BIER R. Chen Internet-Draft Z. Zhang Intended status: Standards Track ZTE Corporation Expires: 15 April 2025 Y. Liu China Mobile L. Changwang New H3C Technologies 12 October 2024 BGP-LS extensions for BIER-TE draft-cz-bier-bgp-ls-bier-te-ext-04 Abstract 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. BGP Link-State (BGP-LS) enables the collection of various topology informations from the network, and the topology informations are used by the PCE to calculate the path and then propagate them onto the BFRs(instead of having each node to calculate on its own) and that can be for both inter-as and intra-as situations. This document specifies extensions to the BGP Link-state address- family in order to advertise BIER-TE informations. 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 15 April 2025. Chen, et al. Expires 15 April 2025 [Page 1] Internet-Draft BGP-LS extensions for BIER-TE October 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. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1.1. Requirements Language . . . . . . . . . . . . . . . . . . 3 2. BGP-LS Extensions for BIER-TE . . . . . . . . . . . . . . . . 3 2.1. Link Attribute TLV . . . . . . . . . . . . . . . . . . . 3 2.1.1. The Link-BP TLV . . . . . . . . . . . . . . . . . . . 4 2.2. Node Attributes TLVs . . . . . . . . . . . . . . . . . . 5 2.2.1. The Routed-BP TLV . . . . . . . . . . . . . . . . . . 5 2.2.2. The Localdecap-BP TLV . . . . . . . . . . . . . . . . 6 2.2.3. BIER-TE MPLS Encapsulation TLV . . . . . . . . . . . 7 2.2.4. BIER-TE Non-MPLS Encapsulation TLV . . . . . . . . . 8 3. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9 4. Security Considerations . . . . . . . . . . . . . . . . . . . 9 5. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 10 6. Normative References . . . . . . . . . . . . . . . . . . . . 10 7. Informative references . . . . . . . . . . . . . . . . . . . 11 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 12 1. Introduction 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]. When BIER-TE is enabled in an IGP domain, BIER-TE-related informations will be advertised via IGP. The flooding scope for the IGP extensions for BIER-TE is IGP area-wide. by using the IGP alone it is not enough to construct across multiple IGP Area. Chen, et al. Expires 15 April 2025 [Page 2] Internet-Draft BGP-LS extensions for BIER-TE October 2024 The BGP-LS address-family/sub-address-family have been defined to allow BGP to carry Link-State informations. This document specifies extensions to the BGP Link-state address-family in order to advertise BIER-TE-specific informations, Similar to BGP-LS Advertisement of IGP Traffic Engineering Performance Metric Extensions([RFC8571]). An external component (e.g., a controller/a PCE(see [RFC4655] for PCE- Based Architecture , [RFC5440] for PCEP and [RFC5376] for Inter-AS Requirements for the PCEP.))then can learn the BIER-TE informations in the "northbound" direction and calculate BIER-TE Path and then propagate them onto BFRs (instead of having each BFR to calculate on its own), and that can be for both inter-as and intra-as situations. 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. BGP-LS Extensions for BIER-TE [I-D.ietf-bier-te-ospf] and [I-D.ietf-bier-te-isis] specifies IGP extensions for distributing the BitPositions configured on a BFR with MPLS and Non-MPLS encapsulation for BIER-TE in a BIER-TE domain. and then external component (e.g., a controller) need to collect the BitPositions configured on a BFR with MPLS and Non-MPLS encapsulation for BIER-TE in the "northbound" direction within the BIER-TE domain. 2.1. Link Attribute TLV The following Link Attribute TLV is defined: +======+=============================+=============+ | Type | Description | Section | +======+=============================+=============+ | TBD1 | Link-BP | section 3.2 | +------+-----------------------------+-------------+ Chen, et al. Expires 15 April 2025 [Page 3] Internet-Draft BGP-LS extensions for BIER-TE October 2024 2.1.1. The Link-BP TLV The Link-BP TLV is defined to advertise a link BitPosition (BP). The informations are derived from Link-BP Sub-TLV of IS-IS (section 2.1 of [I-D.ietf-bier-te-isis]) and OSPF (section 2.1 of [I-D.ietf-bier-te-ospf]). According to different subdomain, the Link-BP TLV may appear multiple times. The following Link-BP TLV is defined: 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 | BAR | IPA | Reserved | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | BitPosition | EndBitPosition | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Type: TBD1, see IANA Considerations section. Length: 2 octets. Subdomain-id: Unique value identifying the BIER-TE sub-domain, 1 octet. BAR: A 1-octet field encoding the BIER Algorithm, used to calculate underlay paths to reach BFERs. Values are allocated from the "BIER Algorithms" registry which is defined in [RFC8401]. IPA: A 1-octet field encoding the IGP Algorithm, used to either modify,enhance, or replace the calculation of underlay paths to reach BFERs as defined by the BAR value. Values are from the IGP Algorithm registry. BitPosition: A 2-octet field encoding the BitPosition locally configured on the link/interface when the Link Type of the link in the Router-Link TLV containing this Sub-TLV is 1 (i.e., Point-to- Point connection to another router) or 2 (i.e., connection to Transit Network or say LAN). Chen, et al. Expires 15 April 2025 [Page 4] Internet-Draft BGP-LS extensions for BIER-TE October 2024 EndBitPosition: A 2-octet field encoding the BitPosition of the connection on the designated Intermediate Systems (Dis) end (ISIS) / designated router (DR) end( OSPFv2 and OSPFv3), as defined in section 2.1 of [I-D.ietf-bier-te-isis] , section 2.1 of [I-D.ietf-bier-te-ospf]. 2.2. Node Attributes TLVs The following Node Attribute TLVs are defined: +======+================================+=============+ | Type | Description | Section | +======+================================+=============+ | TBD2 | Routed-BP | section 3.3 | +------+--------------------------------+-------------+ | TBD3 | Localdecap-BP | section 3.4 | +------+--------------------------------+-------------+ | TBD4 | BIER-TE MPLS Encapsulation | section 3.3 | +------+--------------------------------+-------------+ | TBD5 | BIER-TE Non-MPLS Encapsulation | section 3.4 | +------+--------------------------------+-------------+ 2.2.1. The Routed-BP TLV The Routed-BP TLV is defined to advertise a forward routed BitPosition (BP). The informations are derived from Node BPs TLV and Routed-BP Sub-TLV of IS-IS (section 2.1 of [I-D.ietf-bier-te-isis]) and OSPF (section 2.1 of [I-D.ietf-bier-te-ospf]). According to different subdomain, the Routed-BP TLV may appear multiple times. The following Routed-BP TLV is defined: 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 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | sub-domain-id | BAR | IPA | Reserved | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | BitPosition | BFR-id | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Chen, et al. Expires 15 April 2025 [Page 5] Internet-Draft BGP-LS extensions for BIER-TE October 2024 Type: TBD2, see IANA Considerations section. Length: 2 octets. Subdomain-id: Unique value identifying the BIER-TE sub-domain, 1 octet. BAR: A 1-octet field encoding the BIER Algorithm, used to calculate underlay paths to reach BFERs. Values are allocated from the "BIER Algorithms" registry which is defined in [RFC8401]. IPA: A 1-octet field encoding the IGP Algorithm, used to either modify,enhance, or replace the calculation of underlay paths to reach BFERs as defined by the BAR value. Values are from the IGP Algorithm registry. 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. 2.2.2. The Localdecap-BP TLV The Localdecap-BP TLV is defined to advertise a localdecap BitPosition (BP). The informations are derived from Node BPs TLV and Localdecap-BP Sub-TLV of IS-IS (section 2.1 of [I-D.ietf-bier-te-isis]) and OSPF (section 2.1 of [I-D.ietf-bier-te-ospf]). According to different subdomain, the Routed-BP TLV may appear multiple times. The following Localdecap-BP TLV is defined: 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 (TBD3) | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | sub-domain-id | BAR | IPA | Reserved | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | BitPosition | Reserved | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Chen, et al. Expires 15 April 2025 [Page 6] Internet-Draft BGP-LS extensions for BIER-TE October 2024 Type: TBD3, see IANA Considerations section. Length: 2 octets. Subdomain-id: Unique value identifying the BIER-TE sub-domain, 1 octet. BAR: A 1-octet field encoding the BIER Algorithm, used to calculate underlay paths to reach BFERs. Values are allocated from the "BIER Algorithms" registry which is defined in [RFC8401]. IPA: A 1-octet field encoding the IGP Algorithm, used to either modify,enhance, or replace the calculation of underlay paths to reach BFERs as defined by the BAR value. Values are from the IGP Algorithm registry. BitPosition: A 2-octet field encoding the localdecap BitPosition configured on a BFR. 2.2.3. BIER-TE MPLS Encapsulation TLV The BIER-TE MPLS Encapsulation TLV is used in order to advertise MPLS specific informations used for BIER-TE. It MAY appear multiple times. The informations are derived from BIER-TE MPLS Encapsulation Sub-TLV of OSPF (section 2.3.1 of [I-D.ietf-bier-te-ospf]). In some environment, each router allocates its labels, and advertises it to the controller.That solution is simpler as the controller does not need to deal with label allocation. If the controller has to deal with Label allocation , there needs to be a (global) range carved out such there are no conflicts. We can avoid all that by having the router allocate the BIER Label range and advertise it to the controller. The following the BIER-TE MPLS Encapsulation TLV is defined: 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 (TBD4) | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Max SI |BS Len | Label | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Type: TBD4, see IANA Considerations section. Chen, et al. Expires 15 April 2025 [Page 7] Internet-Draft BGP-LS extensions for BIER-TE October 2024 Length: 4. Max SI: A 1-octet field encoding the maximum Set Identifier(as defined in [RFC8279]), used in the encapsulation for this BIER subdomain for this BitString length. BS Len: A 4-bit field field encoding the Bitstring length as per [RFC8296]. Label: First label of the range, 20 bits. The labels are as defined [RFC8296]. The 4 leftmost bits MUST be ignored. BS length in multiple MPLS Encapsulation TLV associated with the same BIER-TE information TLV MUST NOT repeat, otherwise only the first MPLS Encapsulation TLV with such BS length MUST be used and any subsequent MPLS Encapsulation TLVs with the same BS length MUST be ignored. 2.2.4. BIER-TE Non-MPLS Encapsulation TLV The BIER-TE Non-MPLS Encapsulation TLV is used in order to advertise Non-MPLS encapsulation(e.g. ethernet encapsulation ) capability and other associated parameters of the encapsulation. It MAY appear multiple times. The informations are derived from BIER-TE Non-MPLS Encapsulation Sub-TLV of OSPF (section 2.3.2 of [I-D.ietf-bier-te-ospf]). The following the BIER-TE Non-MPLS Encapsulation TLV is defined: 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 (TBD5) | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Max SI |BS Len | BIFT-id | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Type: TBD5, see IANA Considerations section. Length: 4. Max SI:A 1-octet field encoding the maximum Set Identifier(as defined in [RFC8279]), used in the encapsulation for this BIER subdomain for this BitString length. Chen, et al. Expires 15 April 2025 [Page 8] Internet-Draft BGP-LS extensions for BIER-TE October 2024 The "BIFT-id range" is the set of 20-bit values beginning with the BIFT-id and ending with (BIFT-id + (Max SI)). A unique BIFT-id range is allocated for each BitString length and sub-domain-id. These BIFT-id's are used for BIER forwarding as described in [RFC8279])and [RFC8296]. Local BitString Length (BS Len): A 4-bit field encoding the Bitstring length as per [RFC8296]. BIFT-id:A 20bit field encoding the first BIFT-id of the BIFT-id range. The BIER-id are as defined in [I-D.ietf-bier-lsr-non-mpls-extensions]. 3. IANA Considerations IANA maintains a registry group called "BGP-LS NLRI and Attribute TLVs" in the "Border Gateway Protocol - Link State (BGP-LS) Parameters" registry group. The following TLV codepoints are suggested (for early allocation by IANA): +============+================================+==================+ | Code Point | Description | Value defined in | +============+================================+==================+ | TBD1 | Link-BP | this document | +------------+--------------------------------+------------------+ | TBD2 | Routed-BP | this document | +------------+--------------------------------+------------------+ | TBD3 | Localdecap-BP | this document | +------------+--------------------------------+------------------+ | TBD4 | BIER-TE MPLS Encapsulation | this document | +------------+--------------------------------+------------------+ | TBD5 | BIER-TE Non-MPLS Encapsulation | this document | +------------+--------------------------------+------------------+ 4. Security Considerations Procedures and protocol extensions defined in this document do not affect the BGP security model. See the "Security Considerations"section of [RFC4271] for a discussion of BGP security. Security considerations for acquiring and distributing BGP-LS information are discussed in [RFC7752]. Chen, et al. Expires 15 April 2025 [Page 9] Internet-Draft BGP-LS extensions for BIER-TE October 2024 5. Acknowledgements TBD. 6. Normative References [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 Encapsulation", Work in Progress, Internet-Draft, draft- ietf-bier-lsr-non-mpls-extensions-03, 7 February 2024, . [I-D.ietf-bier-te-isis] Chen, H., McBride, M., Wang, A., Mishra, G. S., Fan, Y., Liu, L., and X. Liu, "IS-IS Extensions for BIER-TE", Work in Progress, Internet-Draft, draft-ietf-bier-te-isis-10, 28 March 2024, . [I-D.ietf-bier-te-ospf] Chen, H., McBride, M., Zhang, Z., Wang, A., Mishra, G. S., and Y. Fan, "OSPF Extensions for BIER-TE", Work in Progress, Internet-Draft, draft-ietf-bier-te-ospf-10, 1 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, . [RFC4655] Farrel, A., Vasseur, J.-P., and J. Ash, "A Path Computation Element (PCE)-Based Architecture", RFC 4655, DOI 10.17487/RFC4655, August 2006, . [RFC4915] Psenak, P., Mirtorabi, S., Roy, A., Nguyen, L., and P. Pillay-Esnault, "Multi-Topology (MT) Routing in OSPF", RFC 4915, DOI 10.17487/RFC4915, June 2007, . [RFC7752] Gredler, H., Ed., Medved, J., Previdi, S., Farrel, A., and S. Ray, "North-Bound Distribution of Link-State and Traffic Engineering (TE) Information Using BGP", RFC 7752, DOI 10.17487/RFC7752, March 2016, . Chen, et al. Expires 15 April 2025 [Page 10] Internet-Draft BGP-LS extensions for BIER-TE October 2024 [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, . [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, . [RFC8571] Ginsberg, L., Ed., Previdi, S., Wu, Q., Tantsura, J., and C. Filsfils, "BGP - Link State (BGP-LS) Advertisement of IGP Traffic Engineering Performance Metric Extensions", RFC 8571, DOI 10.17487/RFC8571, March 2019, . [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, . 7. Informative references [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, . [RFC5376] Bitar, N., Zhang, R., and K. Kumaki, "Inter-AS Requirements for the Path Computation Element Communication Protocol (PCECP)", RFC 5376, DOI 10.17487/RFC5376, November 2008, . Chen, et al. Expires 15 April 2025 [Page 11] Internet-Draft BGP-LS extensions for BIER-TE October 2024 [RFC5440] Vasseur, JP., Ed. and JL. Le Roux, Ed., "Path Computation Element (PCE) Communication Protocol (PCEP)", RFC 5440, DOI 10.17487/RFC5440, March 2009, . Authors' Addresses Ran Chen ZTE Corporation Nanjing China Email: chen.ran@zte.com.cn Zheng Zhang ZTE Corporation Nanjing China Email: zhang.zheng@zte.com.cn Yisong Liu China Mobile Beijing China Email: liuyisong@chinamobile.com Changwang Lin New H3C Technologies Beijing China Email: linchangwang.04414@h3c.com Chen, et al. Expires 15 April 2025 [Page 12]