BIER R. Chen Internet-Draft ZTE Corporation Intended status: Standards Track L. Changwang Expires: 30 July 2025 New H3C Technologies B. Xu Z. Zhang ZTE Corporation 26 January 2025 BGP extensions for BIER-TE draft-chen-bier-idr-bier-te-bgp-05 Abstract "Tree Engineering for Bit Index Explicit Replication" (BIER-TE) shares architecture and packet formats with BIER. BIER-TE forwards and replicates packets based on a BitString in the packet header, but every BitPosition of the BitString of a BIER-TE packet indicates one or more adjacencies. This document describes BGP extensions for advertising the BIER-TE specific information. 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 July 2025. Copyright Notice Copyright (c) 2025 IETF Trust and the persons identified as the document authors. All rights reserved. Chen, et al. Expires 30 July 2025 [Page 1] Internet-Draft BGP extensions for BIER-TE January 2025 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 1.1. Requirements Language . . . . . . . . . . . . . . . . . . 3 2. BIER-TE TLV . . . . . . . . . . . . . . . . . . . . . . . . . 3 2.1. The BIER-TE MPLS Encapsulation sub-TLV . . . . . . . . . 3 2.2. The BIER-TE non-MPLS Encapsulation sub-TLV . . . . . . . 4 2.3. The Bitposition sub-TLV . . . . . . . . . . . . . . . . . 5 3. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 5 4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5 4.1. The new BIER-TE TLVs . . . . . . . . . . . . . . . . . . 6 4.2. The new BIER-TE Encapsulation sub-TLVs . . . . . . . . . 6 4.3. The new Bitposition sub-TLV . . . . . . . . . . . . . . . 6 5. Security Considerations . . . . . . . . . . . . . . . . . . . 6 6. Normative References . . . . . . . . . . . . . . . . . . . . 6 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 7 1. Introduction "Tree Engineering for Bit Index Explicit Replication" (BIER-TE) shares architecture and packet formats with BIER as described in [RFC8279]. BIER-TE forwards and replicates packets based on a BitString in the packet header, but every BitPosition of the BitString of a BIER-TE packet indicates one or more adjacencies as described in [RFC9262]. This document describes BGP extensions for advertising the BIER-TE specific information. More specifically, in this document, we define a new optional, non-transitive BGP attribute, referred to as the BIER-TE attribute, to convey the BIER-TE specific information. These extensions are applicable to BGP based network scenarios. Chen, et al. Expires 30 July 2025 [Page 2] Internet-Draft BGP extensions for BIER-TE January 2025 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. BIER-TE TLV [I-D.ietf-bier-idr-extensions] defines BIER Path attribute, and this document reuse the Bier Path attribute. The content of the BIER Path attribute is one or more BIER-TE TLV as shown in Figure 1. This TLV contains BIER-TE information associated with a Prefix. 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 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | sub-domain-id | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | sub-TLVs (variable) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Type:A 2-octet field with value TBD1, see IANA Considerations section. Length: 2 octets. Subdomain-id: Unique value identifying the BIER-TE sub-domain, 1 octet. Sub-TLVs: contains one or more sub-TLV. In this document, it defines three sub-TLV: the BIER-TE MPLS Encapsulation sub-TLV , the BIER-TE non-MPLS Encapsulation sub-TLV and the Bitposition sub-TLV. 2.1. The BIER-TE MPLS Encapsulation sub-TLV This sub-TLV carries the information for the BIER MPLS encapsulation including the label range for a specific BitString length for a certain < MT,SD >. It is advertised within the BIER-TE TLV. This sub-TLV MAY appear multiple times within a single BIER-TE sub-TLV. If the same BitString length is repeated in multiple sub-TLVs inside the same BIER-TE TLV, the BIER-TE TLV MUST be ignored. Chen, et al. Expires 30 July 2025 [Page 3] Internet-Draft BGP extensions for BIER-TE January 2025 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 | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Max SI |BS Len | Label | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Type:A 2-octet field with value TBD2. Length:4 Max SI: Maximum Set Identifier (Section 1 of [RFC8279]) used in the encapsulation for this BIER subdomain for this BitString length, 1 octet. Each SI maps to a single label in the label range. The first label is for SI=0, the second label is for SI=1, etc. If the label associated with the Maximum Set Identifier exceeds the 20-bit range, the sub-sub-TLV MUST be ignored. Local BitString Length (BS Len): Encoded BitString length as per [RFC8296]. 4 bits. Label: First label of the range, 20 bits. The labels are as defined in [RFC8296]. 2.2. The BIER-TE non-MPLS Encapsulation sub-TLV The sub-TLV is advertised within the BIER-TE TLV. 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 | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Max SI |BS Len | BIFT-id | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Type:A 2-octet field with value TBD3. Length:4 Max SI: Maximum Set Identifier (Section 1 of [RFC8279]) used in the encapsulation for this BIER subdomain for this BitString length, 1 octet. The first BIFT-id is for SI=0, the second BIFT-id is for SI=1, etc. If the BIFT-id associated with the Maximum Set Identifier exceeds the 20-bit range, the sub-TLV MUST be ignored. Chen, et al. Expires 30 July 2025 [Page 4] Internet-Draft BGP extensions for BIER-TE January 2025 Local BitString Length (BS Len): Encoded BitString length as per [RFC8296]. 4 bits. BIFT-id: A 20 bit field encoding the first BIFT-id of the BIFT-id range. BIFT-id as per [I-D.ietf-bier-lsr-non-mpls-extensions]. 2.3. The Bitposition sub-TLV 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 | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | BitPosition-1 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Adjacency address-1 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ : : : : +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | BitPosition-n | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Adjacency address-n | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Type:A 2-octet field with value TBD4. Length:4 if the Nexthop is IPv4 address and 16 if the Nexthop is IPv6 address : A 2-octet field encoding the BitPosition associated with a adjacency address. Each adjacency address is a local or remote neighbor address. The Bitposition sub-TLV is included in the BIER-TE TLV. 3. Acknowledgements The authors would like to thank Zhaohui Zhang for his valuable suggestions. 4. IANA Considerations The document requests new allocations from the IANA registries as follows: Chen, et al. Expires 30 July 2025 [Page 5] Internet-Draft BGP extensions for BIER-TE January 2025 4.1. The new BIER-TE TLVs This document requests assigning code-points from the "BGP BIER Path Attribute Types" registry for the new BIER-TE TLV. Value Description Reference --------- --------------------- --------------- TBD1 BIER-TE This document 4.2. The new BIER-TE Encapsulation sub-TLVs This document requests assigning code-points from the "BGP BIER-TE TLV sub-TLV Types" for the new BIER-TE Encapsulation sub-TLVs. Value Description Reference --------- -------------------------------- --------------- TBD2 BIER-TE MPLS Encapsulation This document TBD3 BIER-TE non-MPLS Encapsulation This document 4.3. The new Bitposition sub-TLV This document requests assigning code-points from the "BGP BIER-TE TLV sub-TLV Types" for the new Bitposition sub-TLV. Value Description Reference --------- ---------------------------- --------------- TBD4 Bitposition sub-TLV This document 5. Security Considerations This document introduces no new security considerations beyond those already discussed in [RFC4271] and [RFC9262]. 6. Normative References [I-D.ietf-bier-idr-extensions] Xu, X., Chen, M., Patel, K., Wijnands, I., Przygienda, T., and Z. J. Zhang, "BGP Extensions for BIER", Work in Progress, Internet-Draft, draft-ietf-bier-idr-extensions- 19, 19 December 2024, . [I-D.ietf-bier-lsr-non-mpls-extensions] Dhanaraj, S., Yan, G., Wijnands, I., Psenak, P., Zhang, Z. J., and J. Xie, "LSR Extensions for BIER non-MPLS Chen, et al. Expires 30 July 2025 [Page 6] Internet-Draft BGP extensions for BIER-TE January 2025 Encapsulation", Work in Progress, Internet-Draft, draft- ietf-bier-lsr-non-mpls-extensions-03, 7 February 2024, . [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997, . [RFC4271] Rekhter, Y., Ed., Li, T., Ed., and S. Hares, Ed., "A Border Gateway Protocol 4 (BGP-4)", RFC 4271, DOI 10.17487/RFC4271, January 2006, . [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, May 2017, . [RFC8279] Wijnands, IJ., Ed., Rosen, E., Ed., Dolganow, A., Przygienda, T., and S. Aldrin, "Multicast Using Bit Index Explicit Replication (BIER)", RFC 8279, DOI 10.17487/RFC8279, November 2017, . [RFC8296] Wijnands, IJ., Ed., Rosen, E., Ed., Dolganow, A., Tantsura, J., Aldrin, S., and I. Meilik, "Encapsulation for Bit Index Explicit Replication (BIER) in MPLS and Non- MPLS Networks", RFC 8296, DOI 10.17487/RFC8296, January 2018, . [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, . Authors' Addresses Ran Chen ZTE Corporation Nanjing China Email: chen.ran@zte.com.cn Chen, et al. Expires 30 July 2025 [Page 7] Internet-Draft BGP extensions for BIER-TE January 2025 Changwang Lin New H3C Technologies Beijing China Email: linchangwang.04414@h3c.com Benchong Xu ZTE Corporation Nanjing China Email: xu.benchong@zte.com.cn Zheng Zhang ZTE Corporation Nanjing China Email: zhang.zheng@zte.com.cn Chen, et al. Expires 30 July 2025 [Page 8]