Network Working Group L. Gong Internet Draft China Mobile Intended status: Standards Track C. Lin Expires: August 24, 2024 M. Chen New H3C Technologies February 26, 2024 IGP Logical Link Discovery Protocol (LLDP) Interface Identifier Discovery draft-gong-lsr-lldp-interface-id-00 Abstract This document describes how OSPF and IS-IS would use LLDP to discover the identifier of remote interface. The typical applications are the topology discovery of Layer 2 bundle members and unnumbered interfaces. 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), its areas, and its working groups. Note that other groups may also distribute working documents as Internet- Drafts. 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." The list of current Internet-Drafts can be accessed at http://www.ietf.org/ietf/1id-abstracts.txt The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html This Internet-Draft will expire on August 24, 2024. Copyright Notice Copyright (c) 2024 IETF Trust and the persons identified as the document authors. All rights reserved. Gong, et al. Expire August 24, 2024 [Page 1] Internet-Draft LLDP Interface ID Discovery February 2024 This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (http://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 1.1. Requirements Language.....................................2 2. Use Cases......................................................3 2.1. Topology Discovery of Layer 2 Bundle Members..............3 2.1.1. Existing Solution....................................3 2.1.2. Proposed Solution....................................4 2.2. Topology Discovery of Unnumbered Interfaces...............5 3. LLDP Extension.................................................5 4. BGP-LS Extension...............................................6 5. Security Considerations........................................6 6. IANA Considerations............................................6 7. References.....................................................6 7.1. Normative References......................................6 7.2. Informational References..................................7 Authors' Addresses................................................7 1. Introduction The Link Layer Discovery Protocol (LLDP) [802.1AB] is a standard link layer protocol that allows network devices to discover neighbors and exchange information. Using the LLDP, a device can get its neighbor's MAC address or interface name through the Port ID TLV. However, in some scenarios, there are requirements to get the interface identifier of the neighbor. The typical applications are the topology discovery of Layer 2 bundle members and unnumbered interfaces. This document specifies the LLDP IETF Organizationally Specific TLV that carries the interface identifier for OSPF and IS-IS protocols. 1.1. Requirements Language The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and Gong, et al. Expires August 24, 2024 [Page 2] Internet-Draft LLDP Interface ID Discovery February 2024 "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 Cases 2.1. Topology Discovery of Layer 2 Bundle Members BGP-LS [RFC7752] is widely used for collection of topology information from IGP. In networks where L2 bundle is deployed, the connectivity relationships between bundle members are required to be collected by the controller, for traffic engineering purposes. When advertising the L2 bundles in OSPF [RFC9356] and IS-IS [RFC8668], each L2 bundle member can carry an OSPF Local/Remote Interface ID TLV or an IS-IS Link Local/Remote Identifiers TLV, which contains both the IDs of local interface and remote interface. However, IGP has no means of automatically obtaining the remote interface ID. An existing solution is described in Section 2.1.1. The LLDP is used to exchange interface names between L2 bundle members. In addition to BGP-LS, the controller collects interface and LLDP information through NETCONF. Section 2.1.2 proposes a new solution. The LLDP is extended to exchange interface IDs between L2 bundle members and advertises the pairs into IGP and BGP-LS. 2.1.1. Existing Solution The local interface IDs of L2 bundle members are advertised in IGP, and collected by the controller using BGP-LS. The L2 bundle members run LLDP to exchange the interface name with neighbors. The controller uses NETCONF to collect the pairing relationships between the interface names of member links, along with the correspondence between interface names and interface IDs, from both ends of the L2 bundle. Combining the information collected from BGP-LS and NETCONF, the controller can figure out the topology of L2 bundle members. Gong, et al. Expires August 24, 2024 [Page 3] Internet-Draft LLDP Interface ID Discovery February 2024 +----------+ BGP-LS |Controller|<--------------+ +----------+ + ^ ^ | NETCONF | | NETCONF | +----------+ +----------+ | | | | | | | +----+ L2-Bundle +----+ +----+ | | /---member 1---\ | | | | | R1 +-----member 2-----+ R2 +---+ R3 + | | \---member 3---/ | | | | +----+ +----+ +----+ ^ ^ | | +-------- LLDP --------+ interface name of member links Figure 1 Information collected through BGP-LS: o R3: Local Interface ID of L2-bundle Members (originally advertised by R1 and R2) Information collected through NETCONF: o R1: Local Interface ID & Name of L2-bundle Members o R2: Local Interface ID & Name of L2-bundle Members o LLDP (from R1/R2): Pairs 2.1.2. Proposed Solution The L2 bundle members run LLDP to exchange the interface ID with neighbors using the new-defined TLV in Section 3. The pairing relationships between the interface IDs of member links are advertised in IGP. In OSPF, each L2 bundle member carries an OSPF Local/Remote Interface ID TLV. In IS-IS, each L2 bundle member carries an IS-IS Link Local/Remote Identifiers TLV. The controller only needs to collect the topology information using BGP-LS from one node in the IGP area. Gong, et al. Expires August 24, 2024 [Page 4] Internet-Draft LLDP Interface ID Discovery February 2024 +----------+ BGP-LS |Controller|<--------------+ +----------+ + | | | | | +----+ L2-Bundle +----+ +----+ | | /---member 1---\ | | | | | R1 +-----member 2-----+ R2 +---+ R3 + | | \---member 3---/ | | | | +----+ +----+ +----+ ^ ^ | | +-------- LLDP --------+ interface ID of member links Figure 1 Information collected through BGP-LS: o R3: Pairs of L2-bundle Members (originally advertised by R1 and R2) 2.2. Topology Discovery of Unnumbered Interfaces An unnumbered interface borrows the IP address from other interfaces. When unnumbered interfaces are deployed, multiple interfaces of a router can share the same IP addresses. Based on the information collected by BGP-LS, the controller cannot figure out the connectivity relationships between unnumbered interfaces only according to the IP addresses. Similar with the solution in Section 2.1.2, unnumbered interfaces can run LLDP to exchange the interface ID and then advertise the pairs in IGP. 3. LLDP Extension LLDP TLVs that belong to an organization are identified by the inclusion of the organization's OUI (Organizationally Unique Identifier) and an organizationally defined subtype in the initial octets of the information field. This document defines a new IETF specific subtype, interface ID, under the IANA OUI. The LLDP IETF Organizationally Specific TLV of Gong, et al. Expires August 24, 2024 [Page 5] Internet-Draft LLDP Interface ID Discovery February 2024 the new-defined subtype carries the local identifier of interface, which 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 (127) | Length (8) | OUI (3 Octets) 00-00-5E | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | OUI Continued | Subtype (TBD) | Interface ID (4 Octets) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Interface ID Continued | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ o Type: IETF Organizationally Specific TLV type value, 127. o Length: Length of the remainder of the TLV, 8. o OUI: Organizationally Unique Identifier. For IETF use, this field is the IANA OUI (00-00-5E) as specified in RFC 7042. o Subtype: Subtype for interface ID, TBD. o Interface ID: Local identifier of interface, 4 octets. 4. BGP-LS Extension This document extends BGP-LS to allow L2 Bundle Member Attributes TLV [RFC9085] to carry Link Local/Remote Identifiers TLV [RFC9552] as its sub-TLV. 5. Security Considerations TBD. 6. IANA Considerations TBD. 7. References 7.1. Normative 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. [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. Gong, et al. Expires August 24, 2024 [Page 6] Internet-Draft LLDP Interface ID Discovery February 2024 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, May 2017 [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, . [RFC9552] Talaulikar, K., Ed., "Distribution of Link-State and Traffic Engineering Information Using BGP", RFC 9552, DOI 10.17487/RFC9552, December 2023, . 7.2. Informational References [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, . [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, . [RFC9356] Talaulikar, K. and P. Psenak, "Advertising L2 Bundle Member Link Attributes in OSPF", RFC 9356, January 2023, . Authors' Addresses Liyan Gong China Mobile China Email: gongliyan@chinamobile.com Changwang Lin New H3C Technologies China Email: linchangwang.04414@h3c.com Gong, et al. Expires August 24, 2024 [Page 7] Internet-Draft LLDP Interface ID Discovery February 2024 Mengxiao Chen New H3C Technologies China Email: chen.mengxiao@h3c.com Gong, et al. Expires August 24, 2024 [Page 8]