MPLS Working Group X. Min Internet-Draft P. Shaofu Intended status: Standards Track ZTE Corp. Expires: 20 May 2022 16 November 2021 Label Switched Path (LSP) Ping for Segment Routing (SR) Path Segment Identifiers (SIDs) with MPLS Data Planes draft-xp-mpls-spring-lsp-ping-path-sid-02 Abstract Path Segment is a type of SR segment, which is used to identify an SR path. This document provides Target Forwarding Equivalence Class (FEC) stack TLV definitions for Path Segment Identifiers. 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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Min & Shaofu Expires 20 May 2022 [Page 1] Internet-Draft LSP Ping for SR Path SID November 2021 Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 2. Conventions . . . . . . . . . . . . . . . . . . . . . . . . . 2 2.1. Requirements Language . . . . . . . . . . . . . . . . . . 2 2.2. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3 3. Path Segment ID Sub-TLV . . . . . . . . . . . . . . . . . . . 3 3.1. SR Candidate Path's Path SID . . . . . . . . . . . . . . 3 3.2. SR Segment List's Path SID . . . . . . . . . . . . . . . 6 4. Path-SID FEC Validation . . . . . . . . . . . . . . . . . . . 8 5. Security Considerations . . . . . . . . . . . . . . . . . . . 11 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 11 7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 12 8. References . . . . . . . . . . . . . . . . . . . . . . . . . 12 8.1. Normative References . . . . . . . . . . . . . . . . . . 12 8.2. Informative References . . . . . . . . . . . . . . . . . 13 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 15 1. Introduction Path Segment is a type of SR segment, which is used to identify an SR path. Path Segment in MPLS based segment routing network is defined in [I-D.ietf-spring-mpls-path-segment]. When Path Segment is used, it's inserted by the ingress node of the SR path, and then processed by the egress node of the SR path. The position of Path Segment Label within the MPLS label stack is immediately following the segment list of the SR path. Note that the Path Segment would not be popped up until it reaches the egress node. This document provides Target Forwarding Equivalence Class (FEC) stack TLV definitions for Path-SIDs. Procedures for LSP Ping as defined in [RFC8287] and [RFC8690] are applicable to Path-SIDs as well. 2. Conventions 2.1. Requirements Language The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all capitals, as shown here. Min & Shaofu Expires 20 May 2022 [Page 2] Internet-Draft LSP Ping for SR Path SID November 2021 2.2. Terminology This document uses the terminology defined in [RFC8402] and [RFC8029], readers are expected to be familiar with those terms. 3. Path Segment ID Sub-TLV Analogous to what's defined in Section 5 of [RFC8287] and Section 4 of [I-D.ietf-mpls-sr-epe-oam], two new sub-TLVs are defined for the Target FEC Stack TLV (Type 1), the Reverse-Path Target FEC Stack TLV (Type 16), and the Reply Path TLV (Type 21). Sub-Type Sub-TLV Name -------- ----------------------------- TBD1 SR Candidate Path's Path SID TBD2 SR Segment List's Path SID As specified in Section 3 of [I-D.ietf-idr-sr-policy-path-segment], the Path Segment can be used to identify an SR path (specified by SID list) or an SR candidate path, so two different Target FEC sub-TLVs need to be defined for Path Segment ID. When a Path Segment is used to identify an SR path, then the Target FEC sub-TLV of SR Segment List's Path SID would be used to validate the control plane to forwarding plane synchronization for this Path-SID; When a Path Segment is used to identify an SR candidate path, then the Target FEC sub-TLV of SR Candidate Path's Path SID would be used to validate the control plane to forwarding plane synchronization for this Path-SID. Note that the two new Target FEC sub-TLVs are mutual exclusive and they wouldn't be present in one message simultaneously. 3.1. SR Candidate Path's Path SID The format of SR Candidate Path's Path SID sub-TLV is as specified below: Min & Shaofu Expires 20 May 2022 [Page 3] Internet-Draft LSP Ping for SR Path SID November 2021 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Type = TBD1 | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ ~ Headend (4/16 octets) ~ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Color (4 octets) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ ~ Endpoint (4/16 octets) ~ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |Protocol-Origin| Reserved | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | | | | Originator (20 octets) | | | | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Discriminator (4 octets) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 1: SR Candidate Path's Path SID sub-TLV Type This field is set to the value (TBD1) which indicates that it's a SR Candidate Path's Path SID sub-TLV. Length This field is set to the length of the sub-TLV's Value field in octets. If Headend and Endpoint fields are in IPv4 address format which is 4 octets long, it MUST be set to 40; If Headend and Endpoint fields are in IPv6 address format which is 16 octets long, it MUST be set to 64. Headend This field identifies the headend of an SR Policy, the same as defined in Section 2.1 of [I-D.ietf-spring-segment-routing-policy]. The headend is a 4-octet IPv4 address or a 16-octet IPv6 address. Color Min & Shaofu Expires 20 May 2022 [Page 4] Internet-Draft LSP Ping for SR Path SID November 2021 This field associates the SR Policy with an intent, the same as defined in Section 2.1 of [I-D.ietf-spring-segment-routing-policy]. The color is a 4-octet numerical value. Endpoint This field identifies the endpoint of an SR Policy, the same as defined in Section 2.1 of [I-D.ietf-spring-segment-routing-policy]. The endpoint is a 4-octet IPv4 address or a 16-octet IPv6 address. Protocol-Origin This field identifies the component or protocol that originates or signals the candidate path for an SR Policy, the same as defined in Section 2.3 of [I-D.ietf-spring-segment-routing-policy]. The protocol-origin is a 1-octet value that follows the recommendation from Table 1 of Section 2.3 of [I-D.ietf-spring-segment-routing-policy], which specifies value 10 for "PCEP", value 20 for "BGP SR Policy" and value 30 for "Via Configuration". Originator This field identifies the node which provisioned or signaled the candidate path for an SR Policy, the same as defined in Section 2.4 of [I-D.ietf-spring-segment-routing-policy]. The originator is a 20-octet numerical value formed by the concatenation of the fields of the tuple , among which ASN is a 4-octet number and node address is a 16-octet value (an IPv6 address or an IPv4 address encoded in the lowest 4 octets). When Procotol-Origin is respectively "Via Configuration", or "PCEP", or "BGP SR Policy", the values of ASN and node address follow the specification in Section 2.4 of [I-D.ietf-spring-segment-routing-policy]. Discriminator This field uniquely identifies a candidate path within the context of an SR policy, the same as defined in Section 2.5 of [I-D.ietf-spring-segment-routing-policy]. The discriminator is a 4-octet value. When Protocol-Origin is respectively "Via Configuration", or "PCEP", or "BGP SR Policy", the value of discriminator follows the specification in Section 2.5 of [I-D.ietf-spring-segment-routing-policy]. Min & Shaofu Expires 20 May 2022 [Page 5] Internet-Draft LSP Ping for SR Path SID November 2021 3.2. SR Segment List's Path SID The format of SR Segment List's Path SID sub-TLV is as specified below: 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Type = TBD2 | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ ~ Headend (4/16 octets) ~ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Color (4 octets) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ ~ Endpoint (4/16 octets) ~ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |Protocol-Origin| Reserved | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | | | | Originator (20 octets) | | | | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Discriminator (4 octets) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Segment-List-ID (4 octets) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 2: SR Segment List's Path SID sub-TLV Type This field is set to the value (TBD2) which indicates that it's a SR Segment List's Path SID sub-TLV. Length This field is set to the length of the sub-TLV's Value field in octets. If Headend and Endpoint fields are in IPv4 address format which is 4 octets long, it MUST be set to 44; If Headend and Endpoint fields are in IPv6 address format which is 16 octets long, it MUST be set to 68. Headend Min & Shaofu Expires 20 May 2022 [Page 6] Internet-Draft LSP Ping for SR Path SID November 2021 This field identifies the headend of an SR Policy, the same as defined in Section 2.1 of [I-D.ietf-spring-segment-routing-policy]. The headend is a 4-octet IPv4 address or a 16-octet IPv6 address. Color This field associates the SR Policy with an intent, the same as defined in Section 2.1 of [I-D.ietf-spring-segment-routing-policy]. The color is a 4-octet numerical value. Endpoint This field identifies the endpoint of an SR Policy, the same as defined in Section 2.1 of [I-D.ietf-spring-segment-routing-policy]. The endpoint is a 4-octet IPv4 address or a 16-octet IPv6 address. Protocol-Origin This field identifies the component or protocol that originates or signals the candidate path for an SR Policy, the same as defined in Section 2.3 of [I-D.ietf-spring-segment-routing-policy]. The protocol-origin is a 1-octet value that follows the recommendation from Table 1 of Section 2.3 of [I-D.ietf-spring-segment-routing-policy], which specifies value 10 for "PCEP", value 20 for "BGP SR Policy" and value 30 for "Via Configuration". Originator This field identifies the node which provisioned or signaled the candidate path for an SR Policy, the same as defined in Section 2.4 of [I-D.ietf-spring-segment-routing-policy]. The originator is a 20-octet numerical value formed by the concatenation of the fields of the tuple , among which ASN is a 4-octet number and node address is a 16-octet value (an IPv6 address or an IPv4 address encoded in the lowest 4 octets). When Procotol-Origin is respectively "Via Configuration", or "PCEP", or "BGP SR Policy", the values of ASN and node address follow the specification in Section 2.4 of [I-D.ietf-spring-segment-routing-policy]. Discriminator Min & Shaofu Expires 20 May 2022 [Page 7] Internet-Draft LSP Ping for SR Path SID November 2021 This field uniquely identifies a candidate path within the context of an SR policy, the same as defined in Section 2.5 of [I-D.ietf-spring-segment-routing-policy]. The discriminator is a 4-octet value. When Protocol-Origin is respectively "Via Configuration", or "PCEP", or "BGP SR Policy", the value of discriminator follows the specification in Section 2.5 of [I-D.ietf-spring-segment-routing-policy]. Segment-List-ID This field identifies an SR path within the context of a candidate path of an SR Policy, the same as "Path ID" defined in Section 4.2 of [I-D.ietf-pce-multipath], or "List Identifier" defined in Section 2.2 of [I-D.lp-idr-sr-path-protection]. The segment-list- ID is a 4-octet identifier of the corresponding segment list. 4. Path-SID FEC Validation The MPLS LSP Ping procedures MAY be initiated by the headend of the Segment Routing path or a centralized topology-aware data plane monitoring system as described in [RFC8403]. For the Path-SID, the responder nodes that receive echo request and send echo reply MUST be the endpoint of the Segment Routing path. When an endpoint receives the LSP echo request packet with top FEC being the Path-SID, it SHOULD perform validity checks on the content of the Path-SID FEC sub-TLV. The basic length check should be performed on the received FEC. SR Candidate Path's Path SID ------------------ Length = 40 or 64 SR Segment List's Path SID ------------------ Length = 44 or 68 If a malformed FEC sub-TLV is received, then a return code of 1, "Malformed echo request received" as defined in [RFC8029] SHOULD be sent. The below section augments the section 7.4 of [RFC8287]. 4a. Segment Routing Path-SID Validation: If the Label-stack-depth is 0 and the Target FEC Stack sub-TLV at FEC-stack-depth is TBD1 (SR Candidate Path's Path SID sub-TLV), { Min & Shaofu Expires 20 May 2022 [Page 8] Internet-Draft LSP Ping for SR Path SID November 2021 - Set the Best-return-code to 10, "Mapping for this FEC is not the given label at stack-depth " if any below conditions fail: o Validate that the Path Segment ID is signaled or provisioned for the SR Candidate Path { + When the Protocol-Origin field in the received SR Candidate Path's Path SID sub-TLV is 10, "PCEP" is used as the signaling protocol. And then validate that the Path Segment ID matches with the tuple identifying the SR Candidate Path within PCEP { * Validate that the signaled headend, color, end-point, originator ASN, originator address and discriminator defined in [I-D.ietf-pce-segment-routing-policy-cp] and [I-D.ietf-pce-sr-path-segment], for the Path SID, matches with the corresponding fields in the received SR Candidate Path's Path SID sub-TLV. } + When the Protocol-Origin field in the received SR Candidate Path's Path SID sub-TLV is 20, "BGP SR Policy" is used as the signaling protocol. And then validate that the Path Segment ID matches with the tuple identifying the SR Candidate Path within BGP SR Policy { * Validate that the signaled headend, policy color, endpoint, ASN, BGP Router-ID and distinguisher defined in [I-D.ietf-idr-segment-routing-te-policy] and [I-D.ietf-idr-sr-policy-path-segment], for the Path SID, matches with the corresponding fields in the received SR Candidate Path's Path SID sub-TLV. } + When the Protocol-Origin field in the received SR Candidate Path's Path SID sub-TLV is 30, "Via Configuration" is used. And then validate that the Path Segment ID matches with the tuple identifying the SR Candidate Path within Configuration { * Validate that the provisioned headend, color, endpoint, originator and discriminator defined in [I-D.ietf-spring-sr-policy-yang], for the Path SID, matches with the corresponding fields in the received SR Candidate Path's Path SID sub-TLV. Min & Shaofu Expires 20 May 2022 [Page 9] Internet-Draft LSP Ping for SR Path SID November 2021 } } - If all the above validations have passed, set the return code to 3 "Replying router is an egress for the FEC at stack-depth ". - Set FEC-Status to 1 and return. } Else, if the Label-stack-depth is 0 and the Target FEC Stack sub- TLV at FEC-stack-depth is TBD2 (SR Segment List's Path SID sub- TLV), { - Set the Best-return-code to 10, "Mapping for this FEC is not the given label at stack-depth " if any below conditions fail: o Validate that the Path Segment ID is signaled or provisioned for the SR Segment List { + When the Protocol-Origin field in the received SR Segment List's Path SID sub-TLV is 10, "PCEP" is used as the signaling protocol. And then validate that the Path Segment ID matches with the tuple identifying the SR Segment List within PCEP { * Validate that the signaled headend, color, end-point, originator ASN, originator address and discriminator defined in [I-D.ietf-pce-segment-routing-policy-cp] and [I-D.ietf-pce-sr-path-segment], and the signaled Path ID defined in [I-D.ietf-pce-multipath], for the Path SID, matches with the corresponding fields in the received SR Segment List's Path SID sub-TLV. } + When the Protocol-Origin field in the received SR Segment List's Path SID sub-TLV is 20, "BGP SR Policy" is used as the signaling protocol. And then validate that the Path Segment ID matches with the tuple identifying the SR Segment List within BGP SR Policy { * Validate that the signaled headend, policy color, endpoint, ASN, BGP Router-ID and distinguisher defined in [I-D.ietf-idr-segment-routing-te-policy] and Min & Shaofu Expires 20 May 2022 [Page 10] Internet-Draft LSP Ping for SR Path SID November 2021 [I-D.ietf-idr-sr-policy-path-segment], and the signaled List Identifier defined in [I-D.lp-idr-sr-path-protection], for the Path SID, matches with the headend field in the received SR Segment List's Path SID sub-TLV. } + When the Protocol-Origin field in the received SR Segment List's Path SID sub-TLV is 30, "Via Configuration" is used. And then validate that the Path Segment ID matches with the tuple identifying the SR Segment List within Configuration { * Validate that the provisioned headend, color, endpoint, originator, discriminator and Segment-List- ID defined in [I-D.ietf-spring-sr-policy-yang], for the Path SID, matches with the corresponding fields in the received SR Segment List's Path SID sub-TLV. } } - If all the above validations have passed, set the return code to 3 "Replying router is an egress for the FEC at stack-depth ". - Set FEC-Status to 1 and return. } 5. Security Considerations This document does not raise any additional security issues beyond those of the specifications referred to in the list of normative references. 6. IANA Considerations IANA is requested to assign two new sub-TLVs from the "sub-TLVs for TLV Types 1, 16, and 21" subregistry of the "Multi-Protocol Label Switching (MPLS) Label Switched Paths (LSPs) Ping Parameters" registry [IANA]. Min & Shaofu Expires 20 May 2022 [Page 11] Internet-Draft LSP Ping for SR Path SID November 2021 Sub-Type Sub-TLV Name Reference -------- ----------------------------- ------------ TBD1 SR Candidate Path's Path SID Section 3.1 TBD2 SR Segment List's Path SID Section 3.2 7. Acknowledgements The authors would like to acknowledge Zhao Detao for his thorough review and very helpful comments. The authors would like to acknowledge Liu Yao for very helpful discussion with her. 8. References 8.1. Normative References [I-D.ietf-spring-mpls-path-segment] Cheng, W., Li, H., Chen, M., Gandhi, R., and R. Zigler, "Path Segment in MPLS Based Segment Routing Network", Work in Progress, Internet-Draft, draft-ietf-spring-mpls-path- segment-05, 21 August 2021, . [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997, . [RFC8029] Kompella, K., Swallow, G., Pignataro, C., Ed., Kumar, N., Aldrin, S., and M. Chen, "Detecting Multiprotocol Label Switched (MPLS) Data-Plane Failures", RFC 8029, DOI 10.17487/RFC8029, March 2017, . [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, May 2017, . [RFC8287] Kumar, N., Ed., Pignataro, C., Ed., Swallow, G., Akiya, N., Kini, S., and M. Chen, "Label Switched Path (LSP) Ping/Traceroute for Segment Routing (SR) IGP-Prefix and IGP-Adjacency Segment Identifiers (SIDs) with MPLS Data Planes", RFC 8287, DOI 10.17487/RFC8287, December 2017, . Min & Shaofu Expires 20 May 2022 [Page 12] Internet-Draft LSP Ping for SR Path SID November 2021 [RFC8690] Nainar, N., Pignataro, C., Iqbal, F., and A. Vainshtein, "Clarification of Segment ID Sub-TLV Length for RFC 8287", RFC 8690, DOI 10.17487/RFC8690, December 2019, . 8.2. Informative References [I-D.ietf-idr-segment-routing-te-policy] Previdi, S., Filsfils, C., Talaulikar, K., Mattes, P., Rosen, E., Jain, D., and S. Lin, "Advertising Segment Routing Policies in BGP", Work in Progress, Internet- Draft, draft-ietf-idr-segment-routing-te-policy-13, 7 June 2021, . [I-D.ietf-idr-sr-policy-path-segment] Li, C., Li, Z., Yin, Y., Cheng, W., and K. Talaulikar, "SR Policy Extensions for Path Segment and Bidirectional Path", Work in Progress, Internet-Draft, draft-ietf-idr- sr-policy-path-segment-04, 8 July 2021, . [I-D.ietf-mpls-sr-epe-oam] Hegde, S., Arora, K., Srivastava, M., Ninan, S., and X. Xu, "Label Switched Path (LSP) Ping/Traceroute for Segment Routing (SR) Egress Peer Engineering Segment Identifiers (SIDs) with MPLS Data Planes", Work in Progress, Internet- Draft, draft-ietf-mpls-sr-epe-oam-04, 8 November 2021, . [I-D.ietf-pce-multipath] Koldychev, M., Sivabalan, S., Saad, T., Beeram, V. P., Bidgoli, H., Yadav, B., and S. Peng, "PCEP Extensions for Signaling Multipath Information", Work in Progress, Internet-Draft, draft-ietf-pce-multipath-03, 25 October 2021, . [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, . Min & Shaofu Expires 20 May 2022 [Page 13] Internet-Draft LSP Ping for SR Path SID November 2021 [I-D.ietf-pce-sr-path-segment] Li, C., Chen, M., Cheng, W., Gandhi, R., and Q. Xiong, "Path Computation Element Communication Protocol (PCEP) Extension for Path Segment in Segment Routing (SR)", Work in Progress, Internet-Draft, draft-ietf-pce-sr-path- segment-04, 12 August 2021, . [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-14, 25 October 2021, . [I-D.ietf-spring-sr-policy-yang] Raza, K., Sawaya, R., Shunwan, Z., Voyer, D., Durrani, M., Matsushima, S., and V. P. Beeram, "YANG Data Model for Segment Routing Policy", Work in Progress, Internet-Draft, draft-ietf-spring-sr-policy-yang-01, 7 April 2021, . [I-D.lp-idr-sr-path-protection] Yao, L. and P. Shaofu, "BGP Extensions of SR Policy for Path Protection", Work in Progress, Internet-Draft, draft- lp-idr-sr-path-protection-01, 19 May 2021, . [IANA] Internet Assigned Numbers Authority (IANA), "Multi- Protocol Label Switching (MPLS) Label Switched Paths (LSPs) Ping Parameters", . [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, . [RFC8403] Geib, R., Ed., Filsfils, C., Pignataro, C., Ed., and N. Kumar, "A Scalable and Topology-Aware MPLS Data-Plane Monitoring System", RFC 8403, DOI 10.17487/RFC8403, July 2018, . Min & Shaofu Expires 20 May 2022 [Page 14] Internet-Draft LSP Ping for SR Path SID November 2021 Authors' Addresses Xiao Min ZTE Corp. Nanjing China Phone: +86 25 88013062 Email: xiao.min2@zte.com.cn Peng Shaofu ZTE Corp. Nanjing China Email: peng.shaofu@zte.com.cn Min & Shaofu Expires 20 May 2022 [Page 15]