Network Working Group H. Chen Internet-Draft M. McBride Intended status: Standards Track Futurewei Expires: 7 January 2024 A. Wang China Telecom G. Mishra Verizon Inc. Y. Fan Casa Systems L. Liu Fujitsu X. Liu Alef Edge 6 July 2023 IS-IS Extensions for BIER-TE draft-ietf-bier-te-isis-08 Abstract This document describes IS-IS extensions for distributing the BitPositions configured on a Bit-Forwarding Router (BFR) in a "Bit Index Explicit Replication Traffic Engineering" (BIER-TE) domain. Requirements Language 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] [RFC8174] when, and only when, they appear in all capitals, as shown here. 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 7 January 2024. Chen, et al. Expires 7 January 2024 [Page 1] Internet-Draft ISIS for BIER-TE July 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. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 2. Extensions to IS-IS . . . . . . . . . . . . . . . . . . . . . 3 2.1. Link BitPosition . . . . . . . . . . . . . . . . . . . . 3 2.2. Routed and Localdecap BitPositions . . . . . . . . . . . 4 3. Security Considerations . . . . . . . . . . . . . . . . . . . 5 4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5 5. References . . . . . . . . . . . . . . . . . . . . . . . . . 6 5.1. Normative References . . . . . . . . . . . . . . . . . . 6 5.2. Informative References . . . . . . . . . . . . . . . . . 7 Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 7 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 7 1. Introduction [RFC9262] introduces Bit Index Explicit Replication (BIER) Traffic/ Tree Engineering (BIER-TE). It is an architecture for per-packet stateless explicit point to multipoint (P2MP) multicast path/tree. There are three types of BitPositions (BPs) in a BIER-TE domain: link BitPosition (BP), routed BP and localdecap BP. A link BP is a BP configured on a link from Bit-Forwarding Router (BFR) X to BFR Y for a forward connected adjacency from X to Y. A routed BP is a BP configured on BFR X for a forward routed adjacency from X to a remote BFR Z not directly connected to X. A localdecap BP is a BP configured on a BFR. [RFC8401] describes IS-IS Extensions for distributing the BFR identifier (BFR-id) configured on a BFR. This document specifies IS- IS extensions for distributing the BitPositions configured a BFR in a BIER-TE domain. The BitPositions distributed may be used by a BFR as a Point of Local Repair (PLR) for Fast-ReRoute (FRR). Chen, et al. Expires 7 January 2024 [Page 2] Internet-Draft ISIS for BIER-TE July 2023 2. Extensions to IS-IS This section describes protocol extensions to IS-IS for distributing the BitPositions configured on a BFR in a BIER-TE domain. 2.1. Link BitPosition An Extended IS Reachability TLV (Type 22) defined in [RFC5305] may contain Sub-TLVs (such as those for TE) that apply to a link/ interface to a neighbor. To encode multiple links or interfaces to neighbors, the structure inside TLV is repeated. MT Intermediate Systems TLV (Type 222) defined in [RFC5120] may contain Sub-TLVs (such as those for TE) that apply to a link/ interface. It is aligned with Extended IS Reachability TLV (Type 22) beside an additional two bytes in front at the beginning of the TLV for MT-ID. Link-BP Sub-TLV of the following format is defined and used in Extended IS Reachability TLV (Type 22) and/or MT Intermediate Systems TLV (Type 222) to advertise a link BP. 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 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | BAR | IPA | sub-domain-id | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | BitPosition | DisEndBitPosition | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ ~ Sub-Sub-TLVs (variable) ~ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 1: Link-BP Sub-TLV Type: TBD1 is to be assigned by IANA. Length: Variable, dependent on Sub-Sub-TLVs. BAR, IPA and sub-domain-id: They are defined in Section 6.1 of [RFC8401]. BitPosition: A 2-octet field encoding the BitPosition locally configured on the link/interface to an Intermediate System neighbor. DisEndBitPosition: A 2-octet field encoding the BitPosition of the Chen, et al. Expires 7 January 2024 [Page 3] Internet-Draft ISIS for BIER-TE July 2023 connection on the designated Intermediate Systems (Dis) end. This field exists when the neighbor is a pseudonode. If the neighbor is not a pseudonode, this field MUST NOT exist. The DisEndBitPosition may be configured on the link/interface to a transit network (i.e., broadcast link or say LAN) as described in [I-D.chen-bier-te-lan]. No Sub-Sub-TLVs are currently defined. 2.2. Routed and Localdecap BitPositions A Sub-TLV, called Node BPs Sub-TLV, is defined and carried within the TLVs 235, 237 [RFC5120], 135 [RFC5305], or 236 [RFC5308]. It contains Sub-Sub-TLVs. Two types of Sub-Sub-TLVs are defined. One is for a Routed BitPosition and the other for a Localdecap BitPosition. The Node BPs Sub-TLV has the following format: 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 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | BAR | IPA | sub-domain-id | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Sub-Sub-TLVs ~ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 2: Node BPs Sub-TLV Type: TBD2 is to be assigned by IANA. Length: Variable. BAR, IPA and sub-domain-id: They are defined in Section 6.1 of [RFC8401]. Sub-Sub-TLVs: They are Routed-BP Sub-Sub-TLVs for Routed BPs and/or Localdecap-BP Sub-Sub-TLV for Localdecap BP. The Routed-BP Sub-Sub-TLV has the following format: 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 (1) | Length(4) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | BitPosition | BFR-id | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Chen, et al. Expires 7 January 2024 [Page 4] Internet-Draft ISIS for BIER-TE July 2023 Figure 3: Routed-BP Sub-Sub-TLV Type: 1 is the type for routed BP. Length: It is 4. BitPosition: A 2-octet field encoding the BitPosition configured on a BFR for a forward routed adjacency to a remote BFR. BFR-id: A 2-octet field encoding the BFR-id of the remote BFR. The Localdecap-BP Sub-Sub-TLV has the following format: 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 (2) | Length(2) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | BitPosition | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 4: Localdecap-BP Sub-Sub-TLV Type: 2 is the type for localdecap BP. Length: It is 2. BitPosition: A 2-octet field encoding the localdecap BitPosition configured on a BFR. 3. Security Considerations Protocol extensions defined in this document do not affect the IS-IS security. 4. IANA Considerations Under "IS-IS Sub-TLVs for TLVs Advertising Neighbor Information" registry, IANA is requested to assign a new Sub-TLV Type for Link BP as follows: +=======+=============+==+==+==+===+===+===+=============+ | Type |Description |22|23|25|141|222|223|reference | +=======+=============+==+==+==+===+===+===+=============+ | TBD1 | Link BP |y |y |n | n | y | y |This document| +-------+-------------+--+--+--+---+---+---+-------------+ Chen, et al. Expires 7 January 2024 [Page 5] Internet-Draft ISIS for BIER-TE July 2023 Under "IS-IS Sub-TLVs for TLVs Advertising Prefix Reachability" registry, IANA is requested to assign a new Sub-TLV Type for Node BPs as follows: +=======+=============+==+===+===+===+===+=============+ | Type |Description |27|135|235|236|237|reference | +=======+=============+==+===+===+===+===+=============+ | TBD2 | Node BPs |n | y | y | y | y |This document| +-------+-------------+--+---+---+---+---+-------------+ IANA is requested to create a new sub-registry "Sub-Sub-TLVs for Node BPs Sub-TLV" as follows: +==============+===================+=====================+ | Type | Name | reference | +==============+===================+=====================+ | 0 | Reserved | +--------------+-------------------+---------------------+ | 1 | Routed BP | This document | +--------------+-------------------+---------------------+ | 2 | Localdecap BP | This document | +--------------+-------------------+---------------------+ | 3 - 255 | Unassigned | +--------------+-------------------+---------------------+ 5. References 5.1. 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, . [RFC5120] Przygienda, T., Shen, N., and N. Sheth, "M-ISIS: Multi Topology (MT) Routing in Intermediate System to Intermediate Systems (IS-ISs)", RFC 5120, DOI 10.17487/RFC5120, February 2008, . [RFC5305] Li, T. and H. Smit, "IS-IS Extensions for Traffic Engineering", RFC 5305, DOI 10.17487/RFC5305, October 2008, . [RFC5308] Hopps, C., "Routing IPv6 with IS-IS", RFC 5308, DOI 10.17487/RFC5308, October 2008, . Chen, et al. Expires 7 January 2024 [Page 6] Internet-Draft ISIS for BIER-TE July 2023 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, May 2017, . [RFC9262] Eckert, T., Ed., Menth, M., and G. Cauchie, "Tree Engineering for Bit Index Explicit Replication (BIER-TE)", RFC 9262, DOI 10.17487/RFC9262, October 2022, . 5.2. Informative References [I-D.chen-bier-te-lan] Chen, H., McBride, M., Wang, A., Mishra, G. S., Liu, L., and X. Liu, "BIER-TE for Broadcast Link", Work in Progress, Internet-Draft, draft-chen-bier-te-lan-06, 9 March 2023, . [RFC8401] Ginsberg, L., Ed., Przygienda, T., Aldrin, S., and Z. Zhang, "Bit Index Explicit Replication (BIER) Support via IS-IS", RFC 8401, DOI 10.17487/RFC8401, June 2018, . Acknowledgments The authors would like to thank Acee Lindem, Les Ginsberg, Tony Przygienda, Jeffrey Zhang and Toerless Eckert for their comments on this work. Authors' Addresses Huaimo Chen Futurewei Boston, MA, United States of America Email: Huaimo.chen@futurewei.com Mike McBride Futurewei Email: michael.mcbride@futurewei.com Chen, et al. Expires 7 January 2024 [Page 7] Internet-Draft ISIS for BIER-TE July 2023 Aijun Wang China Telecom Beiqijia Town, Changping District Beijing 102209 China Email: wangaj3@chinatelecom.cn Gyan S. Mishra Verizon Inc. 13101 Columbia Pike Silver Spring, MD 20904 United States of America Phone: 301 502-1347 Email: gyan.s.mishra@verizon.com Yanhe Fan Casa Systems United States of America Email: yfan@casa-systems.com Lei Liu Fujitsu United States of America Email: liulei.kddi@gmail.com Xufeng Liu Alef Edge United States of America Email: xufeng.liu.ietf@gmail.com Chen, et al. Expires 7 January 2024 [Page 8]