Interdomain Routing Working Group H. Wang
Internet-Draft J. Dong
Intended status: Informational Huawei Technologies
Expires: 28 August 2025 K. Talaulikar
Cisco Systems
T. Han
Huawei Technologies
R. Chen
ZTE Corporation
24 February 2025
BGP Colored Prefix Routing (CPR) for SRv6 based Services
draft-ietf-idr-cpr-08
Abstract
This document describes a mechanism to advertise IPv6 prefixes in BGP
which are associated with Color Extended Communities to establish
end-to-end intent-aware paths for Segment Routing over IPv6 (SRv6)
services. Such IPv6 prefixes are called "Colored Prefixes", and this
mechanism is called Colored Prefix Routing (CPR). In SRv6 networks,
the Colored prefixes are the SRv6 locators associated with different
intent. SRv6 services (e.g. SRv6 VPN services) with specific intent
could be assigned with SRv6 Segment Identifiers (SIDs) under the
corresponding SRv6 locators, which are advertised as Colored
prefixes.
This operational methodology allows the SRv6 service traffic to be
steered into end-to-end intent-aware paths simply based on the
longest prefix matching of SRv6 Service SIDs to the Colored prefixes.
The existing IPv6 Address Family and Color Extended Community are
reused for the advertisement of IPv6 Colored prefixes without new BGP
extensions, thus this mechanism is easy to interoperate and can be
deployed incrementally in multi-Autonomous System (AS) networks which
belong to the same trusted domain.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at https://datatracker.ietf.org/drafts/current/.
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Internet-Drafts are draft documents valid for a maximum of six months
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time. It is inappropriate to use Internet-Drafts as reference
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This Internet-Draft will expire on 28 August 2025.
Copyright Notice
Copyright (c) 2025 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents (https://trustee.ietf.org/
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Please review these documents carefully, as they describe your rights
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. BGP CPR . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
2.1. Colored Prefix Allocation . . . . . . . . . . . . . . . . 4
2.2. Colored Prefix Advertisement . . . . . . . . . . . . . . 5
2.3. CPR to Intra-domain Path Resolution . . . . . . . . . . . 6
2.4. SRv6 Service Route Advertisement . . . . . . . . . . . . 7
2.5. SRv6 Service Steering . . . . . . . . . . . . . . . . . . 7
3. Encapsulation and Forwarding Processes . . . . . . . . . . . 7
3.1. CPR over SRv6 Intra-Domain Paths . . . . . . . . . . . . 8
3.2. CPR over MPLS Intra-Domain Paths . . . . . . . . . . . . 8
4. Operational Considerations . . . . . . . . . . . . . . . . . 9
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 11
6. Security Considerations . . . . . . . . . . . . . . . . . . . 11
7. Contributing Authors . . . . . . . . . . . . . . . . . . . . 12
8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 12
9. References . . . . . . . . . . . . . . . . . . . . . . . . . 12
9.1. Normative References . . . . . . . . . . . . . . . . . . 12
9.2. Informative References . . . . . . . . . . . . . . . . . 13
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 14
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1. Introduction
With the trend of using one common network to carry multiple types of
services, each service type can have different requirements for the
network. Such requirements are usually considered as the "intent" of
the service or customer, and is represented as an abstract notion
called "color".
In network scenarios where the services are delivered across multiple
Autonomous Systems (ASes) , there is a need to provide the services
with different end-to-end paths to meet the intent.
[I-D.hr-spring-intentaware-routing-using-color] describes the problem
statements and requirements for inter-domain intent-aware routing.
The inter-domain path can be established using either Multi-Protocol
Label Switching (MPLS) or IP data plane. In MPLS-based networks, the
usual inter-domain approach is to establish an end-to-end Label-
Switched Path (LSP) based on the BGP Labeled Unicast (BGP-LU)
mechanism as defined in [RFC8277]. Each domain's ingress border node
needs to perform label swapping for the end-to-end LSP, and impose
the label stack which is used for the LSP within its own domain.
In IP-based networks, the IP reachability information can be
advertised to network nodes in different domains using BGP, so that
all the domain border nodes can obtain the routes to the IP prefixes
of the destination nodes in other domains. With the introduction of
SRv6 [RFC8402] [RFC8754] [RFC8986], BGP services are assigned with
SRv6 Service SIDs [RFC9252], which are routable in the network
according to its SRv6 locator prefix. Thus, the inter-domain path
can be established simply based on the inter-domain routes to the
prefix, and inter-domain LSPs based on BGP-LU mechanism is not
necessary for IPv6 and SRv6-based networks.
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This document describes a mechanism to advertise IPv6 prefixes which
are associated with Color Extended Community to establish end-to-end
intent-aware paths for SRv6 services. The color value in the Color
Extended Community indicates the intent [RFC9256]. Such IPv6
prefixes are called "Colored Prefixes", and this mechanism is called
Colored Prefix Routing (CPR). In SRv6 networks, the Colored Prefixes
are the SRv6 locators associated with different intent. BGP services
over SRv6 (e.g. SRv6 VPN services) [RFC9252] with specific intent
could be assigned with SRv6 SIDs under the corresponding SRv6
locators, which are advertised as Colored Prefixes. This allows the
SRv6 service traffic to be steered (as specified in [RFC9252]) into
end-to-end intent-aware paths simply based on the longest prefix
matching of SRv6 Service SIDs to the Colored Prefixes. In the data
plane, the dedicated transport label or SID for the inter-domain path
is not needed, resulting in smaller encapsulation overhead than with
other options.
The existing IPv6 Address Family and Color Extended Community could
be reused for the advertisement of IPv6 Colored Prefixes without new
BGP extensions, thus this mechanism is easy to interoperate and can
be deployed incrementally in multi-AS networks which belong to the
same trusted domain (in the sense used by Section 8 of [RFC8402]).
2. BGP CPR
2.1. Colored Prefix Allocation
In SRv6 networks, an SRv6 locator needs to be allocated for each
node. In order to distinguish N different intents, a Provider Edge
(PE) node needs to be allocated with N SRv6 locators, each of which
is associated a different intent that is identified by a color value.
One way to achieve this is by splitting the base SRv6 locator of the
node into N sub-locators, and these sub-locators are Colored Prefixes
associated with different intents.
For example, a PE node is allocated with the base SRv6 Locator
2001:db8:aaaa:1::/64. In order to provide 16 different intents, this
base SRv6 Locator is split into 16 sub-locators from
2001:db8:aaaa:1:0000::/68 to 2001:db8:aaaa:1:F000::/68, each of these
sub-locators is associated with a different intent, such as low-
delay, high-bandwidth, etc.
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2.2. Colored Prefix Advertisement
After the allocation of Colored Prefixes on a PE node, routes to
these Colored Prefixes need to be advertised both in the local domain
and also to other domains using BGP, so that the BGP SRv6 services
routes could be resolved using the corresponding CPR route.
In a multi-AS IPv6 network, the IPv6 unicast Address Family/
Subsequent Address Family (AFI/SAFI = 2/1) [RFC2545] is used for the
advertisement of the Colored Prefix routes. The color extended
community [RFC9012] is carried with the Colored Prefix route with the
color value indicating the intent [RFC9256]. The procedure of
Colored Prefix advertisement is described using an example with the
following topology:
Consistent Color Domain:
C1, C2, ...
+--------------+ +--------------+ +-------------+
| | | | | |
| [ASBR11]---[ASBR21] [ASBR23]---[ASBR31] |
--[PE1] [P1] | X | [P2] | X | [P3] [PE3]--
| [ASBR12]---[ASBR22] [ASBR24]---[ASBR32] |
| | | | | |
+--------------+ +--------------+ +-------------+
AS1 AS2 AS3
Colored Prefixes of PE3:
Low delay: PE3:CL1::
High bandwidth: PE3:CL2::
...
Figure 1. Example Topology for CPR Route Illustration
Assume PE3 is provisioned with two different Colored Prefixes CLP-1
and CLP-2 for two different intents such as "low-delay" and "high-
bandwidth" respectively. In this example, It is assumed that the
color representing a specific intent is consistent throughout all the
domains.
* PE3 originates BGP IPv6 unicast (AFI/SAFI=2/1) route for the
Colored Prefixes PE3:CL1:: and PE3:CL2::. Each route should carry
the corresponding color extended community C1 or C2. PE3 also
advertises a route for the base SRv6 Locator prefix PE3:BL, and
there is no color extended community carried with this route.
* ASBR31 and ASBR32 receive the CPR routes of PE3, and advertise the
CPR routes further to ASBR23 and ASBR24 with next-hop set to
itself.
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* ASBR23 and ASBR24 receive the CPR routes of PE3. Since the color-
to-intent mapping in AS2 is consistent with that in AS3, the Color
Extended Community in the received CPR routes are kept unchanged.
ASBR23 and ASBR 24 advertise the CPR routes further in AS2 with
the next-hop set to itself.
* The behavior of ASBR21 and ASBR22 are similar to the behavior of
ASBR31 and ASBR32.
* The behavior of ASBR11 and ASBR12 are similar to the behavior of
ASBR23 and ASBR24.
In normal cases, the color value in the color extended community
associated with the CPR route is consistent through all the domains,
so that the Color Extended Community in the CPR routes is kept
unchanged. While in some special cases, one intent may be
represented as different color value in different domains. If this
is the case, then the Color Extended Community in the CPR routes
needs to be updated at the border nodes of the domains based on the
color-mapping policy. For example, in AS1, the intent "low latency"
is represented by color "red", while in AS2 the same intent is
represented by color "blue". When a CPR route is sent from AS1 to
AS2, the Color Extended Community in the CPR routes needs to be
updated from "red" to "blue" at the border nodes based on the color-
mapping policy.
In network scenarios where some of the intermediate autonomous
systems are MPLS-based, the CPR routes may still be advertised using
the IPv6 unicast address family (AFI/SAFI=2/1) in the MPLS-based
intermediate domains, and at the MPLS domain border nodes, some route
resolution policy could be used to make the CPR routes resolved to
intra-domain intent-aware MPLS LSPs. Another possible mechanism is
to use the IPv6 LU address family (AFI/SAFI=2/4) to advertise the CPR
routes in the MPLS domains, the detailed procedure is described in
Section 7.1.2.1 of [I-D.ietf-spring-srv6-mpls-interworking].
2.3. CPR to Intra-domain Path Resolution
A domain border node which receives a CPR route can resolve the CPR
route to an intra-domain color-aware path based on the tuple (N, C),
where N is the next-hop of the CPR route, and C is the color extended
community of the CPR route. The intra-domain color-aware path could
be built with any of the following mechanisms:
* SRv6 or SR-MPLS Policy
* SRv6 or SR-MPLS Flex-Algo
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* RSVP-TE
For example, PE1 receives a CPR route to PE3:CL1:: with color C1 and
next-hop ASBR11, it can resolve the CPR routes to an intra-domain
SRv6 Policy based on the tuple (ASBR11, C1).
The intra-domain path resolution scheme could be based on any
existing tunnel resolution policy, and new tunnel resolution
mechanisms could be introduced if needed.
2.4. SRv6 Service Route Advertisement
For an SRv6 service which is associated with a specific intent, the
SRv6 Service SID could be allocated under the corresponding Colored
locator prefix. For example, on PE3 in the example topology, an SRv6
VPN service with the low-delay intent can be allocated with the SRv6
End.DT4 SID PE3:CL1:DT::, where PE3:CL1:: is the SRv6 Colored Prefix
for low-delay service.
The SRv6 service routes are advertised using the mechanism defined in
[RFC9252]. The inter-domain VPN Option C is used, which means the
next-hop of the SRv6 service route is set to the originating PE and
not changed. Since the intent of the service is embedded in the SRv6
service SID, the SRv6 service route does not need to carry the color
extended community.
2.5. SRv6 Service Steering
With the CPR routing mechanism, the ingress PE node which receives
the SRv6 service routes follows the behavior of SRv6 shortest path
forwarding (refer to Section 5 and 6 of [RFC9252]). The SRv6 service
SID carried in the service route is used as the destination address
in the outer IPv6 header that encapsulates the service packet. If
the corresponding CPR route has been received and installed, longest
prefix matching of SRv6 service SIDs to the Colored Prefixes is
performed. As a result of this prefix matching, the next hop found
is an intra-domain color-aware path, which will be used for
forwarding the SRv6 service traffic. This process repeats at the
border node of each domain the packet traverses, until it reaches its
destination.
3. Encapsulation and Forwarding Processes
This section describes the encapsulation and forwarding process of
data packets which are matched with the corresponding CPR route.
The topology of Figure 1 is used in each example.
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3.1. CPR over SRv6 Intra-Domain Paths
Following is an illustration of the packet encapsulation and
forwarding process of CPR over SRv6 Policy. The abstract
representation of IPv6 and SRH in section 6 of [RFC8754] is used.
PE3 is provisioned with a Colored Prefix PE3:CL1:: for "low-delay".
In AS1, the SRv6 Policy on PE1 for (ASBR11, C1) is represented with
SID list <P1, ASBR11>.
In AS2, the SRv6 Policy on ASBR21 for (ASBR23, C1) is represented
with the SID list <P2, ASBR23>.
In AS3, the SRv6 Policy on ASBR31 for (PE3, C1) is represented with
the SID list <P3, PE3>.
C-pkt is the customer packet PE1 received from its attaching CE.
For packets which belong to an SRv6 VPN service associated with the
SRv6 Service SID PE3:CL1.DT6, the packet encapsulation and forwarding
process using H.Encaps.Red behavior [RFC8986] is shown as below:
PE1 ->P1: (PE1, P1)(PE3:CL1.DT6, ASBR11; SL=2)(C-pkt)
P1 ->ASBR11: (PE1, ASBR11)(PE3:CL1.DT6, ASBR11; SL=1)(C-pkt)
ASBR11->ASBR21: (PE1, PE3:CL1.DT6)(C-pkt)
ASBR21->P2: (ASBR21, P2)(ASBR23; SL=1)(PE1, PE3:CL1.DT6)(C-pkt)
P2->ASBR23: (ASBR21, ASBR23)(PE1, PE3:CL1.DT6)(C-pkt)
ASBR23->ASBR31: (PE1, PE3:CL1.DT6)(C-pkt)
ASBR31->P3: (ASBR31, P3)(PE3; SL=1)(PE1, PE3:CL1.DT6)(C-pkt)
P3->PE3: (ASBR31, PE3)(PE1, PE3:CL1.DT6)(C-pkt)
In some autonomous systems, SRv6 Flex-Algo may be used to provide
intent-aware intra-domain paths. The encapsulation is similar to the
case with SRv6 Policy.
3.2. CPR over MPLS Intra-Domain Paths
In network scenarios where some of the autonomous systems use MPLS
based data plane, the CPR route can be resolved over a color-aware
intra-domain MPLS LSP. Such intra-domain MPLS LSP may be established
using SR-MPLS Policy, SR-MPLS Flex-Algo or RSVP-TE.
The encapsulation and forwarding of SRv6 service packets (which are
actually IPv6 packets) over an intra-domain MPLS LSP is based on the
MPLS mechanisms as defined in [RFC3031] [RFC3032] and [RFC8660]. The
behavior is similar to that of 6PE [RFC4798].
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In AS1, the SR-MPLS Policy on PE1 for (ASBR11, C1) is represented
with SID list <P1, ASBR11>.
In AS2, the SR-MPLS Flex-Algo on ASBR21 for (ASBR23, C1) is
represented with SID list <ASBR23>.
In AS3, the SR-MPLS Policy on ASBR31 for (PE3, C1) is represented
with SID list <P3, PE3>.
C-pkt is the customer packet PE-1 received from its attaching CE.
For packets which belong to an SRv6 VPN service associated with the
SRv6 Service SID PE3:CL1.DT6, the packet encapsulation and forwarding
process is shown as below:
PE1-> P1: Label-stack(P1, ASBR11)(PE1, PE3:CL1.DT6)(C-pkt)
P1->ASBR11: Label-stack(ASBR11)(PE1, PE3:CL1.DT6)(C-pkt)
ASBR11->ASBR21: (PE1, PE3:CL1.DT6)(C-pkt)
ASBR21->P2: Label-stack(ASBR23)(PE1, PE3:CL1.DT6)(C-pkt)
P2->ASBR23: Label-stack(ASBR23)(PE1, PE3:CL1.DT6)(C-pkt)
ASBR23->ASBR31: (PE1, PE3:CL1.DT6)(C-pkt)
ASBR31->P3: Label-stack(P3, PE3)(PE1, PE3:CL1.DT6)(C-pkt)
P3->PE3: Label-stack(PE3)(PE1, PE3:CL1.DT6)(C-pkt)
4. Operational Considerations
The CPR mechanism can be used in network scenarios where multiple
inter-connected ASes belong to the same operator, or there is an
operational trust model between the ASes of different operators which
makes them belonging to the same trusted domain (in the sense used by
Section 8 of [RFC8402]).
As described in section 5 of
[I-D.hr-spring-intentaware-routing-using-color], the inter-domain
intent-aware routing may be achieved with a logical tunnel created by
an SR Policy across multiple ASes, and service traffic with specific
intent can be steered to the inter-domain SR Policy based on the
intent signaled by Color Extended Community. An operator may prefer
a BGP routing based solution for the reasons described in
[I-D.hr-spring-intentaware-routing-using-color]. Another possible
consideration of the operator is the availability of inter-domain
controller for end-to-end intent-aware path computation. This
document proposes an alternate solution to signal the intent with
IPv6 Colored Prefixes using BGP.
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When the Colored Prefixes are assigned as the sub-locators of the
node's base SRv6 locator, the IPv6 unicast route of the base locator
prefix is the covering prefix of all the Colored locator prefixes.
To make sure the Colored locator prefixes can be distributed to the
ingress PE nodes along the border nodes, it is required that the
route aggregation be disabled for IPv6 unicast routes which carry the
color extended community.
With CPR mechanism, at the prefix originator, each colored prefix is
associated with one specific intent (i.e. color). And in each
domain, according to the color mapping policy, the same CPR route is
always updated with the same color. The case where there are
multiple copies of CPR routes with the same colored prefix but
different color extened commuity is considered a misconfiguration.
All the border nodes and the ingress PE nodes need to install the
Colored locator prefixes into the RIB and FIB. For transit domains
which support the CPR mechanism, the border nodes can use the tuple
(N, C) where N is next hop and C is color, to resolve the CPR routes
to intent-aware intra-domain paths. For transit domains which do not
support the CPR mechanism, the border nodes would ignore the color
extended community and resolve the CPR routes over a best-effort
intra-domain path to the next-hop N, while the CPR route will be
advertised further to the downstream domains with only the next-hop
changed to itself. This allows the CPR routes to be resolved to
intent-aware intra-domain paths in any autonomous systems that
support the CPR mechanism, while can fall back to resolve over best-
effort intra-domain path in the legacy autonomous systems.
There may be multiple inter-domain links between the adjacent
autonomous systems, and a border node BGP speaker may receive CPR
routes from multiple peering BGP speakers in another domain via EBGP.
The local policy of a BGP speaker may take the attributes of the
inter-domain links and the attributes of the received CPR routes into
consideration when selecting the best path for specific Colored
Prefixes to better meet the intent. The detailed local policy is
outside the scope of this document. In a multi-AS environment, the
policy of BGP speakers in different domains needs to be consistent.
In this document, IPv6 Unicast Address Family is used for the
advertisement of IPv6 Colored Prefixes. The primary advantage of
this approach is the improved interoperability with legacy networks
that lack support for intent-aware paths, and the facilitation of
incremental deployment of intent-aware routing mechanisms. One
potential concern arises regarding the necessity of separating
Colored Prefixes from public IPv6 unicast routes. Since the IP
prefixes and SRv6 locators of network infrastructure are usually
advertised as part of the IP unicast routes, and appropriate filters
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are configured at the boundaries of network administration, this is
not considered to be a significant issue. [RFC9602] allocates the
prefix 5f00::/16 for SRv6 SIDs, by common agreement among
participants in the trusted domain, the filters can be configured to
by default drop all traffic from 5f00::/16 but permit the colored
prefixes in use in these domains. The proposal in
[I-D.ietf-idr-bgp-car] provides a complementary solution that is also
based on the notion of color indicating the intent and where the SRv6
Locator prefix itself signifies the intent, the difference is that a
separate SAFI is used.
[I-D.ietf-idr-bgp-ct] describes another mechanism for intent-aware
routing, in which the SRv6 service SIDs are not directly associated
with the intent, while additional SRv6 transport SIDs are required
for steering traffic to the inter-domain intent-aware paths, and an
SRv6 operation similar to MPLS label swapping is needed on the border
nodes of autonomous systems.
5. IANA Considerations
This document makes no request of IANA.
6. Security Considerations
The mechanism described in this document provides an approach for
inter-domain intent-aware routing based on existing BGP protocol
mechanisms. The existing BGP IPv6 Unicast Address Family and
existing Color extended community are reused without further BGP
extensions. With this approach, the number of IPv6 Colored Prefixes
advertised by PE nodes is in proportion to the number of intents it
supports. This may introduce additional routes to BGP IPv6 routing
table. While since these are infrastructure routes, the amount of
Colored Prefixes is only a small portion of the total amount of IPv6
prefixes. Thus it is considered that the impact to the required
routing table size is acceptable.
As the CPR routes are distributed across multiple ASes which belong
to a trusted domain, the mapping relationship between the intent and
the IPv6 Colored Prefixes are observable to BGP nodes in those ASes.
It is possible for an on-path attacker in the trusted domain to
identify packets associated with a particular intent.
The security considerations as described in [RFC4271] [RFC4272] and
[RFC8754] apply to this document.
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7. Contributing Authors
The following people contributed significantly to the content of this
document and should be considered co-authors:
Xinjun Chen
ifocus.chen@huawei.com
Jingrong Xie
xiejingrong@huawei.com
Zhenqiang Li
li_zhenqiang@hotmail.com
8. Acknowledgements
The authors would like to thank Shunwan Zhuang, Zhibo Hu, Zhenbin Li,
Dhananjaya Rao and Dhruv Dhody for the review and valuable
discussion.
9. References
9.1. Normative References
[RFC2545] Marques, P. and F. Dupont, "Use of BGP-4 Multiprotocol
Extensions for IPv6 Inter-Domain Routing", RFC 2545,
DOI 10.17487/RFC2545, March 1999,
<https://www.rfc-editor.org/info/rfc2545>.
[RFC4271] Rekhter, Y., Ed., Li, T., Ed., and S. Hares, Ed., "A
Border Gateway Protocol 4 (BGP-4)", RFC 4271,
DOI 10.17487/RFC4271, January 2006,
<https://www.rfc-editor.org/info/rfc4271>.
[RFC4272] Murphy, S., "BGP Security Vulnerabilities Analysis",
RFC 4272, DOI 10.17487/RFC4272, January 2006,
<https://www.rfc-editor.org/info/rfc4272>.
[RFC8402] Filsfils, C., Ed., Previdi, S., Ed., Ginsberg, L.,
Decraene, B., Litkowski, S., and R. Shakir, "Segment
Routing Architecture", RFC 8402, DOI 10.17487/RFC8402,
July 2018, <https://www.rfc-editor.org/info/rfc8402>.
[RFC8754] Filsfils, C., Ed., Dukes, D., Ed., Previdi, S., Leddy, J.,
Matsushima, S., and D. Voyer, "IPv6 Segment Routing Header
(SRH)", RFC 8754, DOI 10.17487/RFC8754, March 2020,
<https://www.rfc-editor.org/info/rfc8754>.
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[RFC8986] Filsfils, C., Ed., Camarillo, P., Ed., Leddy, J., Voyer,
D., Matsushima, S., and Z. Li, "Segment Routing over IPv6
(SRv6) Network Programming", RFC 8986,
DOI 10.17487/RFC8986, February 2021,
<https://www.rfc-editor.org/info/rfc8986>.
[RFC9012] Patel, K., Van de Velde, G., Sangli, S., and J. Scudder,
"The BGP Tunnel Encapsulation Attribute", RFC 9012,
DOI 10.17487/RFC9012, April 2021,
<https://www.rfc-editor.org/info/rfc9012>.
[RFC9252] Dawra, G., Ed., Talaulikar, K., Ed., Raszuk, R., Decraene,
B., Zhuang, S., and J. Rabadan, "BGP Overlay Services
Based on Segment Routing over IPv6 (SRv6)", RFC 9252,
DOI 10.17487/RFC9252, July 2022,
<https://www.rfc-editor.org/info/rfc9252>.
[RFC9256] Filsfils, C., Talaulikar, K., Ed., Voyer, D., Bogdanov,
A., and P. Mattes, "Segment Routing Policy Architecture",
RFC 9256, DOI 10.17487/RFC9256, July 2022,
<https://www.rfc-editor.org/info/rfc9256>.
9.2. Informative References
[I-D.hr-spring-intentaware-routing-using-color]
Hegde, S., Rao, D., Uttaro, J., Bogdanov, A., and L.
Jalil, "Problem statement for Inter-domain Intent-aware
Routing using Color", Work in Progress, Internet-Draft,
draft-hr-spring-intentaware-routing-using-color-04, 31
January 2025, <https://datatracker.ietf.org/doc/html/
draft-hr-spring-intentaware-routing-using-color-04>.
[I-D.ietf-idr-bgp-car]
Rao, D. and S. Agrawal, "BGP Color-Aware Routing (CAR)",
Work in Progress, Internet-Draft, draft-ietf-idr-bgp-car-
16, 20 February 2025,
<https://datatracker.ietf.org/doc/html/draft-ietf-idr-bgp-
car-16>.
[I-D.ietf-idr-bgp-ct]
Vairavakkalai, K. and N. Venkataraman, "BGP Classful
Transport Planes", Work in Progress, Internet-Draft,
draft-ietf-idr-bgp-ct-38, 19 February 2025,
<https://datatracker.ietf.org/doc/html/draft-ietf-idr-bgp-
ct-38>.
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Internet-Draft BGP CPR for SRv6 Services February 2025
[I-D.ietf-spring-srv6-mpls-interworking]
Agrawal, S., Filsfils, C., Voyer, D., Dawra, G., Li, Z.,
and S. Hegde, "SRv6 and MPLS interworking", Work in
Progress, Internet-Draft, draft-ietf-spring-srv6-mpls-
interworking-00, 17 October 2024,
<https://datatracker.ietf.org/doc/html/draft-ietf-spring-
srv6-mpls-interworking-00>.
[RFC3031] Rosen, E., Viswanathan, A., and R. Callon, "Multiprotocol
Label Switching Architecture", RFC 3031,
DOI 10.17487/RFC3031, January 2001,
<https://www.rfc-editor.org/info/rfc3031>.
[RFC3032] Rosen, E., Tappan, D., Fedorkow, G., Rekhter, Y.,
Farinacci, D., Li, T., and A. Conta, "MPLS Label Stack
Encoding", RFC 3032, DOI 10.17487/RFC3032, January 2001,
<https://www.rfc-editor.org/info/rfc3032>.
[RFC4798] De Clercq, J., Ooms, D., Prevost, S., and F. Le Faucheur,
"Connecting IPv6 Islands over IPv4 MPLS Using IPv6
Provider Edge Routers (6PE)", RFC 4798,
DOI 10.17487/RFC4798, February 2007,
<https://www.rfc-editor.org/info/rfc4798>.
[RFC8277] Rosen, E., "Using BGP to Bind MPLS Labels to Address
Prefixes", RFC 8277, DOI 10.17487/RFC8277, October 2017,
<https://www.rfc-editor.org/info/rfc8277>.
[RFC8660] Bashandy, A., Ed., Filsfils, C., Ed., Previdi, S.,
Decraene, B., Litkowski, S., and R. Shakir, "Segment
Routing with the MPLS Data Plane", RFC 8660,
DOI 10.17487/RFC8660, December 2019,
<https://www.rfc-editor.org/info/rfc8660>.
[RFC9602] Krishnan, S., "Segment Routing over IPv6 (SRv6) Segment
Identifiers in the IPv6 Addressing Architecture",
RFC 9602, DOI 10.17487/RFC9602, October 2024,
<https://www.rfc-editor.org/info/rfc9602>.
Authors' Addresses
Haibo Wang
Huawei Technologies
China
Email: rainsword.wang@huawei.com
Wang, et al. Expires 28 August 2025 [Page 14]
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Jie Dong
Huawei Technologies
China
Email: jie.dong@huawei.com
Ketan Talaulikar
Cisco Systems
India
Email: ketant.ietf@gmail.com
Tao Han
Huawei Technologies
China
Email: hantao@huawei.com
Ran Chen
ZTE Corporation
China
Email: chen.ran@zte.com.cn
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