SPRING R. Chen Internet-Draft D. Zhao Intended status: Standards Track ZTE Corporation Expires: 21 April 2025 18 October 2024 SRv6 NET-PGM extension: Compressed BSID Insertion draft-chen-spring-srv6-compressed-bsid-insertion-00 Abstract The End.B6.Insert and End.B6.Insert.Red SHOULD support the NEXT-C-SID flavor either individually or in combinations. This document defines the SRH processing of the End.B6.Insert and End.B6.Insert.Red with NEXT-C-SID flavor. 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/. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." This Internet-Draft will expire on 21 April 2025. Copyright Notice Copyright (c) 2024 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/ license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Revised BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Revised BSD License. Chen & Zhao Expires 21 April 2025 [Page 1] Internet-Draft Compressed BSID Insertion October 2024 Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1.1. Requirements Language . . . . . . . . . . . . . . . . . . 2 2. SRv6 endpoint behaviors . . . . . . . . . . . . . . . . . . . 2 2.1. End.B6.Insert with NEXT-C-SID flavor . . . . . . . . . . 3 2.2. End.B6.Insert red with NEXT-C-SID flavor . . . . . . . . 5 3. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5 4. Security Considerations . . . . . . . . . . . . . . . . . . . 6 5. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 6 6. Normative References . . . . . . . . . . . . . . . . . . . . 6 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 7 1. Introduction [I-D.filsfils-spring-srv6-net-pgm-insertion] extends the SRv6 Network Programming [RFC8986] model with new endpoint and transit behaviors enabling the insertion of an SRH after the outer IPv6 header of the SR domain, called End.B6.Insert and End.B6.Insert.Red. [I-D.ietf-spring-srv6-srh-compression] specifies the new flavors to the SR segment endpoint behaviors defined in [RFC8986] that enable a compressed encoding of the SRv6 segment list. One of the flavor is the NEXT-C-SID flavor. With the NEXT-C-SID flavor, each C-SID container is a fully formed SRv6 SID with the common Locator-Block for all the C-SIDs in the C-SID container, a Locator-Node and Function that are those of the first C-SID, and an Argument carrying the subsequent C-SIDs. The End.B6.Insert and End.B6.Insert.Red SHOULD support the NEXT-C-SID flavor either individually or in combinations. This document defines the SRH processing of the End.B6.Insert and End.B6.Insert.Red with NEXT-C-SID flavor. 1.1. 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. 2. SRv6 endpoint behaviors This section defines the SRH processing of the End.B6.Insert and End.B6.Insert.Red with NEXT-C-SID flavor. Chen & Zhao Expires 21 April 2025 [Page 2] Internet-Draft Compressed BSID Insertion October 2024 2.1. End.B6.Insert with NEXT-C-SID flavor End.B6.Insert with NEXT-C-SID: Endpoint bound to an SRv6 policy. The "Endpoint bound to an SRv6 Policy" is a variant of the End behavior. When N receives a packet whose IPv6 DA is S and S matching a FIB entry locally instantiated as an End.B6.Insert SID with NEXT-C-SID Flavor, does: Chen & Zhao Expires 21 April 2025 [Page 3] Internet-Draft Compressed BSID Insertion October 2024 N01. If (DA.Argument != 0) { N02. If (IPv6 Hop Limit <= 1) { N03. Send an ICMP Time Exceeded message to the Source Address, Code 0 (Hop limit exceeded in transit), interrupt packet processing and discard the packet. N04. } N05. Copy DA.Argument into the bits [LBL..(LBL+AL-1)] of the Destination Address. N06. Set the bits [(LBL+AL)..127] of the Destination Address to zero. N07. Decrement IPv6 Hop Limit by 1. N08.1. Insert a new SRH in between the IPv6 Header and the received SRH containing the list of segments of B. N08.2. Set the new SRH[0] to the IPv6 DA . N08.3. Set the IPv6 DA to the first segment of B. N08.4. Submit the packet to the egress IPv6 FIB lookup for transmission to the next destination. N09. } S02. If (Segments Left == 0) { S03. Stop processing the SRH, and proceed to process the next header in the packet, whose type is identified by the Next Header field in the routing header. S04. } S05. If (IPv6 Hop Limit <= 1) { S06. Send an ICMP Time Exceeded message to the Source Address with Code 0 (Hop limit exceeded in transit), interrupt packet processing, and discard the packet. S07. } S08. max_LE = (Hdr Ext Len / 2) - 1 S09. If ((Last Entry > max_LE) or (Segments Left > Last Entry+1)) { S10. Send an ICMP Parameter Problem to the Source Address with Code 0 (Erroneous header field encountered) and Pointer set to the Segments Left field, interrupt packet processing, and discard the packet. S11. } S12. Decrement IPv6 Hop Limit by 1. S13. Decrement Segments Left by 1. S14. Update IPv6 DA with Segment List[Segments Left]. S15. Insert a new SRH in between the IPv6 Header and the received SRH containing the list of segments of B. S16. Set the IPv6 DA to the first SID of B. S17. Submit the packet to the egress IPv6 FIB lookup for transmission to the new destination. S18. } Examples: Chen & Zhao Expires 21 April 2025 [Page 4] Internet-Draft Compressed BSID Insertion October 2024 uBSID is an End.B6.Insert with NEXT-C-SID Flavor SID, and the corresponding segment-list is . case1, uBSID is the non-last SID of the container: Node N receives a packet: IPv6：SA = 2024::1, DA=FC00:2024:uBSID:uSID2:uSID3:uSID4::uSID5:uSID6:: SRH1:(FC00:2024:uSID7:uSID8::,FC00:2024:uBSID:uSID2:uSID3:uSID4:uSID5:uSID6::;SL=1) After the End.B6.Insert with NEXT-C-SID Flavor behavior, the packet looks like: IPv6：SA = 2024::1, DA=FC00:2024:uSID20:uSID21:: SRH2:(FC00:2024:uSID2:uSID3:uSID4::uSID5:uSID6::,FC00:2024:uSID20:uSID21::;SL=1) SRH1:(FC00:2024:uSID7:uSID8::,FC00:2024:uBSID:uSID2:uSID3:uSID4:uSID5:uSID6::;SL=1) case2, uBSID is the last SID of the C-SID container: Node N receives a packet: IPv6：SA = 2024::1, DA=FC00:2024:uBSID:: SRH1:(FC00:2024:uSID7:uSID8::,FC00:2024:uSID2:uSID3:uSID4:uSID5:uSID6:uBSID::;SL=1) After the End.B6.Insert with NEXT-C-SID Flavor behavior, the packet looks like: IPv6：SA = 2024::1, DA=FC00:2024:uSID20:uSID21:: SRH2:(FC00:2024:uSID20:uSID21::;SL=0);SRH2 may be omit SRH1:(FC00:2024:uSID7:uSID8::,FC00:2024:uSID2:uSID3:uSID4:uSID5:uSID6:uBSID::;SL=1) case3, uBSID is in the last of the C-SID container of the SRH: Node N receives a packet: IPv6：SA = 2024::1, DA=FC00:2024:uBSID:uSID7:uSID8:: SRH1:(FC00:2024:uBSID:uSID7:uSID8::,FC00:2024:uSID1:uSID2:uSID3:uSID4:uSID5:uSID6::;SL=0) After the End.B6.Insert with NEXT-C-SID Flavor behavior, the packet looks like: IPv6：SA = 2024::1, DA=FC00:2024:uSID20:uSID21:: SRH2:(FC00:2024:uSID7:uSID8::,FC00:2024:uSID20:uSID21::;SL=1) SRH1:(FC00:2024:uBSID:uSID7:uSID8::,FC00:2024:uSID1:uSID2:uSID3:uSID4:uSID5:uSID6::;SL=0) 2.2. End.B6.Insert red with NEXT-C-SID flavor This is an optimization of the End.B6.Insert with NEXT-C-SID flavor behavior. End.B6.Insert.Red with NEXT-C-SID flavor reduces the size of the new SRH by one SID by avoiding the insertion of the first SID in the pushed SRH. In this way, the first SID is only written in the DA and the packet is forwarded according to it. The new SRH is created as described in Section 4.1.1 of [RFC8754]. 3. IANA Considerations The document defines two new SRv6 Endpoint behaviors called End.B6.Insert with NEXT-C-SID flavor and End.B6.Insert.Red with NEXT- C-SID flavor. Chen & Zhao Expires 21 April 2025 [Page 5] Internet-Draft Compressed BSID Insertion October 2024 This document requests the IANA to allocate, within the "SRv6 Endpoint Behaviors" sub-registry belonging to the top-level "Segment- routing with IPv6 dataplane (SRv6) Parameters" registry, the following allocations: Value Endpoint Behavior Reference -------------------------------------------------------------------------- TBD1 End.B6.Insert with NEXT-C-SID flavor This document TBD2 End.B6.Insert.Red with NEXT-C-SID flavor This document Figure 1 4. Security Considerations The security requirements and mechanisms described in [RFC8402], [RFC8754] and [RFC8986] also apply to this document, and this document does not introduce any new security considerations. 5. Acknowledgements TBD. 6. Normative References [I-D.filsfils-spring-srv6-net-pgm-insertion] Filsfils, C., Camarillo, P., Leddy, J., Voyer, D., Matsushima, S., and Z. Li, "SRv6 NET-PGM extension: Insertion", Work in Progress, Internet-Draft, draft- filsfils-spring-srv6-net-pgm-insertion-09, 16 August 2023, . [I-D.ietf-spring-srv6-srh-compression] Cheng, W., Filsfils, C., Li, Z., Decraene, B., and F. Clad, "Compressed SRv6 Segment List Encoding", Work in Progress, Internet-Draft, draft-ietf-spring-srv6-srh- compression-18, 22 July 2024, . [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997, . [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, May 2017, . Chen & Zhao Expires 21 April 2025 [Page 6] Internet-Draft Compressed BSID Insertion October 2024 [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, . [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, . [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, . Authors' Addresses Ran Chen ZTE Corporation Nanjing China Email: chen.ran@zte.com.cn Detao Zhao ZTE Corporation Nanjing China Email: zhao.detao@zte.com.cn Chen & Zhao Expires 21 April 2025 [Page 7]