SPRING WG R. Chen Internet-Draft Sh. Peng Intended status: Standards Track ZTE Expires: 30 September 2023 29 March 2023 SRv6 SID Allocation draft-cp-spring-srv6-sid-allocation-02 Abstract This document describes a SRv6 SID allocation method. 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 30 September 2023. Copyright Notice Copyright (c) 2023 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 & Peng Expires 30 September 2023 [Page 1] Internet-Draft SRv6 SID Allocation March 2023 Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 2. Conventions used in this document . . . . . . . . . . . . . . 2 3. Allocating a SRv6 Compressed SID to a node . . . . . . . . . 2 4. The New SR Endpoint Behaviors . . . . . . . . . . . . . . . . 3 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5 6. Security Considerations . . . . . . . . . . . . . . . . . . . 5 7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 5 8. Normative References . . . . . . . . . . . . . . . . . . . . 5 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 5 1. Introduction Segment Routing architecture [RFC8402]leverages the paradigm of source routing. It can be realized in a network data plane by prepending the packet with a list of instructions, a.k.a. Segment Identifiers (SIDs). A segment can be encoded as a Multi-Protocol Label Switching (MPLS) label, IPv4 address, or IPv6 address. Segment Routing can be applied in MPLS data plane by encoding 20-bits SIDs in MPLS label stack [RFC8660]. It also can be applied to IPv6 data plane by encoding a list of 128-bits SIDs in IPv6 Segment Routing Extension Header (SRH)[RFC8754]. As we know, several proposals are introduced to reduce the overhead of SIDs. The main ideas of them are basically to use a Compressed SID to replace the complete 128 bit SID in the SID list. The consequence of this is that the SID allocation space provided to each node will be very limited, which will limit the deployment of services in the network. This document describes an SRv6 SID allocation method to increase the SID allocation space. 2. Conventions used in this document The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in RFC2119. 3. Allocating a SRv6 Compressed SID to a node Assign a general global SRv6 SID to the corresponding consumer type, which is called the container SID. In the SID List, the container SID is followed by the local index or identification to indicate a specific segment with complete meaning. The container SID itself is 128bits and can be compressed to a short SID (such as 32 bits or 16 bits). The local index or identifier in general can also be a short Chen & Peng Expires 30 September 2023 [Page 2] Internet-Draft SRv6 SID Allocation March 2023 SID. For example, END.X SIDs [RFC8986] are allocated to all outbound L3 links on SRv6 nodes, and all these END.X SIDs occupy the global SRv6 SID resource. Now we define a new allocation method: for the consumer type of L3 link, only one general global container SID (called END.T.X SID) is allocated, and then allocates a local index for each specific L3 link, and the combination of END.T.X SID and local index can express the meaning of the original END.X. 4. The New SR Endpoint Behaviors This document defines a new set of behaviors. Following is a set of behaviors that can be associated with a SID. Chen & Peng Expires 30 September 2023 [Page 3] Internet-Draft SRv6 SID Allocation March 2023 END.T.X SID Endpoint with Layer-3 cross-connect. Only one universal container SID (END.T.X SID) is allocated on each node, and each outbound L3 link is represented by a local index. END.T.DX6 SID Endpoint with decapsulation and IPv6 cross-connect. Only one universal container SID (END.T.DX6 SID) is allocated on each node, and each L3 link connecting the CE is represented by a local index. END.T.DX4 SID Endpoint with decaps and IPv4 cross-connect. Only one universal container SID (END.T.DX4 SID) is allocated on each node, and each L3 link connecting the CE is represented by a local index. END.T.DT6 SID Endpoint with decapsulation and IPv6 table lookup. Only one universal container SID (END.T.DT6 SID) is allocated on each node, and each L3VPN instance is represented by a local index. END.T.DT4 SID Endpoint with decapsulation and IPv4 table lookup. Only one universal container SID (END.T.DT4 SID) is allocated on each node, and each L3VPN instance is represented by a local index. END.T.DT46 SID Endpoint with decapsulation and IP table lookup. Only one universal container SID (END.T.DT46 SID) is allocated on each node, and each L3VPN instance is represented by a local index. END.T.DX2 SID Endpoint with decapsulation and L2 cross-connect. Only one universal container SID (END.T.DX2 SID) is allocated on each node, and each L2 link connecting the CE is represented by a local index. END.T.DX2V SID Endpoint with decapsulation and VLAN L2 table lookup. Only one universal container SID (END.T.DX2V SID) is allocated on each node, and each L2VPN/EVPN instance is represented by a local index. END.T.DT2U SID Endpoint with decapsulation and unicast MAC L2table lookup. Only one universal container SID (END.T.DT2U SID) is allocated on each node, and each L2VPN/EVPN instance is represented by a local index. END.T.DT2M SID Endpoint with decapsulation and L2 table flooding Only one universal container SID (END.T.DT2M SID) is allocated on each node, and each L2VPN/EVPN instance is represented by a local index. END.T.B SID Endpoint bound to an SRv6 policy with encapsulation Only one universal container SID (END.T.B SID) is allocated on each node, and each SR policy is represented by a local index. Above the END.T.X, END.T.DX6, END.T.DX4, END.T.DT6, END.T.DT4, END.T.DT46, END.T.DX2, END.T.DX2V, END.T.DT2U, END.T.DT2M, END.T.B are all variants of the End T behavior. The END.T behavior allows the use of the next classic SRv6 SID as the key value to look up and forward in a specific IPv6 FIB table, and these variants explicitly use the next short SID of a specific length (such as 32 or 16 bits) as the key value to look-up table in the specific consumer type table . These variants can also be combined with different Flavors, such as PSP, USP and USD Flavors defined in [RFC8986]. Chen & Peng Expires 30 September 2023 [Page 4] Internet-Draft SRv6 SID Allocation March 2023 5. IANA Considerations TBD. 6. Security Considerations 7. Acknowledgements TBD. 8. Normative References [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, . [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, . [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 Email: chen.ran@zte.com.cn Shaofu Peng ZTE Email: peng.shaofu@zte.com.cn Chen & Peng Expires 30 September 2023 [Page 5]