LSR Working Group L. Gong Internet Draft China Mobile Intended status: Standards Track C. Lin Expires: April 28, 2025 M. Chen New H3C Technologies K. Talaulikar L. Ginsberg P. Psenak Cisco Systems October 19, 2024 Advertisement of Remote Interface Identifiers for Layer 2 Bundle Members draft-glctgp-lsr-l2-bundle-member-remote-id-01 Abstract In networks where Layer 2 (L2) interface bundles (such as a Link Aggregation Group (LAG) [IEEE802.1AX]) are deployed, a controller may need to collect the connectivity relationships between bundle members for traffic engineering (TE) purposes. For example, when performing topology management and bidirectional path computation for TE, it is essential to know the connectivity relationships among bundle members. This document describes how OSPF and IS-IS would advertise the remote interface identifiers for Layer 2 bundle members. The corresponding extension of BGP-LS is also specified. 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 28 April 2025. Glctgp, et al. Expire April 28, 2025 [Page 1] Internet-Draft L2 Bundle Member Remote ID 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. Use Case.......................................................3 3. Advertising L2 Bundle Member Remote Interface Identifier.......4 4. OSPF Extension.................................................5 5. IS-IS Extension................................................5 6. BGP-LS Extension...............................................6 7. Acquirement of Remote Interface Identifier.....................7 8. Security Considerations........................................7 9. IANA Considerations............................................7 10. References....................................................8 10.1. Normative References.....................................8 10.2. Informational References.................................9 Authors' Addresses................................................9 1. Introduction BGP-LS [RFC9552] is widely used for collecting topology information from IGPs. In networks where Layer 2 (L2) interface bundles (such as a Link Aggregation Group (LAG) [IEEE802.1AX]) are deployed, a controller may need to collect the connectivity relationships between bundle members for traffic engineering (TE) purposes. For example, when performing topology management and bidirectional path computation for TE, it is essential to know the connectivity relationships among bundle members. When advertising L2 bundles in OSPF [RFC9356] and IS-IS [RFC8668], a member link is described by its local interface identifier, also referred to as a link local identifier. If the remote interface identifier could be advertised for each member link, the pairing Glctgp, et al. Expires April 15, 2025 [Page 2] Internet-Draft L2 Bundle Member Remote ID October 2024 relationships between the local and remote interfaces would be clear. This document describes the mechanism for advertising the remote interface identifier for Layer 2 bundle members in OSPF and IS-IS. The BGP-LS extension for advertising L2 bundle member interface remote identifier is also specified in this document. 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. Use Case Figure 1 shows a network, in which an L2 bundle is deployed between R1 and R2. The controller collects the topology information from R3 via BGP-LS. +----------+ BGP-LS |Controller|<******************** +----------+ * * * * +----+ L2-Bundle +----+ +----+ | | /-------member 1-------\ | | | | | | / \ | | | | | R1 +----------member 2----------+ R2 +---+ R3 + | | \ / | | | | | | \-------member 3-------/ | | | | +----+ +----+ +----+ Figure 1 The network operator may want to control bidirectional traffic flows on the individual member links of the underlying Layer 2 bundle for TE purposes. The real-time bandwidth, delay, and link loss might be measured for each bundle member at both ends. Labels or SIDs might be allocated for each bundle member at both ends. So, there would be requirements for the controller to figure out the connectivity relationships between bundle members. This document defines a mechanism for IGP routers to advertise the remote interface identifiers for each L2 bundle member, along with Glctgp, et al. Expires April 15, 2025 [Page 3] Internet-Draft L2 Bundle Member Remote ID October 2024 the corresponding mechanism for the controller to collect such information via BGP-LS. 3. Advertising L2 Bundle Member Remote Interface Identifier In OSPF, the remote interface identifiers of L2 bundle members are advertised as follows. OSPFv2 Extended Link TLV, or OSPFv3 Router-Link TLV, for L3 Link: L2 Bundle Member Attributes TLV: L2 Bundle Member Descriptor of Member #1 L2 Bundle Member Interface Remote Identifier Sub-TLV (Optional - as defined in Section 4) L2 Bundle Member Attributes TLV: L2 Bundle Member Descriptor of Member #2 L2 Bundle Member Interface Remote Identifier Sub-TLV (Optional - as defined in Section 4) ... L2 Bundle Member Attributes TLV: L2 Bundle Member Descriptor of Member #n L2 Bundle Member Interface Remote Identifier Sub-TLV (Optional - as defined in Section 4) In IS-IS, the remote interface identifiers of L2 bundle members are advertised as follows. Note that IS-IS can advertise a set of members in a single L2 Bundle Member Attribute Descriptor, so the L2 Bundle Member Interface Remote Identifier Sub-TLV MUST carry multiple remote interface identifiers, one for each of the bundle members advertised in the associated L2 Bundle Member Descriptor. L2 Bundle Member Attributes TLV: Parent L3 Neighbor Descriptor Length of L2 Bundle Attribute Descriptor Number of L2 Bundle Member Descriptors L2 Bundle Member Link Local Identifiers of Member #1,#2,...,#n Sub-TLV(s) L2 Bundle Member Interface Remote Identifier Sub-TLV (Optional - as defined in Section 5) for Member #1,#2,...,#n In BGP-LS, the remote interface identifiers of L2 bundle members are advertised as follows. Glctgp, et al. Expires April 15, 2025 [Page 4] Internet-Draft L2 Bundle Member Remote ID October 2024 NLRI for L3 Link R1->R2 Attributes: L2 Bundle Member Attributes TLV: L2 Bundle Member Descriptor of Member #1 L2 Bundle Member Interface Remote Identifier Sub-TLV (Optional - as defined in Section 6) L2 Bundle Member Attributes TLV: L2 Bundle Member Descriptor of Member #2 L2 Bundle Member Interface Remote Identifier Sub-TLV (Optional - as defined in Section 6) ... L2 Bundle Member Attributes TLV: L2 Bundle Member Descriptor of Member #n L2 Bundle Member Interface Remote Identifier Sub-TLV (Optional - as defined in Section 6) 4. OSPF Extension This document defines a new L2 Bundle Member Interface Remote Identifier Sub-TLV in both OSPFv2 and OSPFv3. This Sub-TLV is used to advertise the remote interface identifier for a L2 bundle member. It can be carried as a sub-TLV of the OSPF L2 Bundle Member Attributes TLV [RFC9356]. It 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 (TBA) | Length (4) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Remote Interface ID | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ o Type: TBA. o Length: 4. o Remote Interface ID: Remote identifier of interface, 4 octets. A remote interface ID with value of zero is not valid and MUST be ignored and handled as if the sub-TLV was not present. 5. IS-IS Extension This document defines a new L2 Bundle Member Interface Remote Identifier Sub-TLV in IS-IS. This Sub-TLV is used to advertise the remote interface identifiers for L2 bundle members. Glctgp, et al. Expires April 15, 2025 [Page 5] Internet-Draft L2 Bundle Member Remote ID October 2024 It can be carried as a sub-TLV of the IS-IS L2 Bundle Member Attributes TLV [RFC8668]. It 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 (TBA) | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Remote Interface ID 1 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ ~ ... ~ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Remote Interface ID N | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ o Type: TBA. o Length: 4 * Number of L2 Bundle Member Descriptors. o Remote Interface ID: Remote identifier of interface, 4 octets. There MUST be one Remote Interface ID for each of the L2 Bundle Members advertised under the associated L2 Bundle Member Attribute Descriptor. A remote interface ID with value of zero MUST be ignored and handled as if the value was unknown. 6. BGP-LS Extension This document defines a new L2 Bundle Member Interface Remote Identifier Sub-TLV in BGP-LS. This Sub-TLV is derived from the Remote Interface Identifier Sub-TLV of OSPF (Section 3) and IS-IS (Section 4). It can be carried as a sub-TLV of the BGP-LS L2 Bundle Member Attributes TLV [RFC9085]. It 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 (TBA) | Length (4) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Remote Interface ID | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ o Type: TBA. o Length: 4. Glctgp, et al. Expires April 15, 2025 [Page 6] Internet-Draft L2 Bundle Member Remote ID October 2024 o Remote Interface ID: Remote identifier of interface, 4 octets. A remote interface ID with value of zero is not valid and MUST be ignored and handled as if the sub-TLV was not present. 7. Acquirement of Remote Interface Identifier IGPs have no direct way to exchange L2 bundle member link identifiers since the Layer 3 protocol is not operating directly on the bundle members. Some L2 protocols may be used to get the remote interface identifiers for bundle members. This may be discovered via [IEEE802.1AX] when used to form the LAG bundle. A router may also run LLDP [802.1AB] on the bundle members to exchange local interface identifiers with its neighbor, by using the LLDP Management Address TLV. How the remote interface identifier is obtained is out of the scope of this document. 8. Security Considerations TBD. 9. IANA Considerations This document adds the following new sub-TLV to the "OSPFv2 Extended Link TLV Sub-TLVs" registry. +------+----------------------------------------------+----+ | Type | Designation |L2BM| +======+==============================================+====+ | TBA | L2 Bundle Member Interface Remote Identifier | Y | +------+----------------------------------------------+----+ This document adds the following new sub-TLV to the "OSPFv3 Extended-LSA Sub-TLVs" registry. +------+----------------------------------------------+----+ | Type | Description |L2BM| +======+==============================================+====+ | TBA | L2 Bundle Member Interface Remote Identifier | Y | +------+----------------------------------------------+----+ This document adds the following new sub-TLV to the "IS-IS Sub-TLVs for TLVs Advertising Neighbor Information" registry. Glctgp, et al. Expires April 15, 2025 [Page 7] Internet-Draft L2 Bundle Member Remote ID October 2024 +------+-----------------------------+---+---+---+---+---+---+ | Type | Description | 22| 23| 25|141|222|223| +======+=============================+===+===+===+===+===+===+ | TBA | L2 Bundle Member | n | n | y | n | n | n | | | Interface Remote Identifier | | | | | | | +------+-----------------------------+---+---+---+---+---+---+ This document adds the following new sub-TLV to the "BGP-LS NLRI and Attribute TLVs" registry. +------+----------------------------------------------+ | Type | Description | +======+==============================================+ | TBA | L2 Bundle Member Interface Remote Identifier | +------+----------------------------------------------+ 10. References 10.1. Normative References [IEEE802.1AX] IEEE, "IEEE Standard for Local and Metropolitan Area Networks--Link Aggregation", IEEE Std 802.1AX, DOI 10.1109/IEEESTD.2020.9105034, May 2020, . [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, May 2017 [RFC8668] Ginsberg, L., Ed., Bashandy, A., Filsfils, C., Nanduri, M., and E. Aries, "Advertising Layer 2 Bundle Member Link Attributes in IS-IS", RFC 8668, DOI 10.17487/RFC8668, December 2019, . [RFC9085] Previdi, S., Talaulikar, K., Ed., Filsfils, C., Gredler, H., and M. Chen, "Border Gateway Protocol - Link State (BGP-LS) Extensions for Segment Routing", RFC 9085, DOI 10.17487/RFC9085, August 2021, . [RFC9356] Talaulikar, K. and P. Psenak, "Advertising L2 Bundle Member Link Attributes in OSPF", RFC 9356, January 2023, . Glctgp, et al. Expires April 15, 2025 [Page 8] Internet-Draft L2 Bundle Member Remote ID October 2024 10.2. Informational References [802.1AB] "IEEE Standard for Local and metropolitan area networks- Station and Media Access Control Connectivity Discovery", IEEE Std 802.1AB-2016, 29 January 2016. [RFC9552] Talaulikar, K., Ed., "Distribution of Link-State and Traffic Engineering Information Using BGP", RFC 9552, DOI 10.17487/RFC9552, December 2023, . Authors' Addresses Liyan Gong China Mobile China Email: gongliyan@chinamobile.com Changwang Lin New H3C Technologies China Email: linchangwang.04414@h3c.com Mengxiao Chen New H3C Technologies China Email: chen.mengxiao@h3c.com Ketan Talaulikar Cisco Systems India Email: ketant.ietf@gmail.com Les Ginsberg Cisco Systems United States of America Email: ginsberg@cisco.com Glctgp, et al. Expires April 15, 2025 [Page 9] Internet-Draft L2 Bundle Member Remote ID October 2024 Peter Psenak Cisco Systems Apollo Business Center Mlynske nivy 43 Bratislava 821 09 Slovakia Email: ppsenak@cisco.com Glctgp, et al. Expires April 15, 2025 [Page 10]