Networking Working Group R. Chen Internet-Draft Zh. Zhang Intended status: Standards Track ZTE Corporation Expires: February 5, 2022 August 4, 2021 BGP Link-State extensions for BIER-TE draft-cz-bier-bgp-ls-bier-te-ext-00 Abstract 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 [I-D.ietf-bier-te-arch]. 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 February 5, 2022. Copyright Notice Copyright (c) 2021 IETF Trust and the persons identified as the document authors. All rights reserved. Chen & Zhang Expires February 5, 2022 [Page 1] Internet-Draft BGP-LS extensions for BIER-TE August 2021 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 Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 2. Conventions used in this document . . . . . . . . . . . . . . 3 3. BGP-LS Extensions for BIER-TE . . . . . . . . . . . . . . . . 3 3.1. The new Link Attribute TLV . . . . . . . . . . . . . . . 3 4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4 5. Security Considerations . . . . . . . . . . . . . . . . . . . 5 6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 5 7. References . . . . . . . . . . . . . . . . . . . . . . . . . 5 7.1. Normative references . . . . . . . . . . . . . . . . . . 5 7.2. Informative references . . . . . . . . . . . . . . . . . 6 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 6 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 [[I-D.ietf-bier-te-arch]]. 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. 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 Chen & Zhang Expires February 5, 2022 [Page 2] Internet-Draft BGP-LS extensions for BIER-TE August 2021 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. 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. 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 TLV defined in this section and associated with the BGP-LS Link NLRI. 3.1. The new Link Attribute 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.chen-bier-te-isis]]) BIER-TE sub-TLV of OSPFv2 (section 2 of [[I-D.chen-bier-te-ospf]]) and OSPFv3 (section 2 of [[I-D.chen-bier-te-ospfv3]]). According to different subdomain, the BIER-TE information TLV may appear multiple times. The BIER-TE information 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 (TBD1) | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | sub-domain-id | MT-ID | BAR | IPA | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | BitPosition | EndBitPosition | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 1: The BIER-TE information TLV 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. Chen & Zhang Expires February 5, 2022 [Page 3] Internet-Draft BGP-LS extensions for BIER-TE August 2021 MT-ID: Multi-Topology ID that identifies the topology that is associated with 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). For ISIS, this field is valid when the neighbor is a pseudonode. If the neighbor is not a pseudonode, this field MUST be ignored. For OSPFv2 and OSPFv3, this field is valid when the Link Type in the Router-Link TLV containing this Sub-TLV is 2 (i.e., Transit Network or LAN) and for the other value of the Link Type, this field MUST be ignored. The EndBitPosition may be configured on the link/interface to a transit network (i.e., broadcast link or say LAN). If the MT-ID value is outside of the values specified in [RFC4915], the BIER-TE information Sub-TLV MUST be ignored. 4. IANA Considerations This document requests assigning code-points from the registry for the new Link Attribute TLV. +-------------------+-----------------------------+-----------------+ | TLV Code Point | Description | Value defined | +-------------------+-----------------------------+-----------------+ | TBD1 | BIER-TE information | this document | +-------------------+-----------------------------+-----------------+ Table 1: The new Link Attribute TLV Chen & Zhang Expires February 5, 2022 [Page 4] Internet-Draft BGP-LS extensions for BIER-TE August 2021 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. References 7.1. Normative references [I-D.chen-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", draft-chen-bier-te-isis-01 (work in progress), July 2021. [I-D.chen-bier-te-ospf] Chen, H., McBride, M., Wang, A., Mishra, G. S., Fan, Y., Liu, L., and X. Liu, "OSPF Extensions for BIER-TE", draft- chen-bier-te-ospf-02 (work in progress), July 2021. [I-D.chen-bier-te-ospfv3] Chen, H., McBride, M., Wang, A., Mishra, G. S., Fan, Y., Liu, L., and X. Liu, "OSPFv3 Extensions for BIER-TE", draft-chen-bier-te-ospfv3-02 (work in progress), July 2021. [I-D.ietf-bier-te-arch] Eckert, T., Cauchie, G., and M. Menth, "Tree Engineering for Bit Index Explicit Replication (BIER-TE)", draft-ietf- bier-te-arch-10 (work in progress), July 2021. [RFC4655] Farrel, A., Vasseur, J., 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 & Zhang Expires February 5, 2022 [Page 5] Internet-Draft BGP-LS extensions for BIER-TE August 2021 [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, . [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, . 7.2. 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, . [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 Chen & Zhang Expires February 5, 2022 [Page 6] Internet-Draft BGP-LS extensions for BIER-TE August 2021 Ran Chen ZTE Corporation No.50 Software Avenue,Yuhuatai District Nanjing, Jiangsu Province 210012 China Phone: +86 025 88014636 Email: chen.ran@zte.com.cn Zheng Zhang ZTE Corporation No.50 Software Avenue,Yuhuatai District Nanjing, Jiangsu Province 210012 China Email: zhang.zheng@zte.com.cn Chen & Zhang Expires February 5, 2022 [Page 7]