BIER R. Chen Internet-Draft Z. Zhang Intended status: Standards Track ZTE Corporation Expires: 6 January 2024 Y. Liu China Mobile 5 July 2023 BGP-LS extensions for BIER-TE draft-cz-bier-bgp-ls-bier-te-ext-02 Abstract 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]. 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 6 January 2024. Copyright Notice Copyright (c) 2023 IETF Trust and the persons identified as the document authors. All rights reserved. Chen, et al. Expires 6 January 2024 [Page 1] Internet-Draft BGP-LS extensions for BIER-TE July 2023 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. Requirements Language . . . . . . . . . . . . . . . . . . . . 3 3. BGP-LS Extensions for BIER-TE . . . . . . . . . . . . . . . . 3 3.1. The BIER-TE information TLV . . . . . . . . . . . . . . . 3 3.2. The MPLS Encapsulation TLV . . . . . . . . . . . . . . . 5 3.3. The non-MPLS Encapsulation TLV . . . . . . . . . . . . . 6 4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7 5. Security Considerations . . . . . . . . . . . . . . . . . . . 7 6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 7 7. Normative References . . . . . . . . . . . . . . . . . . . . 7 8. Informative references . . . . . . . . . . . . . . . . . . . 9 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 10 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 link-state routing protocols. 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 6 January 2024 [Page 2] Internet-Draft BGP-LS extensions for BIER-TE July 2023 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. 2. 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 RFC 2119 [RFC2119]. 3. BGP-LS Extensions for BIER-TE BIER-TE attributes and BitPositions associated with a link or adjacency are advertised using the BGP-LS link Attribute TLVs defined in this section and associated with the BGP-LS Link NLRI. Given that the BIER-TE informations are associated with the link or adjacency , the link Attribute TLV [RFC7752] can be used to carry the BIER-TE informations. The new Prefix Attribute TLVs are defined for the encoding of BIER-TE informations. 3.1. The BIER-TE information TLV The BIER-TE information TLV is defined to advertise the BIER-TE informations. The informations are derived from BIER-TE Info Sub-TLV of IS-IS (section 2 of [I-D.ietf-bier-te-isis]) BIER-TE sub-TLV of OSPFv2 (section 2 of [I-D.ietf-bier-te-ospf]) and OSPFv3 (section 2 of [I-D.ietf-bier-te-ospfv3]). According to different subdomain, the BIER-TE information TLV may appear multiple times. The following BIER-TE information TLV is defined: Chen, et al. Expires 6 January 2024 [Page 3] Internet-Draft BGP-LS extensions for BIER-TE July 2023 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 (TBD ) | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | sub-domain-id | BAR | IPA | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | BitPosition | EndBitPosition | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 1 Type: TBD, 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). 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 of [I-D.ietf-bier-te-isis] , section 2 of [I-D.ietf-bier-te-ospf] and [I-D.ietf-bier-te-ospfv3]. Chen, et al. Expires 6 January 2024 [Page 4] Internet-Draft BGP-LS extensions for BIER-TE July 2023 3.2. The MPLS Encapsulation TLV The 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 MPLS Encapsulation Sub-sub- TLV of IS-IS(section 3.1 of [I-D.zwx-bier-te-extensions]), MPLS Encapsulation Sub-sub-TLV of OSPFv2 and OSPFv3(section 4.1 of [I-D.zwx-bier-te-extensions]). 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 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 | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Max SI |BS Len | Label | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 2 Type: TBD, 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. 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. Chen, et al. Expires 6 January 2024 [Page 5] Internet-Draft BGP-LS extensions for BIER-TE July 2023 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. 3.3. The non-MPLS Encapsulation TLV The 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 non-MPLS Encapsulation Sub- sub-TLV of IS-IS(section 3.2 of [I-D.zwx-bier-te-extensions]), non- MPLS Encapsulation Sub-sub-TLV of OSPFv2 and OSPFv3 (section 4.2 of [I-D.zwx-bier-te-extensions]). The following the 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 | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Max SI |BS Len | BIFT-id | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 3 Type: TBD, 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. 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]. Chen, et al. Expires 6 January 2024 [Page 6] Internet-Draft BGP-LS extensions for BIER-TE July 2023 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]. 4. IANA Considerations This document requests assigning code-points from the registry for the new link Attribute TLVs. +================+========================+===============+ | TLV Code Point | Description | Value defined | +================+========================+===============+ | TBD1 | BIER-TE information | this document | +----------------+------------------------+---------------+ | TBD2 | MPLS Encapsulation | this document | +----------------+------------------------+---------------+ | TBD3 | non-MPLS Encapsulation | this document | +----------------+------------------------+---------------+ Table 1: The new link Attribute TLVs 5. 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]. 6. Acknowledgements TBD. 7. 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-01, 19 September 2022, . Chen, et al. Expires 6 January 2024 [Page 7] Internet-Draft BGP-LS extensions for BIER-TE July 2023 [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-05, 27 April 2023, . [I-D.ietf-bier-te-ospf] Chen, H., McBride, M., Wang, A., Mishra, G. S., Fan, Y., Liu, L., and X. Liu, "OSPFv2 Extensions for BIER-TE", Work in Progress, Internet-Draft, draft-ietf-bier-te-ospf-05, 27 April 2023, . [I-D.ietf-bier-te-ospfv3] Chen, H., McBride, M., Wang, A., Mishra, G. S., Fan, Y., Liu, L., and X. Liu, "OSPFv3 Extensions for BIER-TE", Work in Progress, Internet-Draft, draft-ietf-bier-te-ospfv3-05, 27 April 2023, . [I-D.zwx-bier-te-extensions] Zhang, Z., Wei, Y., Xu, B., and I. Wijnands, "IS-IS and OSPF extensions for BIER-TE (Tree Engineering for Bit Index Explicit Replication) with MPLS and non-MPLS Encapsulation", Work in Progress, Internet-Draft, draft- zwx-bier-te-extensions-02, 13 March 2023, . [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, . Chen, et al. Expires 6 January 2024 [Page 8] Internet-Draft BGP-LS extensions for BIER-TE July 2023 [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, . [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, . 8. 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 6 January 2024 [Page 9] Internet-Draft BGP-LS extensions for BIER-TE July 2023 [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 Chen, et al. Expires 6 January 2024 [Page 10]