Network Working Group Z. Li Internet-Draft J. Mao Intended status: Standards Track C. Li Expires: 26 November 2024 Huawei Technologies 25 May 2024 Generalized Arguments of SRv6 Segment draft-lm-spring-srv6-generalized-arguments-03 Abstract This document analyzes the challenges of Arguments of SRv6 SID, and the chance of using Arguments of SRv6 SID to reduce the length of the IPv6 extension header. According to these analysis, this document specifies a kind of generalized and structured Arguments for SRv6 SID, which can carry multiple Arguments parts for a SRv6 SID. 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 26 November 2024. 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. Li, et al. Expires 26 November 2024 [Page 1] Internet-Draft Generalized Arguments May 2024 Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 2. Requirements Language . . . . . . . . . . . . . . . . . . . . 2 3. Terminologies . . . . . . . . . . . . . . . . . . . . . . . . 2 4. Problem Statement and Requirements . . . . . . . . . . . . . 2 5. Generalized Arguments . . . . . . . . . . . . . . . . . . . . 4 5.1. Method A . . . . . . . . . . . . . . . . . . . . . . . . 4 5.2. Method B . . . . . . . . . . . . . . . . . . . . . . . . 4 5.3. Consideration of SRv6 C-SID Compression . . . . . . . . . 5 6. Flavor for Generalized Arguments . . . . . . . . . . . . . . 6 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6 8. Security Considerations . . . . . . . . . . . . . . . . . . . 6 9. References . . . . . . . . . . . . . . . . . . . . . . . . . 6 9.1. Normative References . . . . . . . . . . . . . . . . . . 6 9.2. Informative References . . . . . . . . . . . . . . . . . 7 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 8 1. Introduction This document analyzes the challenges of the Arguments of SRv6 SID, and the chance of using Arguments of SRv6 SID to reduce the length of the IPv6 extension header. According to these analysis, this document specifies a kind of generalized and structured arguments for SRv6 SID, which can carry multiple Arguments parts for a SRv6 SID. 2. 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 RFC 2119 [RFC2119] RFC 8174 [RFC8174] when, and only when, they appear in all capitals, as shown here. 3. Terminologies SRv6: Segment Routing over IPv6 4. Problem Statement and Requirements With the development of SRv6, several kinds of SRv6 Arguments for the SRv6 End SID and End.X SID emerge[I-D.ietf-spring-srv6-srh-compression], including: 1. SRv6 C-SID compression (NEXT Flavor): using Arguments to carry multiple C-SIDs. Li, et al. Expires 26 November 2024 [Page 2] Internet-Draft Generalized Arguments May 2024 2. SRv6 C-SID compression (REPLACE Flavor): using Arguments to carry the CL field. 3. SRv6 C-SID compression (NEXT & REPLACE Flavor): using Arguments to carry multiple C-SIDs and the CL field. In addition, some new features are created, including network slicing[I-D.ietf-6man-enhanced-vpn-vtn-id], IOAM[RFC9197], Alternate Marking[RFC9343][I-D.fz-spring-srv6-alt-mark], APN6[I-D.li-apn-ipv6-encap][I-D.li-apn-header], DetNet[I-D.pthubert-detnet-ipv6-hbh], etc. The instructions of these new features can be processed at: 1. All nodes along a SR path: the instructions can be carried in the IPv6 Hop-by-Hop Options header (HBH). 2. Endpoints of an SR path: the ones can be carried in the IPv6 Destination Options Header (DOH) or the SRH TLV. In the second scenario, especially the second one, the usages of the options or TLVs will cause the following two issues: 1. Lengthening the packet header, and reducing the transmission efficiency. 2. Making the forwarding processing complex, affecting forwarding performance. Besides these issues, in the SRv6 C-SID compression (NEXT Flavor) solution, if all the C-SIDs of the SID list which should have been encapsulated in the SRH can be put in the IPv6 destination address of the packet, because there is no SRH or DOH before SRH any more after the compression there will be no space for the instructions which should have been encapsulated in the IPv6 SRH or Destination Options Header before SRH. In order to address these challenges, a feasible solution is to use the Arguments of the SRv6 SID to carry those instructions. Using SRv6 Arguments to do that will bring following benefits: 1. Reducing the needed space of IPv6 extension header or SRH TLV, so as to reduce the transmission overhead. Li, et al. Expires 26 November 2024 [Page 3] Internet-Draft Generalized Arguments May 2024 2. SRv6 SID can reside in the IPv6 destination address field, so the SRv6 Arguments can be read and processed as a part of IPv6 address, from which the forwarding performance will benefit, because it avoids to process the extension header or SRv6 TLV behind the IPv6 header. 3. Unify and simplify the processing: the instructions of both the SRv6 and the new features are all put in the Arguments part of SRv6 SID or IPv6 address. 5. Generalized Arguments In order to carry the instructions of multiple features in the SRv6 Arguments, this section defines two methods to make the SRv6 Arguments generalized and structured to allocate spaces for the instructions. 5.1. Method A Network devices are configured a template for the purpose of parsing the SRv6 Arguments, and the devices read and process the content of the Arguments according to the template. The template defines what features are carried, and which bits they are used. For example, if the length of the Arguments is z bits and the number x, y, and z have the relationship 0. Li, et al. Expires 26 November 2024 [Page 6] Internet-Draft Generalized Arguments May 2024 [RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for Writing an IANA Considerations Section in RFCs", BCP 26, RFC 8126, DOI 10.17487/RFC8126, June 2017, . [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, May 2017, . 9.2. Informative References [I-D.fz-spring-srv6-alt-mark] Fioccola, G., Zhou, T., Cociglio, M., Mishra, G. S., wang, X., and G. Zhang, "Application of the Alternate Marking Method to the Segment Routing Header", Work in Progress, Internet-Draft, draft-fz-spring-srv6-alt-mark-08, 8 February 2024, . [I-D.ietf-6man-enhanced-vpn-vtn-id] Dong, J., Li, Z., Xie, C., Ma, C., and G. S. Mishra, "Carrying Network Resource Partition (NRP) Information in IPv6 Extension Header", Work in Progress, Internet-Draft, draft-ietf-6man-enhanced-vpn-vtn-id-06, 20 February 2024, . [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-17, 16 May 2024, . [I-D.li-apn-header] Li, Z., Peng, S., and S. Zhang, "Application-aware Networking (APN) Header", Work in Progress, Internet- Draft, draft-li-apn-header-04, 12 April 2023, . [I-D.li-apn-ipv6-encap] Li, Z., Peng, S., and C. Xie, "Application-aware IPv6 Networking (APN6) Encapsulation", Work in Progress, Internet-Draft, draft-li-apn-ipv6-encap-07, 10 July 2023, . Li, et al. Expires 26 November 2024 [Page 7] Internet-Draft Generalized Arguments May 2024 [I-D.pthubert-detnet-ipv6-hbh] Thubert, P. and F. Yang, "IPv6 Options for DetNet", Work in Progress, Internet-Draft, draft-pthubert-detnet-ipv6- hbh-07, 22 February 2022, . [RFC3272] Awduche, D., Chiu, A., Elwalid, A., Widjaja, I., and X. Xiao, "Overview and Principles of Internet Traffic Engineering", RFC 3272, DOI 10.17487/RFC3272, May 2002, . [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, . [RFC9197] Brockners, F., Ed., Bhandari, S., Ed., and T. Mizrahi, Ed., "Data Fields for In Situ Operations, Administration, and Maintenance (IOAM)", RFC 9197, DOI 10.17487/RFC9197, May 2022, . [RFC9343] Fioccola, G., Zhou, T., Cociglio, M., Qin, F., and R. Pang, "IPv6 Application of the Alternate-Marking Method", RFC 9343, DOI 10.17487/RFC9343, December 2022, . Authors' Addresses Zhenbin Li Huawei Technologies Beijing 100095 China Email: lizhenbin@huawei.com Jianwei Mao Huawei Technologies Beijing 100095 China Li, et al. Expires 26 November 2024 [Page 8] Internet-Draft Generalized Arguments May 2024 Email: MaoJianwei@huawei.com Cheng Li Huawei Technologies Beijing 100095 China Email: c.l@huawei.com Li, et al. Expires 26 November 2024 [Page 9]