeram, V., Saad, [RFC3209] Awduche, D., Berger, L., Gan, D., Li, T., Srinivasan, V.,
T., Shah, H., and O. Dios, "YANG Data Model for Traffic and G. Swallow, "RSVP-TE: Extensions to RSVP for LSP
Engineering (TE) Topologies", draft-ietf-teas-yang-te- Tunnels", RFC 3209, DOI 10.17487/RFC3209, December 2001,
topo-22 (work in progress), June 2019. <https://www.rfc-editor.org/info/rfc3209>.
[I-D.www-bess-yang-vpn-service-pm] Wang, Z., Wu, Q., Even, R., Wen, [RFC3758] Stewart, R., Ramalho, M., Xie, Q., Tuexen, M., and P.
B., and C. Liu, "A YANG Model for Network and VPN Service Conrad, "Stream Control Transmission Protocol (SCTP)
Performance Monitoring", draft-www-bess-yang-vpn-service- Partial Reliability Extension", RFC 3758,
pm-04 (work in progress), November 2019. DOI 10.17487/RFC3758, May 2004,
<https://www.rfc-editor.org/info/rfc3758>.
[NGMN-NS-Concept] "NGMN NS Concept", 2016, [RFC3931] Lau, J., Ed., Townsley, M., Ed., and I. Goyret, Ed.,
<https://www.ngmn.org/fileadmin/user_upload/161010_NGMN_Ne "Layer Two Tunneling Protocol - Version 3 (L2TPv3)",
twork_Slicing_framework_v1.0.8.pdf>. RFC 3931, DOI 10.17487/RFC3931, March 2005,
<https://www.rfc-editor.org/info/rfc3931>.
[RFC2475] Blake, S., Black, D., Carlson, M., Davies, E., Wang, Z., [RFC4364] Rosen, E. and Y. Rekhter, "BGP/MPLS IP Virtual Private
and W. Weiss, "An Architecture for Differentiated Networks (VPNs)", RFC 4364, DOI 10.17487/RFC4364, February
Services", RFC 2475, DOI 10.17487/RFC2475, December 1998, 2006, <https://www.rfc-editor.org/info/rfc4364>.
<https://www.rfc-editor.org/info/rfc2475>.
[RFC2992] Hopps, C., "Analysis of an Equal-Cost Multi-Path [RFC4448] Martini, L., Ed., Rosen, E., El-Aawar, N., and G. Heron,
Algorithm", RFC 2992, DOI 10.17487/RFC2992, November 2000, "Encapsulation Methods for Transport of Ethernet over MPLS
<https://www.rfc-editor.org/info/rfc2992>. Networks", RFC 4448, DOI 10.17487/RFC4448, April 2006,
<https://www.rfc-editor.org/info/rfc4448>.
[RFC3758] Stewart, R., Ramalho, M., Xie, Q., Tuexen, M., and P. [RFC4594] Babiarz, J., Chan, K., and F. Baker, "Configuration
Conrad, "Stream Control Transmission Protocol (SCTP) Guidelines for DiffServ Service Classes", RFC 4594,
Partial Reliability Extension", RFC 3758, DOI DOI 10.17487/RFC4594, August 2006,
10.17487/RFC3758, May 2004, <https://www.rfc- <https://www.rfc-editor.org/info/rfc4594>.
editor.org/info/rfc3758>.
[RFC3931] Lau, J., Ed., Townsley, M., Ed., and I. Goyret, Ed., [RFC4719] Aggarwal, R., Ed., Townsley, M., Ed., and M. Dos Santos,
"Layer Two Tunneling Protocol - Version 3 (L2TPv3)", RFC Ed., "Transport of Ethernet Frames over Layer 2 Tunneling
3931, DOI 10.17487/RFC3931, March 2005, <https://www.rfc- Protocol Version 3 (L2TPv3)", RFC 4719,
editor.org/info/rfc3931>. DOI 10.17487/RFC4719, November 2006,
<https://www.rfc-editor.org/info/rfc4719>.
[RFC4364] Rosen, E. and Y. Rekhter, "BGP/MPLS IP Virtual Private [RFC5151] Farrel, A., Ed., Ayyangar, A., and JP. Vasseur, "Inter-
Networks (VPNs)", RFC 4364, DOI 10.17487/RFC4364, February Domain MPLS and GMPLS Traffic Engineering -- Resource
2006, <https://www.rfc-editor.org/info/rfc4364>. Reservation Protocol-Traffic Engineering (RSVP-TE)
Extensions", RFC 5151, DOI 10.17487/RFC5151, February
2008, <https://www.rfc-editor.org/info/rfc5151>.
[RFC4448] Martini, L., Ed., Rosen, E., El-Aawar, N., and G. Heron, [RFC5654] Niven-Jenkins, B., Ed., Brungard, D., Ed., Betts, M., Ed.,
"Encapsulation Methods for Transport of Ethernet over MPLS Sprecher, N., and S. Ueno, "Requirements of an MPLS
Networks", RFC 4448, DOI 10.17487/RFC4448, April 2006, Transport Profile", RFC 5654, DOI 10.17487/RFC5654,
<https://www.rfc-editor.org/info/rfc4448>. September 2009, <https://www.rfc-editor.org/info/rfc5654>.
[RFC4594] Babiarz, J., Chan, K., and F. Baker, "Configuration [RFC7149] Boucadair, M. and C. Jacquenet, "Software-Defined
Guidelines for DiffServ Service Classes", RFC 4594, DOI Networking: A Perspective from within a Service Provider
10.17487/RFC4594, August 2006, <https://www.rfc- Environment", RFC 7149, DOI 10.17487/RFC7149, March 2014,
editor.org/info/rfc4594>. <https://www.rfc-editor.org/info/rfc7149>.
[RFC4719] Aggarwal, R., Ed., Townsley, M., Ed., and M. Dos Santos, [RFC7209] Sajassi, A., Aggarwal, R., Uttaro, J., Bitar, N.,
Ed., "Transport of Ethernet Frames over Layer 2 Tunneling Henderickx, W., and A. Isaac, "Requirements for Ethernet
Protocol Version 3 (L2TPv3)", RFC 4719, DOI VPN (EVPN)", RFC 7209, DOI 10.17487/RFC7209, May 2014,
10.17487/RFC4719, November 2006, <https://www.rfc- <https://www.rfc-editor.org/info/rfc7209>.
editor.org/info/rfc4719>.
[RFC5151] Farrel, A., Ed., Ayyangar, A., and JP. Vasseur, "Inter- [RFC7926] Farrel, A., Ed., Drake, J., Bitar, N., Swallow, G.,
Domain MPLS and GMPLS Traffic Engineering - Resource Ceccarelli, D., and X. Zhang, "Problem Statement and
Reservation Protocol-Traffic Engineering (RSVP-TE) Architecture for Information Exchange between
Extensions", RFC 5151, DOI 10.17487/RFC5151, February 2008, Interconnected Traffic-Engineered Networks", BCP 206,
<https://www.rfc-editor.org/info/rfc5151>. RFC 7926, DOI 10.17487/RFC7926, July 2016,
<https://www.rfc-editor.org/info/rfc7926>.
[RFC5654] Niven-Jenkins, B., Ed., Brungard, D., Ed., Betts, M., Ed., [RFC8172] Morton, A., "Considerations for Benchmarking Virtual
Sprecher, N., and S. Ueno, "Requirements of an MPLS Network Functions and Their Infrastructure", RFC 8172,
Transport Profile", RFC 5654, DOI 10.17487/RFC5654, DOI 10.17487/RFC8172, July 2017,
September 2009, <https://www.rfc-editor.org/info/rfc5654> <https://www.rfc-editor.org/info/rfc8172>.
[RFC7149] Boucadair, M. and C. Jacquenet, "Software-Defined [RFC8299] Wu, Q., Ed., Litkowski, S., Tomotaki, L., and K. Ogaki,
Networking: A Perspective from within a Service Provider "YANG Data Model for L3VPN Service Delivery", RFC 8299,
Environment", RFC 7149, DOI 10.17487/RFC7149, March 2014, DOI 10.17487/RFC8299, January 2018,
<https://www.rfc-editor.org/info/rfc7149>. <https://www.rfc-editor.org/info/rfc8299>.
[RFC7209] Sajassi, A., Aggarwal, R., Uttaro, J., Bitar, N., [RFC8370] Beeram, V., Ed., Minei, I., Shakir, R., Pacella, D., and
Henderickx, W., and A. Isaac, "Requirements for Ethernet T. Saad, "Techniques to Improve the Scalability of RSVP-TE
VPN (EVPN)", RFC 7209, DOI 10.17487/RFC7209, May 2014, Deployments", RFC 8370, DOI 10.17487/RFC8370, May 2018,
<https://www.rfc-editor.org/info/rfc7209>. <https://www.rfc-editor.org/info/rfc8370>.
[RFC7926] Farrel, A., Ed., Drake, J., Bitar, N., Swallow, G., [RFC8402] Filsfils, C., Ed., Previdi, S., Ed., Ginsberg, L.,
Ceccarelli, D., and X. Zhang, "Problem Statement and Decraene, B., Litkowski, S., and R. Shakir, "Segment
Architecture for Information Exchange between Routing Architecture", RFC 8402, DOI 10.17487/RFC8402,
Interconnected Traffic-Engineered Networks", BCP 206, RFC July 2018, <https://www.rfc-editor.org/info/rfc8402>.
7926, DOI 10.17487/RFC7926, July 2016, <https://www.rfc-
editor.org/info/rfc7926>.
[RFC8172] Morton, A., "Considerations for Benchmarking Virtual [RFC8403] Geib, R., Ed., Filsfils, C., Pignataro, C., Ed., and N.
Network Functions and Their Infrastructure", RFC 8172, DOI Kumar, "A Scalable and Topology-Aware MPLS Data-Plane
10.17487/RFC8172, July 2017, <https://www.rfc- Monitoring System", RFC 8403, DOI 10.17487/RFC8403, July
editor.org/info/rfc8172>. 2018, <https://www.rfc-editor.org/info/rfc8403>.
[RFC8370] Beeram, V., Ed., Minei, I., Shakir, R., Pacella, D., and T. [RFC8453] Ceccarelli, D., Ed. and Y. Lee, Ed., "Framework for
Saad, "Techniques to Improve the Scalability of RSVP-TE Abstraction and Control of TE Networks (ACTN)", RFC 8453,
Deployments", RFC 8370, DOI 10.17487/RFC8370, May 2018, DOI 10.17487/RFC8453, August 2018,
<https://www.rfc-editor.org/info/rfc8370>. <https://www.rfc-editor.org/info/rfc8453>.
[RFC8403] Geib, R., Ed., Filsfils, C., Pignataro, C., Ed., and N. [RFC8466] Wen, B., Fioccola, G., Ed., Xie, C., and L. Jalil, "A YANG
Kumar, "A Scalable and Topology-Aware MPLS Data-Plane Data Model for Layer 2 Virtual Private Network (L2VPN)
Monitoring System", RFC 8403, DOI 10.17487/RFC8403, July Service Delivery", RFC 8466, DOI 10.17487/RFC8466, October
2018, <https://www.rfc-editor.org/info/rfc8403>. 2018, <https://www.rfc-editor.org/info/rfc8466>.
[RFC8491] Tantsura, J., Chunduri, U., Aldrin, S., and L. Ginsberg, [RFC8491] Tantsura, J., Chunduri, U., Aldrin, S., and L. Ginsberg,
"Signaling Maximum SID Depth (MSD) Using IS-IS", RFC 8491, "Signaling Maximum SID Depth (MSD) Using IS-IS", RFC 8491,
DOI 10.17487/RFC8491, November 2018, <https://www.rfc- DOI 10.17487/RFC8491, November 2018,
editor.org/info/rfc8491>. <https://www.rfc-editor.org/info/rfc8491>.
[RFC8568] Bernardos, CJ., Rahman, A., Zuniga, JC., Contreras, LM., [RFC8568] Bernardos, CJ., Rahman, A., Zuniga, JC., Contreras, LM.,
Aranda, P., and P. Lynch, "Network Virtualization Research Aranda, P., and P. Lynch, "Network Virtualization Research
Challenges", RFC 8568, DOI 10.17487/RFC8568, April 2019, Challenges", RFC 8568, DOI 10.17487/RFC8568, April 2019,
<https://www.rfc-editor.org/info/rfc8568>. <https://www.rfc-editor.org/info/rfc8568>.
[RFC8577] Sitaraman, H., Beeram, V., Parikh, T., and T. Saad, [RFC8577] Sitaraman, H., Beeram, V., Parikh, T., and T. Saad,
"Signaling RSVP-TE Tunnels on a Shared MPLS Forwarding "Signaling RSVP-TE Tunnels on a Shared MPLS Forwarding
Plane", RFC 8577, DOI 10.17487/RFC8577, April 2019, Plane", RFC 8577, DOI 10.17487/RFC8577, April 2019,
<https://www.rfc-editor.org/info/rfc8577>. <https://www.rfc-editor.org/info/rfc8577>.
[RFC8578] Grossman, E., Ed., "Deterministic Networking Use Cases", [RFC8578] Grossman, E., Ed., "Deterministic Networking Use Cases",
RFC 8578, DOI 10.17487/RFC8578, May 2019, RFC 8578, DOI 10.17487/RFC8578, May 2019,
<https://www.rfc-editor.org/info/rfc8578>. <https://www.rfc-editor.org/info/rfc8578>.
[RFC8655] Finn, N., Thubert, P., Varga, B., and J. Farkas, [RFC8655] Finn, N., Thubert, P., Varga, B., and J. Farkas,
"Deterministic Networking Architecture", RFC 8655, DOI "Deterministic Networking Architecture", RFC 8655,
10.17487/RFC8655, October 2019, <https://www.rfc- DOI 10.17487/RFC8655, October 2019,
editor.org/info/rfc8655>. <https://www.rfc-editor.org/info/rfc8655>.
[RFC8665] Psenak, P., Previdi, S., Filsfils, C., Gredler, H., Shakir, [RFC8665] Psenak, P., Ed., Previdi, S., Ed., Filsfils, C., Gredler,
R., Henderickx, W., and J. Tantsura, "OSPF Extensions for H., Shakir, R., Henderickx, W., and J. Tantsura, "OSPF
Segment Routing", RFC 8665, DOI 10.17487/RFC8665, December Extensions for Segment Routing", RFC 8665,
2019, <https://www.rfc-editor.org/info/rfc8665>. DOI 10.17487/RFC8665, December 2019,
<https://www.rfc-editor.org/info/rfc8665>.
[RFC8667] Previdi, S., Ginsberg, L., Filsfils, C., Bashandy, A., [RFC8667] Previdi, S., Ed., Ginsberg, L., Ed., Filsfils, C.,
Gredler, H., and B. Decraene, "IS-IS Extensions for Bashandy, A., Gredler, H., and B. Decraene, "IS-IS
Segment Routing", RFC 8667, DOI 10.17487/RFC8667, December Extensions for Segment Routing", RFC 8667,
2019, <https://www.rfc-editor.org/info/rfc8667>. DOI 10.17487/RFC8667, December 2019,
<https://www.rfc-editor.org/info/rfc8667>.
[SFC] "Service Function Chaining", [SFC] "Service Function Chaining", March ,
<https://datatracker.ietf.org/wg/sfc/about>. <https://datatracker.ietf.org/wg/sfc/about>.
[TS23501] "3GPP TS23.501", 2019, [TS23501] "3GPP TS23.501", 2016,
<https://portal.3gpp.org/desktopmodules/Specifications/Spe <https://portal.3gpp.org/desktopmodules/Specifications/
cificationDetails.aspx?specificationId=3144>. SpecificationDetails.aspx?specificationId=3144>.
[TS28530] "3GPP TS28.530", 2019, [TS28530] "3GPP TS28.530", 2016,
<https://portal.3gpp.org/desktopmodules/Specifications/ <https://portal.3gpp.org/desktopmodules/Specifications/
SpecificationDetails.aspx?specificationId=3273>. SpecificationDetails.aspx?specificationId=3273>.
[TSN] "Time-Sensitive Networking", <https://1.ieee802.org/tsn/>. [TSN] "Time-Sensitive Networking", March ,
<https://1.ieee802.org/tsn/>.
Authors' Addresses Authors' Addresses
Jie Dong Jie Dong
Huawei Huawei
Email: jie.dong@huawei.com Email: jie.dong@huawei.com
Stewart Bryant Stewart Bryant
Futurewei Futurewei
skipping to change at page 40, line 34 skipping to change at page 35, line 28
China Mobile China Mobile
Email: lizhenqiang@chinamobile.com Email: lizhenqiang@chinamobile.com
Takuya Miyasaka Takuya Miyasaka
KDDI Corporation KDDI Corporation
Email: ta-miyasaka@kddi.com Email: ta-miyasaka@kddi.com
Young Lee Young Lee
Sung Kyun Kwan University Samsung
Email: younglee.tx@gmail.com Email: younglee.tx@gmail.com
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