rfc9732v1.txt   rfc9732.txt 
skipping to change at line 12 skipping to change at line 12
Internet Engineering Task Force (IETF) J. Dong Internet Engineering Task Force (IETF) J. Dong
Request for Comments: 9732 Huawei Request for Comments: 9732 Huawei
Category: Informational S. Bryant Category: Informational S. Bryant
ISSN: 2070-1721 University of Surrey ISSN: 2070-1721 University of Surrey
Z. Li Z. Li
China Mobile China Mobile
T. Miyasaka T. Miyasaka
KDDI Corporation KDDI Corporation
Y. Lee Y. Lee
Samsung Samsung
January 2025 February 2025
A Framework for Network Resource Partition Based Enhanced Virtual A Framework for NRP-Based Enhanced Virtual Private Networks
Private Networks
Abstract Abstract
This document describes the framework for enhanced Virtual Private This document describes a framework for Enhanced Virtual Private
Networks (VPNs) that are Network Resource Partition (NRP) based in Networks (VPNs) based on Network Resource Partitions (NRPs) in order
order to support the needs of applications with specific traffic to support the needs of applications with specific traffic
performance requirements (e.g., low latency, bounded jitter). An NRP performance requirements (e.g., low latency, bounded jitter). An NRP
represents a subset of network resources and associated policies in represents a subset of network resources and associated policies in
the underlay network. NRP-based enhanced VPNs leverage the VPN and the underlay network. NRP-based enhanced VPNs leverage the VPN and
Traffic Engineering (TE) technologies and add characteristics that Traffic Engineering (TE) technologies and add characteristics that
specific services require beyond those provided by conventional VPNs. specific services require beyond those provided by conventional VPNs.
Typically, an NRP-based enhanced VPN will be used to underpin network Typically, an NRP-based enhanced VPN will be used to underpin network
slicing, but it could also be of use in its own right providing slicing, but it could also be of use in its own right providing
enhanced connectivity services between customer sites. This document enhanced connectivity services between customer sites. This document
also provides an overview of relevant technologies in different also provides an overview of relevant technologies in different
network layers and identifies some areas for potential new work. network layers and identifies some areas for potential new work.
skipping to change at line 88 skipping to change at line 87
3.5. Customized Control 3.5. Customized Control
3.6. Applicability to Overlay Technologies 3.6. Applicability to Overlay Technologies
3.7. Inter-Domain and Inter-Layer Network 3.7. Inter-Domain and Inter-Layer Network
4. The Architecture of NRP-Based Enhanced VPNs 4. The Architecture of NRP-Based Enhanced VPNs
4.1. Layered Architecture 4.1. Layered Architecture
4.2. Connectivity Types 4.2. Connectivity Types
4.3. Application-Specific Data Types 4.3. Application-Specific Data Types
4.4. Scalable Service Mapping 4.4. Scalable Service Mapping
5. Candidate Technologies 5. Candidate Technologies
5.1. Underlay Forwarding Resource Partitioning 5.1. Underlay Forwarding Resource Partitioning
5.1.1. Flexible Ethernet 5.1.1. Flex Ethernet
5.1.2. Dedicated Queues 5.1.2. Dedicated Queues
5.1.3. Time-Sensitive Networking 5.1.3. Time-Sensitive Networking
5.2. Network Layer Encapsulation and Forwarding 5.2. Network Layer Encapsulation and Forwarding
5.2.1. Deterministic Networking (DetNet) 5.2.1. Deterministic Networking (DetNet)
5.2.2. MPLS Traffic Engineering (MPLS-TE) 5.2.2. MPLS Traffic Engineering (MPLS-TE)
5.2.3. Segment Routing 5.2.3. Segment Routing
5.2.4. New Encapsulation Extensions 5.2.4. New Encapsulation Extensions
5.3. Non-Packet Data Plane 5.3. Non-Packet Data Plane
5.4. Control Plane 5.4. Control Plane
5.5. Management Plane 5.5. Management Plane
skipping to change at line 173 skipping to change at line 172
simply use the term "network slice" to refer to this concept. A simply use the term "network slice" to refer to this concept. A
network slice service enables connectivity between a set of Service network slice service enables connectivity between a set of Service
Demarcation Points (SDPs) with specific Service Level Objectives Demarcation Points (SDPs) with specific Service Level Objectives
(SLOs) and Service Level Expectations (SLEs) over a common underlay (SLOs) and Service Level Expectations (SLEs) over a common underlay
network. A network slice can be realized as a logical network network. A network slice can be realized as a logical network
connecting a number of endpoints and is associated with a set of connecting a number of endpoints and is associated with a set of
shared or dedicated network resources that are used to satisfy the shared or dedicated network resources that are used to satisfy the
SLO and SLE requirements. A network slice is considered to be one SLO and SLE requirements. A network slice is considered to be one
target use case of enhanced VPNs. target use case of enhanced VPNs.
[RFC9543] also introduces the concept of Network Resource Partition [RFC9543] also introduces the concept of NRP, which is a subset of
(NRP), which is a subset of the buffer/queuing/scheduling resources the buffer/queuing/scheduling resources and associated policies on
and associated policies on each of a connected set of links in the each of a connected set of links in the underlay network. An NRP can
underlay network. An NRP can be associated with a dedicated or be associated with a dedicated or shared network topology to select
shared network topology to select or specify the set of links and or specify the set of links and nodes involved.
nodes involved.
The requirements of enhanced VPN services cannot simply be met by The requirements of enhanced VPN services cannot simply be met by
overlay networks: enhanced VPN services require tighter coordination overlay networks: enhanced VPN services require tighter coordination
and integration between the overlay and the underlay networks. and integration between the overlay and the underlay networks.
In the overlay network, the VPN has been defined as the network In the overlay network, the VPN has been defined as the network
construct to provide the required connectivity for different services construct to provide the required connectivity for different services
or customers. Multiple VPN flavors can be considered to create that or customers. Multiple VPN flavors can be considered to create that
construct [RFC4026]. In the underlay network, the NRP is used to construct [RFC4026]. In the underlay network, the NRP is used to
represent a subset of the network resources and associated policies represent a subset of the network resources and associated policies
skipping to change at line 220 skipping to change at line 218
enhanced VPN service. enhanced VPN service.
* The design of the data plane for NRP-based enhanced VPNs. * The design of the data plane for NRP-based enhanced VPNs.
* The necessary control and management protocols in both the * The necessary control and management protocols in both the
underlay and the overlay of enhanced VPNs. underlay and the overlay of enhanced VPNs.
* The mechanisms to achieve integration between the overlay network * The mechanisms to achieve integration between the overlay network
and the underlay network. and the underlay network.
* The necessary Operation, Administration, and Management (OAM) * The necessary Operation, Administration, and Maintenance (OAM)
methods to instrument an enhanced VPN to make sure that the methods to instrument an enhanced VPN to make sure that the
required Service Level Agreement (SLA) between the customer and required Service Level Agreement (SLA) between the customer and
the network operator is met and to take any corrective action the network operator is met and to take any corrective action
(such as switching traffic to an alternate path) to avoid SLA (such as switching traffic to an alternate path) to avoid SLA
violation. violation.
One possible layered network structure to achieve these objectives is One possible layered network structure to achieve these objectives is
shown in Section 4.1. shown in Section 4.1.
It is not envisaged that enhanced VPN services will replace It is not envisaged that enhanced VPN services will replace
skipping to change at line 245 skipping to change at line 243
2. Terminology 2. Terminology
In this document, the relationship of the four terms "VPN", "enhanced In this document, the relationship of the four terms "VPN", "enhanced
VPN", "NRP", and "Network Slice" are as follows: VPN", "NRP", and "Network Slice" are as follows:
* A Virtual Private Network (VPN) refers to the overlay network * A Virtual Private Network (VPN) refers to the overlay network
service that provides connectivity between different customer service that provides connectivity between different customer
sites and that maintains traffic separation between different sites and that maintains traffic separation between different
customers. Examples of technologies to provide VPN services are customers. Examples of technologies to provide VPN services are
as follows: IPVPN [RFC2764], L2VPN [RFC4664], L3VPN [RFC4364], and as follows: IPVPN [RFC2764] [RFC4364], L2VPN [RFC4664], and EVPN
EVPN [RFC7432]. [RFC7432].
* An enhanced VPN service is an evolution of the VPN service that * An enhanced VPN service is an evolution of the VPN service that
makes additional service-specific commitments. An NRP-based makes additional service-specific commitments. An NRP-based
enhanced VPN is made by integrating a VPN with a set of network enhanced VPN is made by integrating a VPN with a set of network
resources allocated in the underlay network (i.e., an NRP). resources allocated in the underlay network (i.e., an NRP).
* A Network Resource Partition (NRP), as defined in [RFC9543], is a * An NRP, as defined in [RFC9543], is a subset of the
subset of the buffer/queuing/scheduling resources and associated buffer/queuing/scheduling resources and associated policies on
policies on each of a connected set of links in the underlay each of a connected set of links in the underlay network. An NRP
network. An NRP can be associated with a dedicated or shared can be associated with a dedicated or shared network topology to
network topology to select or specify the set of links and nodes select or specify the set of links and nodes involved. An NRP is
involved. An NRP is designed to meet the network resources and designed to meet the network resources and performance
performance characteristics required by the enhanced VPN services. characteristics required by the enhanced VPN services.
* A network slice service could be delivered by provisioning one or * A network slice service could be delivered by provisioning one or
more NRP-based enhanced VPNs in the network. Other mechanisms for more NRP-based enhanced VPNs in the network. Other mechanisms for
realizing network slices may exist but are not in the scope of realizing network slices may exist but are not in the scope of
this document. this document.
The term "tenant" is used in this document to refer to a customer of The term "tenant" is used in this document to refer to a customer of
the enhanced VPN services. the enhanced VPN services.
The following terms, defined in other documents, are also used in The following terms, defined in other documents, are also used in
skipping to change at line 282 skipping to change at line 280
SLA: Service Level Agreement (see [RFC9543]) SLA: Service Level Agreement (see [RFC9543])
SLO: Service Level Objective (see [RFC9543]) SLO: Service Level Objective (see [RFC9543])
SLE: Service Level Expectation (see [RFC9543]) SLE: Service Level Expectation (see [RFC9543])
ACTN: Abstraction and Control of TE Networks (see [RFC8453]) ACTN: Abstraction and Control of TE Networks (see [RFC8453])
DetNet: Deterministic Networking (see [RFC8655]) DetNet: Deterministic Networking (see [RFC8655])
FlexE: Flexible Ethernet (see [FLEXE]) FlexE: Flex Ethernet (see [FLEXE])
TSN: Time-Sensitive Networking (see [TSN]) TSN: Time-Sensitive Networking (see [TSN])
VN: Virtual Network (see [RFC8453]) VN: Virtual Network (see [RFC8453])
3. Overview of the Requirements 3. Overview of the Requirements
This section provides an overview of the requirements of an enhanced This section provides an overview of the requirements of an enhanced
VPN service. VPN service.
skipping to change at line 310 skipping to change at line 308
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 according conformance traffic; out-of-profile traffic will be handled according
to a separate agreement with the customer (see, for example, to a separate agreement with the customer (see, for example,
Section 3.6 of [RFC7297]). Section 3.6 of [RFC7297]).
Guaranteed maximum packet loss is usually addressed by setting packet Guaranteed maximum packet loss is usually addressed by setting packet
priorities, queue sizes, and discard policies. However, this becomes priorities, queue sizes, and discard policies. However, this becomes
more difficult when the requirement is combined with latency more difficult when the requirement is combined with latency
requirements. The limiting case is zero congestion loss, and that is requirements. The limiting case is zero congestion loss, and that is
the goal of Deterministic Networking (DetNet) [RFC8655] and Time- the goal of DetNet [RFC8655] and Time-Sensitive Networking (TSN)
Sensitive Networking (TSN) [TSN]. In modern optical networks, loss [TSN]. In modern optical networks, loss due to transmission errors
due to transmission errors already approaches zero, but there is the already approaches zero, but there is the possibility of failure of
possibility of failure of the interface or the fiber itself. This the interface or the fiber itself. This type of fault can be
type of fault can be addressed by some form of signal duplication and addressed by some form of signal duplication and transmission over
transmission over diverse paths. diverse paths.
Guaranteed maximum latency is required by a number of applications, Guaranteed maximum latency is required by a number of applications,
particularly real-time control applications and some types of particularly real-time control applications and some types of
augmented reality and virtual reality (AR/VR) applications. DetNet augmented reality and virtual reality (AR/VR) applications. DetNet
techniques may be considered [RFC8655]; however, additional methods techniques may be considered [RFC8655]; however, additional methods
of enhancing the underlay to better support the delay guarantees may of enhancing the underlay to better support the delay guarantees may
be needed. These methods will need to be integrated with the overall be needed. These methods will need to be integrated with the overall
service provisioning mechanisms. service provisioning mechanisms.
Guaranteed maximum delay variation is a performance guarantee that Guaranteed maximum delay variation is a performance guarantee that
skipping to change at line 499 skipping to change at line 497
traffic policing or shaping, prioritizing in using shared network traffic policing or shaping, prioritizing in using shared network
resources, etc., so that a subset of bandwidth, buffers, and queueing resources, etc., so that a subset of bandwidth, buffers, and queueing
resources can be available in the underlay network to support the resources can be available in the underlay network to support the
enhanced VPN services. enhanced VPN services.
To provide the required traffic isolation, or to reduce the To provide the required traffic isolation, or to reduce the
interaction with other enhanced VPN services, network resources may interaction with other enhanced VPN services, network resources may
need to be reserved in the data plane of the underlay network and need to be reserved in the data plane of the underlay network and
dedicated to traffic from a specific enhanced VPN service or a dedicated to traffic from a specific enhanced VPN service or a
specific group of enhanced VPN services. This may introduce specific group of enhanced VPN services. This may introduce
scalability concerns both in the implementation (as each enhanced VPN scalability concerns in the implementation, as each enhanced VPN may
may need to be tracked in the network) and in how many resources need need to be tracked in the network. It may also introduce scalability
to be reserved and how the services are mapped to the resources concerns in deployment, such as how many resources need to be
reserved and how the services are mapped to the resources
(Section 4.4). Thus, some trade-off needs to be considered to (Section 4.4). Thus, some trade-off needs to be considered to
provide the traffic isolation and limited interaction between an provide the traffic isolation and limited interaction between an
enhanced VPN service and other services. enhanced VPN service and other services.
A dedicated physical network can be used to meet stricter SLO and SLE A dedicated physical network can be used to meet stricter SLO and SLE
requests, at the cost of allocating resources on a long-term and end- requests, at the cost of allocating resources on a long-term and end-
to-end basis. On the other hand, where adequate traffic isolation to-end basis. On the other hand, where adequate traffic isolation
and limited interaction can be achieved at the packet layer, this and limited interaction can be achieved at the packet layer, this
permits the resources to be shared amongst a group of services and permits the resources to be shared amongst a group of services and
only dedicated to a service on a temporary basis. By combining only dedicated to a service on a temporary basis. By combining
conventional VPNs with TE/QoS/security techniques, an enhanced VPN conventional VPNs with TE, QoS, and security techniques, an enhanced
offers a variety of means to honor customer's requirements. VPN offers a variety of means to honor customer's requirements.
3.3. Integration with Network Resources and Service Functions 3.3. Integration with Network Resources and Service Functions
The way to achieve the characteristics demand of an enhanced VPN The way to meet the enhanced VPN service's demand for certain
service (such as guaranteed or predictable performance) is by characteristics (such as guaranteed or predictable performance) is by
integrating the overlay VPN with a particular set of resources in the integrating the overlay VPN with a particular set of resources in the
underlay network that are allocated to meet the service requirements. underlay network that are allocated to meet the service requirements.
This needs to be done in a flexible and scalable way so that it can This needs to be done in a flexible and scalable way so that it can
be widely deployed in operators' networks to support a good number of be widely deployed in operators' networks to support a good number of
enhanced VPN services. enhanced VPN services.
Taking mobile networks and, in particular, 5G into consideration, the Taking mobile networks and, in particular, 5G into consideration, the
integration of the network with service functions is likely a integration of the network with service functions is likely a
requirement. The IETF's work on Service Function Chaining (SFC) requirement. The IETF's work on Service Function Chaining (SFC)
[RFC7665] provides a foundation for this. Service functions in the [RFC7665] provides a foundation for this. Service functions in the
skipping to change at line 540 skipping to change at line 539
services, which means the service functions may need to be an services, which means the service functions may need to be an
integral part of the corresponding NRP. The details of the integral part of the corresponding NRP. The details of the
integration between service functions and enhanced VPNs are out of integration between service functions and enhanced VPNs are out of
the scope of this document. the scope of this document.
3.3.1. Abstraction 3.3.1. Abstraction
Integration of the overlay VPN and the underlay network resources and Integration of the overlay VPN and the underlay network resources and
service functions does not always need to be a direct mapping. As service functions does not always need to be a direct mapping. As
described in [RFC7926], abstraction is the process of applying policy described in [RFC7926], abstraction is the process of applying policy
to a set of information about a traffic engineered (TE) network to to a set of information about a traffic-engineered network to produce
produce selective information that represents the potential ability selective information that represents the potential ability to
to connect across the network. The process of abstraction presents connect across the network. The process of abstraction presents the
the connectivity graph in a way that is independent of the underlying connectivity graph in a way that is independent of the underlying
network technologies, capabilities, and topology so that the graph network technologies, capabilities, and topology so that the graph
can be used to plan and deliver network services in a uniform way. can be used to plan and deliver network services in a uniform way.
With the approach of abstraction, an enhanced VPN may be built on top Using the abstraction approach, an enhanced VPN may be built on top
of an abstracted topology that represents the connectivity of an abstracted topology that represents the connectivity
capabilities of the underlay TE-based network as described in the capabilities of the underlay TE-based network as described in the
framework for Abstraction and Control of TE Networks (ACTN) [RFC8453] framework for Abstraction and Control of TE Networks (ACTN) [RFC8453]
as discussed further in Section 5.5. as discussed further in Section 5.5.
3.4. Dynamic Changes 3.4. Dynamic Changes
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 demands (including scheduled requests). network according to service demands (including scheduled requests).
An enhanced VPN that requires limited interaction with other services An enhanced VPN that requires limited interaction with other services
skipping to change at line 574 skipping to change at line 573
Dynamic changes both to the enhanced VPN and to the underlay network Dynamic changes both to the enhanced VPN and to the underlay network
need to be managed to avoid disruption to services that are sensitive need to be managed to avoid disruption to services that are sensitive
to changes in network performance. to changes in network performance.
In addition to managing the network without disruption during changes In addition to managing the network without disruption during changes
such as the inclusion of a new enhanced VPN service endpoint or a such as the inclusion of a new enhanced VPN service endpoint or a
change to a link, enhanced VPN traffic might need to be moved because change to a link, enhanced VPN traffic might need to be moved because
of changes to traffic patterns and volume. This means that during of changes to traffic patterns and volume. This means that during
the lifetime of an enhanced VPN service, closed-loop optimization is the lifetime of an enhanced VPN service, closed-loop optimization is
needed so that the delivered service always matches the ordered needed so that the delivered service always matches the ordered SLA.
service SLA.
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 5.1, 5.2, and 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 in The management plane aspects of this problem are discussed further in
Section 5.5. Section 5.5.
skipping to change at line 711 skipping to change at line 709
- Maps enhanced VPN services to an appropriate NRP. - Maps enhanced VPN services to an appropriate NRP.
- Determines the risk of SLA violation and takes appropriate - Determines the risk of SLA violation and takes appropriate
avoidance/correction actions. avoidance/correction actions.
- Considers the right balance of per-packet and per-node state - Considers the right balance of per-packet and per-node state
according to the needs of the enhanced VPN services to scale to according to the needs of the enhanced VPN services to scale to
the required size. the required size.
* The management plane includes management interfaces, the * The management plane includes management interfaces, the OAM and
Operations, Administration, and Maintenance (OAM) and telemetry telemetry mechanisms. More specifically, it provides:
mechanisms. More specifically, it provides:
- An interface between the enhanced VPN service provider (e.g., - An interface between the enhanced VPN service provider (e.g.,
the operator's network management system) and the enhanced VPN the operator's network management system) and the enhanced VPN
customer (e.g., an organization or service with an enhanced VPN customer (e.g., an organization or service with an enhanced VPN
requirement) such that the operation requests and the related requirement) such that the requests for specific operations and
parameters can be exchanged without the awareness of other the related parameters can be exchanged without the awareness
enhanced VPN customers. of other enhanced VPN customers.
- An interface between the enhanced VPN service provider and the - An interface between the enhanced VPN service provider and the
enhanced VPN customers to expose the network capability enhanced VPN customers to expose the network capability
information toward the customer. information toward the customer.
- The service life-cycle management and operation of enhanced VPN - The service life-cycle management and operation of enhanced VPN
services (e.g., creation, modification, assurance/monitoring, services (e.g., creation, modification, assurance/monitoring,
and decommissioning). and decommissioning).
- The OAM tools to verify whether the underlay network resources - The OAM tools to verify whether the underlay network resources
skipping to change at line 816 skipping to change at line 813
== Physical Link with resource partition == Physical Link with resource partition
Figure 1: The Layered Architecture of Enhanced VPNs Figure 1: The Layered Architecture of Enhanced VPNs
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 partitioning of the physical network to enable resource partitioning of the physical network
infrastructure, such as FlexE, TSN, dedicated queues, etc. These infrastructure, such as FlexE, TSN, dedicated queues, etc. These
partitions may be physical or virtual so long as the SLA required by partitions may be physical or virtual so long as the SLA required by
the higher layers is met. the higher layers is met.
Based on the set of network resource partitions provided by the Based on the set of NRPs provided by the physical network
physical network infrastructure, multiple NRPs can be created. Each infrastructure, multiple NRPs can be created. Each of these NRPs:
of these NRPs:
* has a set of dedicated or shared network resources allocated from * has a set of dedicated or shared network resources allocated from
the physical underlay network, and the physical underlay network,
* can be associated with a customized logical network topology so as * can be associated with a customized logical network topology, and
to meet the requirements of different enhanced VPN services or
* meets the requirements of different enhanced VPN services or
different groups of enhanced VPN services. different groups of enhanced VPN services.
According to the associated logical network topology, each NRP needs According to the associated logical network topology, each NRP needs
to be instantiated on a set of network nodes and links that are to be instantiated on a set of network nodes and links that are
involved in the logical topology. On each node or link, each NRP is involved in the logical topology. On each node or link, each NRP is
associated with a set of local resources that are allocated for the associated with a set of local resources that are allocated for the
processing of traffic in the NRP. The NRP provides the integration processing of traffic in the NRP. The NRP provides the integration
between the logical network topology and the required underlying between the logical network topology and the required underlying
network resources. network resources.
skipping to change at line 928 skipping to change at line 925
[NRP-SCALABILITY] provides more details of scalability considerations [NRP-SCALABILITY] provides more details of scalability considerations
for the NRPs used to instantiate NRPs, and Section 7 includes a for the NRPs used to instantiate NRPs, and Section 7 includes a
greater discussion of scalability considerations. greater discussion of scalability considerations.
5. Candidate Technologies 5. Candidate Technologies
A VPN is created by applying a demultiplexing technique to the A VPN is created by applying a demultiplexing technique to the
underlying network (the underlay) to distinguish the traffic of one underlying network (the underlay) to distinguish the traffic of one
VPN from that of another. The connections of a VPN are supported by VPN from that of another. The connections of a VPN are supported by
a set of underlay paths. A path that travels by other than the a set of underlay paths. Any path other than the shortest path
shortest path through the underlay normally requires state to specify through the underlay normally requires state to specify that path.
that path. The state of the paths could be applied to the underlay The state of the paths could be applied to the underlay through the
through the use of the RSVP-TE signaling protocol or directly through use of the RSVP-TE signaling protocol or directly through the use of
the use of a Software-Defined Networking (SDN) controller. Based on a Software-Defined Networking (SDN) controller. Based on Segment
Segment Routing (SR), state could be maintained at the ingress node Routing (SR), state could be maintained at the ingress node of the
of the path and carried in the data packet. Other techniques may path and carried in the data packet. Other techniques may emerge as
emerge as this problem is studied. This state gets harder to manage this problem is studied. This state gets harder to manage as the
as the number of paths increases. Furthermore, as we increase the number of paths increases. Furthermore, as we increase the coupling
coupling between the underlay and the overlay to support the enhanced between the underlay and the overlay to support the enhanced VPN
VPN service, this state is likely to increase further. Through the service, this state is likely to increase further. Through the use
use of NRP, a subset of underlay network resources can be either of NRP, a subset of underlay network resources can be either
dedicated for a particular enhanced VPN service or shared among a dedicated for a particular enhanced VPN service or shared among a
group of enhanced VPN services. A group of underlay paths can be group of enhanced VPN services. A group of underlay paths can be
established using the common set of network resources of the NRP. established using the common set of network resources of the NRP.
This section describes the candidate technologies and examines them This section describes the candidate technologies and examines them
in the context of the different network planes that may be used in the context of the different network planes that may be used
together to build NRPs. Section 5.1 discusses the L2 packet-based or together to build NRPs. Section 5.1 discusses the L2 packet-based or
frame-based forwarding-plane mechanisms for resource partitioning. frame-based forwarding-plane mechanisms for resource partitioning.
Section 5.2 discusses the corresponding encapsulation and forwarding Section 5.2 discusses the corresponding encapsulation and forwarding
mechanisms in the network layer. Non-packet data plane mechanisms mechanisms in the network layer. Non-packet data plane mechanisms
are briefly discussed in Section 5.3. The control plane and are briefly discussed in Section 5.3. The control plane and
management plane mechanisms are discussed in Sections 5.4 and 5.5, management plane mechanisms are discussed in Sections 5.4 and 5.5,
respectively. respectively.
5.1. Underlay Forwarding Resource Partitioning 5.1. Underlay Forwarding Resource Partitioning
Several candidate L2 packet-based or frame-based forwarding-plane Several candidate L2 packet-based or frame-based forwarding-plane
mechanisms that can provide the required traffic isolation and mechanisms that can provide the required traffic isolation and
performance guarantees are described in the following sections. performance guarantees are described in the following sections.
5.1.1. Flexible Ethernet 5.1.1. Flex 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 in Ethernet link to create point-to-point fixed-bandwidth connections in
a way that provides separation between enhanced VPN services. FlexE a way that provides separation between enhanced VPN services. FlexE
also supports bonding links to create larger links out of multiple also supports bonding multiple low-capacity links to create larger
low-capacity links. 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 traffic isolation in the downstream node. In that preserves traffic isolation. In turn, this requires a queuing
turn, this requires a queuing and forwarding implementation that and forwarding implementation that preserves the end-to-end
preserves the end-to-end separation of enhanced VPNs. separation of enhanced VPNs.
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. Thus, it may be sharing is possible between the FlexE channels. Thus, it may be
difficult to dynamically redistribute unused bandwidth to lower difficult to dynamically redistribute unused bandwidth to lower
priority services in another FlexE channel. If one FlexE channel is priority services in another FlexE channel. If one FlexE channel is
used by one customer, the customer can use some methods to manage the used by one customer, the customer can use some methods to manage the
relative priority of their own traffic in the FlexE channel. relative priority of their own traffic in the FlexE channel.
5.1.2. Dedicated Queues 5.1.2. Dedicated Queues
skipping to change at line 1019 skipping to change at line 1016
packet scheduling where a packet stream may be given a time slot packet scheduling where a packet stream may be given a time slot
guaranteeing that it will experience no queuing delay or increase in guaranteeing that it will experience no queuing delay or increase in
latency beyond a very small scheduling delay. The mechanisms defined latency beyond a very small scheduling delay. The mechanisms defined
in TSN can be used to meet the requirements of time-sensitive traffic in TSN can be used to meet the requirements of time-sensitive traffic
flows of enhanced VPN service. flows of enhanced VPN service.
Ethernet can be emulated over a L3 network using an IP or MPLS Ethernet can be emulated over a L3 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; thus, it would not be treated specifically as time- underlay; thus, it would not be treated specifically as time-
sensitive data. The preferred method of carrying TSN over a L3 sensitive data. The preferred method of carrying TSN over a L3
network is through the use of deterministic networking as explained network is through the use of DetNet as explained in Section 5.2.1.
in Section 5.2.1.
5.2. Network Layer Encapsulation and Forwarding 5.2. Network Layer Encapsulation and Forwarding
This section considers the problem of enhanced VPN service This section considers the problem of enhanced VPN service
differentiation and the representation of underlying network differentiation and the representation of underlying network
resources in the network layer. More specifically, it describes the resources in the network layer. More specifically, it describes the
possible data plane mechanisms to determine the network resources and possible data plane mechanisms to determine the network resources and
the logical network topology or paths associated with an NRP. the logical network topology or paths associated with an NRP.
5.2.1. Deterministic Networking (DetNet) 5.2.1. Deterministic Networking (DetNet)
skipping to change at line 1056 skipping to change at line 1052
MPLS-TE (see [RFC2702] and [RFC3209]) introduces the concept of MPLS-TE (see [RFC2702] and [RFC3209]) introduces the concept of
reserving end-to-end bandwidth for a TE-LSP, which can be used to reserving end-to-end bandwidth for a TE-LSP, which can be used to
provide a set of point-to-point resource-reserved paths across the provide a set of point-to-point resource-reserved paths across the
underlay network to support VPN services. VPN traffic can be carried underlay network to support VPN services. VPN traffic can be carried
over dedicated TE-LSPs to provide guaranteed bandwidth for each over dedicated TE-LSPs to provide guaranteed bandwidth for each
specific connection in a VPN, and VPNs with similar behavior specific connection in a VPN, and VPNs with similar behavior
requirements may be multiplexed onto the same TE-LSPs. Some network requirements may be multiplexed onto the same TE-LSPs. Some network
operators have concerns about the scalability and management overhead operators have concerns about the scalability and management overhead
of MPLS-TE system, especially with regard to those systems that use of MPLS-TE system, especially with regard to those systems that use
an active control plane, and this has lead them to consider other an active control plane, and this has lead them to consider other
solutions for traffic engineering in their networks. solutions for TE in their networks.
5.2.3. Segment Routing 5.2.3. Segment Routing
Segment Routing (SR) [RFC8402] is a method that prepends instructions SR [RFC8402] is a method that prepends instructions to packets at the
to packets at the headend of a path. These instructions are used to headend of a path. These instructions are used to specify the nodes
specify the nodes and links to be traversed, and they allow the and links to be traversed, and they allow the packets to be routed on
packets to be routed on paths other than the shortest path. By paths other than the shortest path. By encoding the state in the
encoding the state in the packet, per-path state is transitioned out packet, per-path state is transitioned out of the network. SR can be
of the network. SR can be instantiated using the MPLS data plane instantiated using the MPLS data plane (SR-MPLS) (see [RFC8660]) or
(SR-MPLS) (see [RFC8660]) or the IPv6 data plane (SRv6) (see the IPv6 data plane (SRv6) (see [RFC8986]).
[RFC8986]).
An SR traffic engineered path operates with the granularity of a An SR traffic-engineered path operates with the granularity of a
link. Hints about priority are provided using the Traffic Class (TC) link. Hints about priority are provided using the Traffic Class (TC)
field in the packet header. However, to achieve the performance and field in the packet header. However, to achieve the performance and
isolation characteristics that are sought by enhanced VPN customers, isolation characteristics that are sought by enhanced VPN customers,
it will be necessary to steer packets through specific virtual links it will be necessary to steer packets through specific virtual links
and/or queues on the same link and direct them to use specific and/or queues on the same link and direct them to use specific
resources. With SR, it is possible to introduce such fine-grained resources. With SR, it is possible to introduce such fine-grained
packet steering by specifying the queues and the associated resources packet steering by specifying the queues and the associated resources
through an SR instruction list. One approach to do this is described through an SR instruction list. One approach to do this is described
in [RESOURCE-AWARE-SEGMENTS]. in [RESOURCE-AWARE-SEGMENTS].
Note that the concept of a queue is a useful abstraction for Note that the concept of a queue is a useful abstraction for
different types of underlay mechanisms that may be used to provide different types of underlay mechanisms that may be used to provide
enhanced isolation and performance support. How the queue satisfies enhanced isolation and performance support. How the queue satisfies
the requirement is implementation specific and is transparent to the the requirement is implementation specific and is transparent to the
L3 data plane and control plane mechanisms used. L3 data plane and control plane mechanisms used.
With Segment Routing, the SR instruction list could be used to build With SR, the SR instruction list could be used to build a P2P SR
a P2P SR path. In addition, a group of SR Segment Identifiers (SIDs) path. In addition, a group of SR Segment Identifiers (SIDs) could
could also be used to represent an MP2MP network. Thus, the SR-based also be used to represent an MP2MP network. Thus, the SR-based
mechanism could be used to provide both resource-reserved paths and mechanism could be used to provide both resource-reserved paths and
NRPs for enhanced VPN services. NRPs for enhanced VPN services.
5.2.4. New Encapsulation Extensions 5.2.4. New Encapsulation Extensions
In contrast to reusing an existing data plane for enhanced VPN, In contrast to reusing an existing data plane for enhanced VPN,
another possible approach is to introduce new encapsulations or another possible approach is to introduce new encapsulations or
extensions to an existing data plane to allow dedicated identifiers extensions to an existing data plane to allow dedicated identifiers
for the underlay network resources of an enhanced VPN and the logical for the underlay network resources of an enhanced VPN and the logical
network topology or paths associated with an enhanced VPN. This may network topology or paths associated with an enhanced VPN. This may
skipping to change at line 1131 skipping to change at line 1126
The cost is that the resources are allocated on a long-term and end- The cost is that the resources are allocated on a long-term and end-
to-end basis. Such an arrangement means that the full cost of the to-end basis. Such an arrangement means that the full cost of the
resources has to be borne by the client to which the resources are resources has to be borne by the client to which the resources are
allocated. When an NRP built with this data plane is used to support allocated. When an NRP built with this data plane is used to support
multiple enhanced VPN services, the cost could be distributed among multiple enhanced VPN services, the cost could be distributed among
such a group of services. such a group of services.
5.4. Control Plane 5.4. Control Plane
The control plane of NRP-based enhanced VPNs is likely to be based on The control plane of NRP-based enhanced VPNs is likely be based on a
a hybrid control mechanism that takes advantage of a logically hybrid control mechanism that takes advantage of a logically
centralized controller for on-demand provisioning and Global centralized controller for on-demand provisioning and global
Concurrent Optimization (GCO) while still relying on a distributed optimization while still relying on a distributed control plane to
control plane to provide scalability, high reliability, fast provide scalability, high reliability, fast reaction, automatic
reaction, automatic failure recovery, etc. Extension to and failure recovery, etc. Extension to and optimization of the
optimization of the centralized and distributed control plane is centralized and distributed control plane is needed to support the
needed to support the enhanced properties of an NRP-based enhanced enhanced properties of an NRP-based enhanced VPN.
VPN.
As described in Section 4, the enhanced VPN control plane needs to As described in Section 4, the enhanced VPN control plane needs to
provide the following functions: provide the following functions:
* Collection of information about the underlying network topology * Collection of information about the underlying network topology
and network resources and exportation of this to network nodes and network resources and exportation of this to network nodes
and/or a centralized controller as required. and/or a centralized controller as required.
* Creation of NRPs with the network resource and topology properties * Creation of NRPs with the network resource and topology properties
needed by NRP-based enhanced VPN services. needed by NRP-based enhanced VPN services.
skipping to change at line 1169 skipping to change at line 1163
Underlying network topology and resource information can be collected Underlying network topology and resource information can be collected
using mechanisms based on the existing IGP and Border Gateway using mechanisms based on the existing IGP and Border Gateway
Protocol - Link State (BGP-LS) [RFC9552]. The creation of NRPs and Protocol - Link State (BGP-LS) [RFC9552]. The creation of NRPs and
the distribution of NRP attributes may need further control protocol the distribution of NRP attributes may need further control protocol
extensions. The computation of service paths based on the attributes extensions. The computation of service paths based on the attributes
and constraints of the NRP can be performed either by the headend and constraints of the NRP can be performed either by the headend
node of the path or by a centralized Path Computation Element (PCE) node of the path or by a centralized Path Computation Element (PCE)
[RFC4655]. [RFC4655].
Two candidate control plane mechanisms for path setup in the NRP are Two candidate control plane mechanisms for path setup in the NRP are
RSVP-TE and Segment Routing (SR). RSVP-TE and SR.
* RSVP-TE, as described in [RFC3209], provides the signaling * RSVP-TE, as described in [RFC3209], provides the signaling
mechanism for establishing a TE-LSP in an MPLS network with end- mechanism for establishing a TE-LSP in an MPLS network with end-
to-end resource reservation. This can be seen as an approach of to-end resource reservation. This can be seen as an approach of
providing resource-reserved paths that could be used to bind the providing resource-reserved paths that could be used to bind the
VPN to a specific set of network resources allocated within the VPN to a specific set of network resources allocated within the
underlay; however, there remain scalability concerns, as mentioned underlay; however, there remain scalability concerns, as mentioned
in Section 5.2.2. in Section 5.2.2.
* The SR control plane, as described in [RFC8665], [RFC8667], and * The SR control plane, as described in [RFC8665], [RFC8667], and
skipping to change at line 1214 skipping to change at line 1208
models for the description of the information and operations needed models for the description of the information and operations needed
on the interface. on the interface.
As an example, in the context of 5G end-to-end network slicing As an example, in the context of 5G end-to-end network slicing
[TS28530], the management of the transport network segment of the 5G [TS28530], the management of the transport network segment of the 5G
end-to-end network slice can be realized with the management plane of end-to-end network slice can be realized with the management plane of
the enhanced VPN. The 3GPP management system may provide the the enhanced VPN. The 3GPP management system may provide the
connectivity and performance-related parameters as requirements to connectivity and performance-related parameters as requirements to
the management plane of the transport network. It may also require the management plane of the transport network. It may also require
the transport network to expose the capabilities and status of the the transport network to expose the capabilities and status of the
network slice. Thus, an interface between the enhanced VPN network slice. Thus, the coordination of 5G end-to-end network slice
management plane and the 5G network slice management system, and management requires an interface between the enhanced VPN management
relevant service data models are needed for the coordination of 5G plane and the 5G network slice management system, and relevant
end-to-end network slice management. service data models.
The management plane interface and data models for enhanced VPN The management plane interface and data models for enhanced VPN
services can be based on the service models described in Section 5.6. services can be based on the service models described in Section 5.6.
It is important that the life-cycle management support in-place It is important that the life-cycle management support in-place
modification of enhanced VPN services. That is, it should be modification of enhanced VPN services. That is, it should be
possible to add and remove endpoints, as well as to change the possible to add and remove endpoints, as well as to change the
requested characteristics of the service that is delivered. The requested characteristics of the service that is delivered. The
management system needs to be able to assess the revised enhanced VPN management system needs to be able to assess the revised enhanced VPN
requests and determine whether they can be provided by the existing requests and determine whether they can be provided by the existing
skipping to change at line 1276 skipping to change at line 1270
progress service data models to enhanced VPNs. [RFC8309] describes progress service data models to enhanced VPNs. [RFC8309] describes
the scope and purpose of service models and shows where a service the scope and purpose of service models and shows where a service
model might fit into an SDN-based network management architecture. model might fit into an SDN-based network management architecture.
New service models may also be introduced for some of the required New service models may also be introduced for some of the required
management functions. management functions.
Service data models are used to represent, monitor, and manage the Service data models are used to represent, monitor, and manage the
virtual networks and services enabled by enhanced VPNs. The VPN virtual networks and services enabled by enhanced VPNs. The VPN
customer service models (e.g., the L3VPN Service Model (L3SM) in customer service models (e.g., the L3VPN Service Model (L3SM) in
[RFC8299], the L2VPN Service Model (L2SM) in [RFC8466]), or the ACTN [RFC8299], the L2VPN Service Model (L2SM) in [RFC8466]), or the ACTN
Virtual Network (VN) model in [RFC9731]) are service models that can VN model in [RFC9731]) are service models that can provide the
provide the customer's view of the enhanced VPN service. The L3VPN customer's view of the enhanced VPN service. The L3VPN Network Model
Network Model (L3NM) from [RFC9182] and the L2VPN Network Model (L3NM) from [RFC9182] and the L2VPN Network Model (L2NM) from
(L2NM) from [RFC9291] provide the operator's view of the managed [RFC9291] provide the operator's view of the managed infrastructure
infrastructure as a set of virtual networks and the associated as a set of virtual networks and the associated resources. The
resources. The Service Attachment Points (SAPs) model in [RFC9408] Service Attachment Points (SAPs) model in [RFC9408] provides an
provides an abstract view of the Service Attachment Points (SAPs) to abstract view of the SAPs to various network services in the provider
various network services in the provider network, where enhanced VPN network, where enhanced VPN could be one of the service types.
could be one of the service types. [RFC9375] provides the data model [RFC9375] provides the data model for performance monitoring of
for performance monitoring of network and VPN services. Augmentation network and VPN services. Augmentation to these service models may
to these service models may be needed to provide the enhanced VPN be needed to provide the enhanced VPN services. The NRP model in
services. The NRP model in [NRP-YANG] further provides the [NRP-YANG] further provides the management of the NRP topology and
management of the NRP topology and resources both in the controller resources both in the controller and in the network devices to
and in the network devices to instantiate the NRPs needed for the instantiate the NRPs needed for the enhanced VPN services.
enhanced VPN services.
6. Applicability in Network Slice Realization 6. Applicability in Network Slice Realization
This section describes the applicability of NRP-based enhanced VPN This section describes the applicability of NRP-based enhanced VPN
for network slice realization. for network slice realization.
In order to provide network slice services to customers, a In order to provide network slice services to customers, a
technology-agnostic network slice service model [NETWORK-SLICE-YANG] technology-agnostic network slice service model [NETWORK-SLICE-YANG]
is needed for the customers to communicate the requirements of is needed for the customers to communicate the requirements of
network slices (SDPs, connectivity, SLOs, and SLEs). These network slices (SDPs, connectivity, SLOs, and SLEs). These
skipping to change at line 1416 skipping to change at line 1409
path. This is more network state than is needed using SR, but the path. This is more network state than is needed using SR, but the
packets are usually shorter. packets are usually shorter.
* by providing a hybrid approach. One example is based on using * by providing a hybrid approach. One example is based on using
binding SIDs (see [RFC8402]) to represent path fragments and binding SIDs (see [RFC8402]) to represent path fragments and
binding them together with SR. Dynamic creation of a VPN service binding them together with SR. Dynamic creation of a VPN service
path using SR requires less state maintenance in the network core path using SR requires less state maintenance in the network core
at the expense of larger packet headers. The packet size can be at the expense of larger packet headers. The packet size can be
lower if a form of loose source routing is used (using a few nodal lower if a form of loose source routing is used (using a few nodal
SIDs), and it will be lower if no specific functions or resources SIDs), and it will be lower if no specific functions or resources
on the routers are specified. For SRv6, the packet size may also on the routers are specified. For Segment Routing over IPv6
be reduced by utilizing the compression techniques specified in (SRv6), the packet size may also be reduced by utilizing the
[SRv6-SRH-COMPRESSION]. compression techniques specified in [SRv6-SRH-COMPRESSION].
Reducing state in the network is important to enhanced VPNs, as it Reducing the state in the network is important to the deployment of
requires the overlay to be more closely integrated with the underlay enhanced VPNs, as they require the overlay to be more closely
than with conventional VPNs. This tighter coupling would normally integrated with the underlay than with conventional VPNs. This
mean that more state needs to be created and maintained in the tighter coupling would normally mean that more state needs to be
network, as state about fine-granularity processing would need to be created and maintained in the network, as state about fine-
loaded and maintained in the routers. Aggregation is a well- granularity processing would need to be loaded and maintained in the
established approach to reduce the amount of state and improve routers. Aggregation is a well-established approach to reduce the
scaling, and NRP is considered to be the network construct to amount of state and improve scaling, and NRP is considered to be the
aggregate the states of enhanced VPN services. In addition, an SR network construct to aggregate the states of enhanced VPN services.
approach allows much of the state to be spread amongst the network In addition, an SR approach allows much of the state to be spread
ingress nodes and transiently carried in the packets as SIDs. amongst the network ingress nodes and transiently carried in the
packets as SIDs.
The following subsections describe some of the scalability concerns The following subsections describe some of the scalability concerns
that need to be considered. Further discussion of the scalability that need to be considered. Further discussion of the scalability
considerations of the underlaying network constructs of NRP-based considerations of the underlaying network constructs of NRP-based
enhanced VPNs can be found in [NRP-SCALABILITY]. enhanced VPNs can be found in [NRP-SCALABILITY].
7.1. Maximum Stack Depth of SR 7.1. 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
skipping to change at line 1461 skipping to change at line 1455
maintenance in the network. Work to improve the scalability of RSVP- maintenance in the network. Work to improve the scalability of RSVP-
TE LSPs in the control plane can be found in [RFC8370]. TE LSPs in 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-TE as the number of paths through a Label Switching Router of RSVP-TE as the number of paths through a Label Switching Router
(LSR) grows. [RFC8577] addresses this by employing SR within a (LSR) grows. [RFC8577] addresses this by employing SR within a
tunnel established by RSVP-TE. tunnel established by RSVP-TE.
7.3. SDN Scaling 7.3. SDN Scaling
The centralized approach of SDN requires control plane state to be The centralized SDN-based approach requires control plane state to be
stored in the network, but can reduce the overhead of control stored in the network, but can reduce the overhead of control
channels to be maintained. Each individual network node may need to channels to be maintained. Each individual network node may need to
maintain a control channel with an SDN controller, which is maintain a control channel with an SDN controller, which is
considered more scalable compared to the need of maintaining control considered more scalable compared to the need of maintaining control
channels with a set of neighbor nodes. channels with a set of neighbor nodes.
However, SDN may transfer some of the scalability concerns from the However, SDN may transfer some of the scalability concerns from the
network to a centralized controller. In particular, there may be a network to a centralized controller. In particular, there may be 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. A centralized controller may network surrounding the controller. A centralized controller may
skipping to change at line 1492 skipping to change at line 1486
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 is explicit routing, tend to do well in these applications because it is
possible to perform an atomic transition from one path to another. possible to perform an atomic transition from one path to another.
That is, a single action by the headend that changes the path without That is, a single action by the headend that changes the path without
the need for coordinated action by the routers along the path. the need for coordinated action by the routers along the path.
However, implementations and the monitoring protocols need to make However, implementations and the monitoring protocols need to make
sure that the new path is operational and meets the required SLA sure that the new path is operational and meets the required SLA
before traffic is transitioned to it. It is possible for deadlocks before traffic is transitioned to it. It is possible for deadlocks
to arise as a result of the network becoming fragmented over time, to arise as a result of the network becoming fragmented over time,
such that it is impossible to create a new path or to modify an such that it is impossible to create a new path or to modify an
existing path without impacting the SLA of other paths. The GCO existing path without impacting the SLA of other paths. The global
mechanisms as described in [RFC5557] and discussed in [RFC7399] may concurrent optimization mechanisms as described in [RFC5557] and
be helpful, while complete resolution of this situation is as much a discussed in [RFC7399] may be helpful, while complete resolution of
commercial issue as it is a technical issue. this situation is as much a commercial issue as it is a technical
issue.
However, there are two manifestations of the latency problem that are However, there are two manifestations of the latency problem that are
for further study in any of these approaches: for further study in any of these approaches:
* Packets overtaking one another if path latency reduces during a * Packets overtaking one another if path latency reduces during a
transition. transition.
* Transient variation in latency in either direction as a path * Transient variation in latency in either direction as a path
migrates. migrates.
skipping to change at line 1537 skipping to change at line 1532
This section describes the considerations about the OAM and telemetry This section describes the considerations about the OAM and telemetry
mechanisms used to support the verification, monitoring, and mechanisms used to support the verification, monitoring, and
optimization of the characteristics and SLA fulfillment of NRP-based optimization of the characteristics and SLA fulfillment of NRP-based
enhanced VPN services. It should be read along with Section 5.5, enhanced VPN services. It should be read along with Section 5.5,
which gives consideration to the management plane techniques that can which gives consideration to the management plane techniques that can
be used to build NRPs. be used to build NRPs.
9.1. OAM Considerations 9.1. OAM Considerations
The design of OAM for enhanced VPN services needs to consider the The following requirements need to be considered in the design of OAM
following requirements: for enhanced VPN services:
* Instrumentation of the NRP (the virtual underlay) so that the * Instrumentation of the NRP (the virtual underlay) so that the
network operator can be sure that the resources committed to a network operator can be sure that the resources committed to a
customer are operating correctly and delivering the required customer are operating correctly and delivering the required
performance. It is important that the OAM packets follow the same performance. It is important that the OAM packets follow the same
path and set of resources as the service packets mapped to the path and set of resources as the service packets mapped to the
NRP. NRP.
* Instrumentation of the overlay by the customer. This is likely to * Instrumentation of the overlay by the customer. This is likely to
be transparent to the network operator and to use existing be transparent to the network operator and to use existing
skipping to change at line 1573 skipping to change at line 1568
telemetry has been considered to be an ideal means to gain sufficient telemetry has been considered to be 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 [RFC9232], the objective of network telemetry is to As defined in [RFC9232], the objective of network telemetry is to
acquire network data remotely for network monitoring and operation. acquire network data remotely for network monitoring and operation.
It is a general term for a large set of network visibility techniques It is a general term for a large set of network visibility techniques
and protocols. Network telemetry addresses the current network and protocols. Network telemetry addresses the current network
operation issues and enables smooth evolution toward intent-driven operation issues and enables smooth evolution toward intent-driven
autonomous networks. Telemetry can be applied on the forwarding autonomous networks. Telemetry can be applied on the forwarding
plane, the control plane, and the management plane in a network. plane, the control plane, and the management plane in a network. The
Telemetry for enhanced VPN service needs to consider the following following requirements need to be considered for telemetry for
requirements: enhanced VPN service:
* Collecting data of NRPs for overall performance evaluation and the * Collecting data of NRPs for overall performance evaluation and the
planning of the enhanced VPN services. planning of the enhanced VPN services.
* Collecting data of each enhanced VPN service for monitoring and * Collecting data of each enhanced VPN service for monitoring and
analytics of the service characteristics and SLA fulfillment. analytics of the service characteristics and SLA fulfillment.
How the telemetry mechanisms could be used or extended for enhanced How the telemetry mechanisms could be used or extended for enhanced
VPN services is out of the scope of this document. VPN services is out of the scope of this document.
skipping to change at line 1675 skipping to change at line 1670
"Carrying Network Resource (NR) related Information in "Carrying Network Resource (NR) related Information in
IPv6 Extension Header", Work in Progress, Internet-Draft, IPv6 Extension Header", Work in Progress, Internet-Draft,
draft-ietf-6man-enhanced-vpn-vtn-id-09, 3 November 2024, draft-ietf-6man-enhanced-vpn-vtn-id-09, 3 November 2024,
<https://datatracker.ietf.org/doc/html/draft-ietf-6man- <https://datatracker.ietf.org/doc/html/draft-ietf-6man-
enhanced-vpn-vtn-id-09>. enhanced-vpn-vtn-id-09>.
[NETWORK-SLICE-YANG] [NETWORK-SLICE-YANG]
Wu, B., Dhody, D., Rokui, R., Saad, T., and J. Mullooly, Wu, B., Dhody, D., Rokui, R., Saad, T., and J. Mullooly,
"A YANG Data Model for the RFC 9543 Network Slice "A YANG Data Model for the RFC 9543 Network Slice
Service", Work in Progress, Internet-Draft, draft-ietf- Service", Work in Progress, Internet-Draft, draft-ietf-
teas-ietf-network-slice-nbi-yang-20, 27 January 2025, teas-ietf-network-slice-nbi-yang-22, 8 February 2025,
<https://datatracker.ietf.org/doc/html/draft-ietf-teas- <https://datatracker.ietf.org/doc/html/draft-ietf-teas-
ietf-network-slice-nbi-yang-20>. ietf-network-slice-nbi-yang-22>.
[NGMN-NS-Concept] [NGMN-NS-Concept]
hao ,, "NGMN NS Concept", <https://www.ngmn.org/fileadmin/ NGMN Alliance, "NGMN 5G P1 Requirements and Architecture
user_upload/161010_NGMN_Network_Slicing_framework_v1.0.8.p Work Stream End-to-End Architecture: Description of
df>. Network Slicing Concept", Version 1.0.8 (draft), 14
September 2016, <https://www.ngmn.org/wp-content/uploads/P
ublications/2016/161010_NGMN_Network_Slicing_framework_v1.
0.8.pdf>.
[NRP-SCALABILITY] [NRP-SCALABILITY]
Dong, J., Li, Z., Gong, L., Yang, G., and G. S. Mishra, Dong, J., Li, Z., Gong, L., Yang, G., and G. S. Mishra,
"Scalability Considerations for Network Resource "Scalability Considerations for Network Resource
Partition", Work in Progress, Internet-Draft, draft-ietf- Partition", Work in Progress, Internet-Draft, draft-ietf-
teas-nrp-scalability-06, 21 October 2024, teas-nrp-scalability-06, 21 October 2024,
<https://datatracker.ietf.org/doc/html/draft-ietf-teas- <https://datatracker.ietf.org/doc/html/draft-ietf-teas-
nrp-scalability-06>. nrp-scalability-06>.
[NRP-YANG] Wu, B., Dhody, D., Beeram, V. P., Saad, T., and S. Peng, [NRP-YANG] Wu, B., Dhody, D., Beeram, V. P., Saad, T., and S. Peng,
 End of changes. 43 change blocks. 
147 lines changed or deleted 145 lines changed or added

This html diff was produced by rfcdiff 1.48.