Network Working Group C. Schmutzer, Ed.
Internet-Draft C. Filsfils
Intended status: Informational Z. Ali, Ed.
Expires: 8 September 2022 F. Clad
Cisco Systems, Inc.
P. Maheshwari
Airtel India
7 March 2022
Circuit Style Segment Routing Policies
draft-schmutzer-pce-cs-sr-policy-01
Abstract
This document describes how Segment Routing (SR) policies can be used
to satisfy the requirements for strict bandwidth guarantees, end-to-
end recovery and persistent paths within a segment routing network.
SR policies satisfying these requirements are called "circuit-style"
SR policies (CS-SR policies).
Status of This Memo
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provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
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This Internet-Draft will expire on 8 September 2022.
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Copyright (c) 2022 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
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Please review these documents carefully, as they describe your rights
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extracted from this document must include Revised BSD License text as
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Reference Model . . . . . . . . . . . . . . . . . . . . . . . 4
4. CS-SR Policy Characteristics . . . . . . . . . . . . . . . . 5
5. CS-SR Policy Creation . . . . . . . . . . . . . . . . . . . . 5
6. Operations, Administration, and Maintenance (OAM) . . . . . . 6
6.1. Liveness . . . . . . . . . . . . . . . . . . . . . . . . 7
6.2. Performance Measurement . . . . . . . . . . . . . . . . . 7
7. Recovery Schemes . . . . . . . . . . . . . . . . . . . . . . 7
7.1. Unprotected . . . . . . . . . . . . . . . . . . . . . . . 7
7.2. 1+R Restoration . . . . . . . . . . . . . . . . . . . . . 8
7.3. 1:1 Protection . . . . . . . . . . . . . . . . . . . . . 8
7.4. 1:1+R Protection . . . . . . . . . . . . . . . . . . . . 9
7.5. External Commands . . . . . . . . . . . . . . . . . . . . 10
8. Security Considerations . . . . . . . . . . . . . . . . . . . 10
9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 10
10. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 10
11. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 10
12. References . . . . . . . . . . . . . . . . . . . . . . . . . 11
12.1. Normative References . . . . . . . . . . . . . . . . . . 11
12.2. Informative References . . . . . . . . . . . . . . . . . 11
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 15
1. Introduction
Segment routing does allow for a single network to carry both typical
IP (connection-less) services and connection-oriented transport
services. IP services required ECMP and TI-LFA, while transport
services that normally are delivered via dedicated circuit-switched
SONET/SDH or OTN networks do require:
* Persistent end2end traffic engineered paths that provide
predictable and identical latency in both directions
* Strict bandwidth commitment per path to ensure no impact on the
Service Level Agreement (SLA) due to changing network load from
other services
* End2end protection (<50msec protection switching) and restoration
mechanisms
* Monitoring and maintenance of path integrity
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* Data plane remaining up while control plane is down
Such a "transport centric" behaviour is referred to as "circuit-
style" in this document.
This document describes how SR policies
[I-D.ietf-spring-segment-routing-policy] and adjacency-SIDs defined
in the SR architecture [RFC8402] together with a stateful Path
Computation Element (PCE) [RFC8231] can be used to satisfy those
requirements. It includes how end-to-end recovery and path integrity
monitoring can be implemented.
SR policies that satisfy those requirements are called "circuit-
style" SR policies (CS-SR policies).
2. Terminology
* CS-SR : Circuit-Style Segment Routing
* ID : Identifier
* LSP : Label Switched Path
* LSPA : LSP attributes
* OAM : Operations, Administration and Maintenance
* OF : Objective Function
* PCE : Path Computation Element
* PCEP : Path Computation Element Communication Protocol
* PT : Protection Type
* SID : Segment Identifier
* SLA : Service Level Agreement
* SR : Segment Routing
* STAMP : Simple Two-Way Active Measurement Protocol
* TI-LFA : Topology Independent Loop Free Alternate
* TLV : Type Length Value
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3. Reference Model
The reference model for CS-SR policies is following the segment
routing architecture [RFC8402] and SR policy architecture
[I-D.ietf-spring-segment-routing-policy] and is depicted in Figure 1.
+--------------+
+-------------->| PCE |<--------------+
| +--------------+ |
| |
| |
v <<<<<<<<<<<<<< CS-SR Policy >>>>>>>>>>>>> v
+-------+ +-------+
| |=========================================>| |
| A | SR-policy from A to Z | Z |
| |<=========================================| |
+-------+ SR-policy from Z to A +-------+
Figure 1: Circuit-style SR Policy Architecture
By nature of CS-SR policies, paths will be computed and maintained by
a stateful PCE defined in [RFC8231]. When using a MPLS data plane
[RFC8660], PCEP extensions defined in [RFC8664] will be used. When
using a SRv6 data plane [RFC8754], PCEP extensions defined in
[I-D.ietf-pce-segment-routing-ipv6] will be used.
In order to satisfy the requirements of CS-SR policies, each link in
the topology MUST have:
* An adjacency-SID which is:
- Manually allocated or persistent : to ensure that its value
does not change after a node reload
- Non-protected : to avoid any local TI-LFA protection to happen
upon interface/link failures
* The bandwidth available for CS-SR policies
When using a MPLS data plane [RFC8660] existing IGP extensions
defined in [RFC8667] and [RFC8665] and BGP-LS defined in [RFC9085]
can be used to distribute the topology information including those
persistent and unprotected Adj-SIDs.
When using a SRv6 data plane [RFC8754] the IGP extensions defined in
[I-D.ietf-lsr-isis-srv6-extensions] and
[I-D.ietf-lsr-ospfv3-srv6-extensions] and BGP-LS extensions in
[I-D.ietf-idr-bgpls-srv6-ext] apply.
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4. CS-SR Policy Characteristics
A CS-SR policy has the following characteristics:
* Requested bandwidth : bandwidth to be reserved for the CS-SR
policy
* Bidirectional co-routed : a CS-SR policy between A and Z is an
association of an SR-Policy from A to Z and an SR-Policy from Z to
A following the same path(s)
* Deterministic and persistent paths : segment lists with strict
hops using unprotected adjacency-SIDs
* Not automatically recomputed or reoptimized : the SID list of a
candidate path must not change automatically (for example upon
topology change)
* Multiple candidate paths in case of protection/restoration:
- Following the SR policy architecture, the highest preference
valid path is carrying traffic
- Depending on the protection/restoration scheme (Section 7),
lower priority candidate paths
o may be pre-computed
o may be pre-programmed
o may have to be disjoint
* Liveness and performance measurement is activated on each
candidate path (Section 6)
5. CS-SR Policy Creation
A CS-SR policy between A and Z is configured both on A (with Z as
endpoint) and Z (with A as endpoint) as shown in Figure 1.
Both nodes A and Z act as PCC and delegate path computation to the
PCE using the extensions defined in [RFC8664]. The PCRpt message
sent from the headends to the PCE contains the following parameters:
* BANDWIDTH object (Section 7.7 of [RFC5440]) : to indicate the
requested bandwidth
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* LSPA object (section 7.11 of [RFC5440]) : to indicate that no
local protection requirements
- L flag set to 0 : no local protection
- E flag set to 1 : protection enforcement (section 5 of
[I-D.ietf-pce-local-protection-enforcement])
* ASSOCIATION object ([RFC8697]) :
- Type : Double-sided Bidirectional with Reverse LSP Association
([I-D.ietf-pce-sr-bidir-path])
- Bidirectional Association Group TLV ([RFC9059]) :
o R flag is always set to 0 (forward path)
o C flag is always set to 1 (co-routed)
If the SR-policies are configured with more than one candidate path,
a PCEP request is sent per candidate path. Each PCEP request does
include the "SR Policy Association" object (type 6) as defined in
[I-D.ietf-pce-segment-routing-policy-cp] to make the PCE aware of the
candidate path belonging to the same policy.
The signaling extensions described in
[I-D.sidor-pce-circuit-style-pcep-extensions] are used to ensure that
* Path determinism is achieved by the PCE only using segment lists
representing a strict hop by hop path using unprotected adjacency-
SIDs.
* Path persistency across node reloads in the network is achieved by
the PCE only including manually configured adj-SIDs in its path
computation response.
* Persistency across network changes is achieved by the PCE not
performing periodic nor network event triggered re-optimization.
Bandwidth adjustment can be requested after initial creation by
signaling both requested and operational bandwidth in the BANDWIDTH
object but the PCE is not allowed to respond with a changed path.
6. Operations, Administration, and Maintenance (OAM)
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6.1. Liveness
The proper operation of each segment list is validated by both
headends using STAMP in loopback measurement mode as described in
section 4.2.3 of [I-D.ietf-spring-stamp-srpm].
As the STAMP test packets are including both the segment list of the
forward and reverse path, standard segment routing data plane
operations will make those packets get switched along the forward
path to the tailend and along the reverse path back to the headend.
The headend forms the bidirectional SR Policy association using the
procedure described in [I-D.ietf-pce-sr-bidir-path] and receives the
information about the reverse segment list from the PCE as described
in section 4.5 of [I-D.ietf-pce-multipath]
6.2. Performance Measurement
The same STAMP session used for liveliness monitoring can be used to
measure delay. As loopback mode is used only round-trip delay is
measured and one-way has to be derived by dividing the round-trip
delay by two.
The same STAMP session can also be used to estimate round-trip loss
as described in section 5 of [I-D.ietf-spring-stamp-srpm].
7. Recovery Schemes
Various protection and restoration schemes can be implemented. The
terms "protection" and "restoration" are used with same subtle
distinctions outlined in section 1 of [RFC4872], [RFC4427] and
[RFC3386] respectively.
* Protection : another candidate path is computed and fully
established in the data plane and ready to carry traffic
* Restoration : a candidate path may be computed and may be
partially established but is not ready to carry traffic
7.1. Unprotected
In the most basic scenario no protection nor restoration is required.
The CS-SR policy has only one candidate path configured. This
candidate path is established, activated (O field in LSP object is
set to 2) and is carrying traffic.
In case of a failure the CS-SR policy will go down and traffic will
not be recovered.
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Typically two CS-SR policies are deployed either within the same
network with disjoint paths or in two completely separate networks
and the overlay service is responsible for traffic recovery.
7.2. 1+R Restoration
To avoid pre-allocating protection bandwidth in steady state
(Section 7.3) but still be able to react to network failures and
recover traffic flow in a deterministic way (maintain required
bandwidth commitment) the CS-SR policy is configured with two
candidate paths.
The candidate path with higher preference is established, activated
(O field in LSP object is set to 2) and is carrying traffic.
The second candidate path with lower preference is only established
and activated (O field in LSP object is set to 2) upon a failure
impacting the first candidate path in order to send traffic over an
alternate path through the network around the failure with
potentially relaxed constraints but still satisfying the bandwidth
commitment.
The second candidate path is generally only requested from the PCE
and activated after a failure, but may also be requested and pre-
established during CS-SR policy creation with the downside of
bandwidth being set aside ahead of time.
As soon as the failure that brought the first candidate path down is
cleared, the second candidate path is getting deactivated (O field in
LSP object is set to 1) or torn down. The first candidate path is
activated (O field in LSP object is set to 2) and traffic sent across
it.
Restoration and reversion behavior is bidirectional. As described in
Section 6.1, both headends use liveness in loopback mode and
therefore even in case of unidirectional failures both headends will
detect the failure or clearance of the failure and switch traffic
away from the failed or to the recovered candidate path.
7.3. 1:1 Protection
For fast recovery against failures the CS-SR policy is configured
with two candidate paths. Both paths are established but only the
candidate with higher preference is activated (O field in LSP object
is set to 2) and is carrying traffic. The candidate path with lower
preference has its O field in LSP object set to 1.
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Appropriate routing of the protect path diverse from the working path
can be requested from the PCE by using the "Disjointness Association"
object (type 2) defined in [RFC8800] in the PCRpt messages. The
disjoint requirements are communicated in the "DISJOINTNESS-
CONFIGURATION TLV"
* L bit set to 1 for link diversity
* N bit set to 1 for node diversity
* S bit set to 1 for SRLG diversity
* T bit set to enforce strict diversity
The P bit may be set for first candidate path to allow for finding
the best working path that does satisfy all constraints without
considering diversity to the protect path.
The "Objective Function (OF) TLV" as defined in section 5.3 of
[RFC8800] may also be added to minimize the common shared resources.
Upon a failure impacting the candidate path with higher preference
carrying traffic, the candidate path with lower preference is
activated immediately and traffic is now sent across it.
Protection switching is bidirectional. As described in Section 6.1,
both headends will generate and receive their own loopback mode test
packets, hence even a unidirectional failure will always be detected
by both headends without protection switch coordination required.
Two cases are to be considered when the failure impacting the
candidate path with higher preference is cleared:
* Revertive switching : re-activate the candidate path, change O
field from 0 to 2 and start sending traffic over it
* Non-revertive switching : do not activate the candidate path,
change O field from 0 to 1, keep the second candidate path active
with O field set to 2 and continue sending traffic over it
7.4. 1:1+R Protection
For further resiliency in case of multiple concurrent failures that
could affect both candidate paths in a Section 7.3 scenario the CS-SR
policy is configured with three candidate paths with decreasing
preference.
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The third candidate path enables restoration and will generally only
be established, activated (O field in LSP object is set to 2) and
carry traffic after failure(s) have impacted both the candidate path
with highest and second highest preference.
The third candidate path may also be requested and pre-computed
already whenever either the first or second candidate path went down
due to a failure with the downside of bandwidth being set aside ahead
of time.
As soon as failure(s) that brought either the first or second
candidate path down is cleared the third candidate path is getting
deactivated (O field in LSP object is set to 1), the candidate path
that recovered is activated (O field in LSP object is set to 2) and
traffic sent across it.
Protection switching, restoration and reversion behavior is
bidirectional. As described in Section 6.1, both headends use
liveness in loopback mode and therefore even in case of
unidirectional failures both headends will detect the failure or
clearance of the failure and switch traffic away from the failed or
to the recovered candidate path.
7.5. External Commands
It is very common to allow operators to trigger a switch between
candidate paths even no failure is present. I.e. to proactively
drain a resource for maintenance purposes. Operator triggered
switching between candidate paths is unidirectional and has to be
requested on both headends.
8. Security Considerations
TO BE ADDED
9. IANA Considerations
This document has no IANA actions.
10. Acknowledgements
The author's want to thank Samuel Sidor, Mike Koldychev, Rakesh
Gandhi for providing their review comments.
11. Contributors
Contributors' Addresses
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Brent Foster
Cisco Systems, Inc.
Email: brfoster@cisco.com
Bertrand Duvivier
Cisco System, Inc.
Email: bduvivie@cisco.com
Stephane Litkowski
Cisco Systems, Inc.
Email: slitkows@cisco.com
12. References
12.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>.
12.2. Informative References
[I-D.ietf-idr-bgpls-srv6-ext]
Dawra, G., Filsfils, C., Talaulikar, K., Chen, M.,
Bernier, D., and B. Decraene, "BGP Link State Extensions
for SRv6", Work in Progress, Internet-Draft, draft-ietf-
idr-bgpls-srv6-ext-09, 10 November 2021,
<https://www.ietf.org/archive/id/draft-ietf-idr-bgpls-
srv6-ext-09.txt>.
[I-D.ietf-lsr-isis-srv6-extensions]
Psenak, P., Filsfils, C., Bashandy, A., Decraene, B., and
Z. Hu, "IS-IS Extensions to Support Segment Routing over
IPv6 Dataplane", Work in Progress, Internet-Draft, draft-
ietf-lsr-isis-srv6-extensions-18, 20 October 2021,
<https://www.ietf.org/archive/id/draft-ietf-lsr-isis-srv6-
extensions-18.txt>.
[I-D.ietf-lsr-ospfv3-srv6-extensions]
Li, Z., Hu, Z., Cheng, D., Talaulikar, K., and P. Psenak,
"OSPFv3 Extensions for SRv6", Work in Progress, Internet-
Draft, draft-ietf-lsr-ospfv3-srv6-extensions-03, 19
November 2021, <https://www.ietf.org/archive/id/draft-
ietf-lsr-ospfv3-srv6-extensions-03.txt>.
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[I-D.ietf-pce-local-protection-enforcement]
Stone, A., Aissaoui, M., Sidor, S., and S. Sivabalan,
"Local Protection Enforcement in PCEP", Work in Progress,
Internet-Draft, draft-ietf-pce-local-protection-
enforcement-04, 30 January 2022,
<https://www.ietf.org/archive/id/draft-ietf-pce-local-
protection-enforcement-04.txt>.
[I-D.ietf-pce-multipath]
Koldychev, M., Sivabalan, S., Saad, T., Beeram, V. P.,
Bidgoli, H., Yadav, B., Peng, S., and G. Mishra, "PCEP
Extensions for Signaling Multipath Information", Work in
Progress, Internet-Draft, draft-ietf-pce-multipath-04, 25
February 2022, <https://www.ietf.org/archive/id/draft-
ietf-pce-multipath-04.txt>.
[I-D.ietf-pce-segment-routing-ipv6]
Li, C., Negi, M., Sivabalan, S., Koldychev, M.,
Kaladharan, P., and Y. Zhu, "PCEP Extensions for Segment
Routing leveraging the IPv6 data plane", Work in Progress,
Internet-Draft, draft-ietf-pce-segment-routing-ipv6-12, 6
March 2022, <https://www.ietf.org/internet-drafts/draft-
ietf-pce-segment-routing-ipv6-12.txt>.
[I-D.ietf-pce-segment-routing-policy-cp]
Koldychev, M., Sivabalan, S., Barth, C., Peng, S., and H.
Bidgoli, "PCEP extension to support Segment Routing Policy
Candidate Paths", Work in Progress, Internet-Draft, draft-
ietf-pce-segment-routing-policy-cp-06, 22 October 2021,
<https://www.ietf.org/archive/id/draft-ietf-pce-segment-
routing-policy-cp-06.txt>.
[I-D.ietf-pce-sr-bidir-path]
Li, C., Chen, M., Cheng, W., Gandhi, R., and Q. Xiong,
"Path Computation Element Communication Protocol (PCEP)
Extensions for Associated Bidirectional Segment Routing
(SR) Paths", Work in Progress, Internet-Draft, draft-ietf-
pce-sr-bidir-path-09, 6 March 2022,
<https://www.ietf.org/archive/id/draft-ietf-pce-sr-bidir-
path-09.txt>.
[I-D.ietf-spring-segment-routing-policy]
Filsfils, C., Talaulikar, K., Voyer, D., Bogdanov, A., and
P. Mattes, "Segment Routing Policy Architecture", Work in
Progress, Internet-Draft, draft-ietf-spring-segment-
routing-policy-20, 6 March 2022,
<https://www.ietf.org/archive/id/draft-ietf-spring-
segment-routing-policy-20.txt>.
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[I-D.ietf-spring-stamp-srpm]
Gandhi, R., Filsfils, C., Voyer, D., Chen, M., Janssens,
B., and R. Foote, "Performance Measurement Using Simple
TWAMP (STAMP) for Segment Routing Networks", Work in
Progress, Internet-Draft, draft-ietf-spring-stamp-srpm-03,
1 February 2022, <https://www.ietf.org/archive/id/draft-
ietf-spring-stamp-srpm-03.txt>.
[I-D.sidor-pce-circuit-style-pcep-extensions]
Sidor, S., Ali, Z., and P. Maheshwari, "PCEP extensions
for Circuit Style Policies", Work in Progress, Internet-
Draft, draft-sidor-pce-circuit-style-pcep-extensions-00, 7
March 2022, <https://www.ietf.org/archive/id/draft-sidor-
pce-circuit-style-pcep-extensions-00.txt>.
[RFC1925] Callon, R., "The Twelve Networking Truths", RFC 1925,
DOI 10.17487/RFC1925, April 1996,
<https://www.rfc-editor.org/info/rfc1925>.
[RFC3386] Lai, W., Ed. and D. McDysan, Ed., "Network Hierarchy and
Multilayer Survivability", RFC 3386, DOI 10.17487/RFC3386,
November 2002, <https://www.rfc-editor.org/info/rfc3386>.
[RFC4427] Mannie, E., Ed. and D. Papadimitriou, Ed., "Recovery
(Protection and Restoration) Terminology for Generalized
Multi-Protocol Label Switching (GMPLS)", RFC 4427,
DOI 10.17487/RFC4427, March 2006,
<https://www.rfc-editor.org/info/rfc4427>.
[RFC4872] Lang, J.P., Ed., Rekhter, Y., Ed., and D. Papadimitriou,
Ed., "RSVP-TE Extensions in Support of End-to-End
Generalized Multi-Protocol Label Switching (GMPLS)
Recovery", RFC 4872, DOI 10.17487/RFC4872, May 2007,
<https://www.rfc-editor.org/info/rfc4872>.
[RFC5440] Vasseur, JP., Ed. and JL. Le Roux, Ed., "Path Computation
Element (PCE) Communication Protocol (PCEP)", RFC 5440,
DOI 10.17487/RFC5440, March 2009,
<https://www.rfc-editor.org/info/rfc5440>.
[RFC8231] Crabbe, E., Minei, I., Medved, J., and R. Varga, "Path
Computation Element Communication Protocol (PCEP)
Extensions for Stateful PCE", RFC 8231,
DOI 10.17487/RFC8231, September 2017,
<https://www.rfc-editor.org/info/rfc8231>.
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[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>.
[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>.
[RFC8664] Sivabalan, S., Filsfils, C., Tantsura, J., Henderickx, W.,
and J. Hardwick, "Path Computation Element Communication
Protocol (PCEP) Extensions for Segment Routing", RFC 8664,
DOI 10.17487/RFC8664, December 2019,
<https://www.rfc-editor.org/info/rfc8664>.
[RFC8665] Psenak, P., Ed., Previdi, S., Ed., Filsfils, C., Gredler,
H., Shakir, R., Henderickx, W., and J. Tantsura, "OSPF
Extensions for Segment Routing", RFC 8665,
DOI 10.17487/RFC8665, December 2019,
<https://www.rfc-editor.org/info/rfc8665>.
[RFC8667] Previdi, S., Ed., Ginsberg, L., Ed., Filsfils, C.,
Bashandy, A., Gredler, H., and B. Decraene, "IS-IS
Extensions for Segment Routing", RFC 8667,
DOI 10.17487/RFC8667, December 2019,
<https://www.rfc-editor.org/info/rfc8667>.
[RFC8697] Minei, I., Crabbe, E., Sivabalan, S., Ananthakrishnan, H.,
Dhody, D., and Y. Tanaka, "Path Computation Element
Communication Protocol (PCEP) Extensions for Establishing
Relationships between Sets of Label Switched Paths
(LSPs)", RFC 8697, DOI 10.17487/RFC8697, January 2020,
<https://www.rfc-editor.org/info/rfc8697>.
[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>.
[RFC8800] Litkowski, S., Sivabalan, S., Barth, C., and M. Negi,
"Path Computation Element Communication Protocol (PCEP)
Extension for Label Switched Path (LSP) Diversity
Constraint Signaling", RFC 8800, DOI 10.17487/RFC8800,
July 2020, <https://www.rfc-editor.org/info/rfc8800>.
Schmutzer, et al. Expires 8 September 2022 [Page 14]
Internet-Draft cs-srte March 2022
[RFC9059] Gandhi, R., Ed., Barth, C., and B. Wen, "Path Computation
Element Communication Protocol (PCEP) Extensions for
Associated Bidirectional Label Switched Paths (LSPs)",
RFC 9059, DOI 10.17487/RFC9059, June 2021,
<https://www.rfc-editor.org/info/rfc9059>.
[RFC9085] Previdi, S., Talaulikar, K., Ed., Filsfils, C., Gredler,
H., and M. Chen, "Border Gateway Protocol - Link State
(BGP-LS) Extensions for Segment Routing", RFC 9085,
DOI 10.17487/RFC9085, August 2021,
<https://www.rfc-editor.org/info/rfc9085>.
Authors' Addresses
Christian Schmutzer (editor)
Cisco Systems, Inc.
Email: cschmutz@cisco.com
Clarence Filsfils
Cisco Systems, Inc.
Email: cfilsfil@cisco.com
Zafar Ali (editor)
Cisco Systems, Inc.
Email: zali@cisco.com
Francois Clad
Cisco Systems, Inc.
Email: fclad@cisco.com
Praveen Maheshwari
Airtel India
Email: Praveen.Maheshwari@airtel.com
Schmutzer, et al. Expires 8 September 2022 [Page 15]