Network Working Group J. Dong Internet-Draft S. Zhuang Intended status: Standards Track Huawei Technologies Expires: 6 May 2027 G. Van de Velde Nokia J. Tantsura Nvidia 2 November 2026 BGP Extended Community for Identifying the Target Nodes draft-ietf-idr-node-target-ext-comm-04 Abstract BGP has been used to distribute different types of routing and policy information. In some cases, the information distributed may be only intended for one or a particular group of BGP nodes in the network. Currently BGP does not have a generic mechanism to designate the target nodes of the routing information. This document defines a new type of BGP Extended Community called "Node Target" for this purpose. 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 May 2027. Copyright Notice Copyright (c) 2026 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 Dong, et al. Expires 6 May 2027 [Page 1] Internet-Draft BGP Node Target Extended Community November 2026 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. Node Target Extended Communities . . . . . . . . . . . . . . 3 3. Procedures . . . . . . . . . . . . . . . . . . . . . . . . . 4 4. Operational Considerations . . . . . . . . . . . . . . . . . 5 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5 6. Security Considerations . . . . . . . . . . . . . . . . . . . 6 7. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 6 8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 6 9. References . . . . . . . . . . . . . . . . . . . . . . . . . 6 9.1. Normative References . . . . . . . . . . . . . . . . . . 6 9.2. Informative References . . . . . . . . . . . . . . . . . 7 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 7 1. Introduction BGP [RFC4271] has been used to distribute different types of routing and policy information. In some cases, the information distributed may be only intended for one or a group of receiving BGP nodes in the network. One typical use case is the distribution of BGP Flow Spec [RFC8955] [RFC8956] rules only to a particular group of BGP nodes. Such a targeted distribution mechanism is considered useful as it can save resource on nodes which do not need that information. Currently BGP does not have a generic mechanism to designate the set of nodes to which the information is to be distributed. Route Target (RT) as defined in [RFC4364] was designed for the matching of VPN routes into the target VPN Routing and Forwarding tables (VRFs) on the PE nodes. [RFC9830] introduces the mechanism of steering the SR Policy information to the target head end node based on RT, it is only applicable to the SR Policy Address Family. Although it is possible to reuse RT to control the distribution of non-VPN information to one or a group of receiving nodes, such mechanism is not applicable when the information to be distributed is VPN-specific and is advertised with another set of RTs for the VRF matching, as the matching of any of the VPN RT in the BGP route would result in that route being imported to a local VRF, regardless of whether the receiving node is the target node or not. Thus a general mechanism which is independent from the control of importing VPN routes to VRFs is needed. Dong, et al. Expires 6 May 2027 [Page 2] Internet-Draft BGP Node Target Extended Community November 2026 Another possible approach is to configure, on each router, a community and the corresponding policies to match the community to determine whether to accept the received routes or not. Such mechanism relies on manual configuration thus is considered error- prone. It is preferable by some operators that an automatic approach can be provided, which would make the operation much easier. This document defines a new type of BGP Extended Community called "Node Target". It can be used by a receiving BGP node to determine whether it is the target of the BGP information. 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. Node Target Extended Communities This section defines a new BGP Extended Community [RFC4360] called "Node Target Extended Community". It can be a transitive extended community with the high-order octet of the type set to 0x01, or a non-transitive extended community with the high-order octet type set to 0x41. The sub-type of the Node Target Extended Community is 0x09. The format of Node Target Extended Community is shown in Figure 1. 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | 0x01 or 0x41 | 0x09 | Target BGP Identifier | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Target BGP Identifier (cont.) | Reserved | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 1. Node Target extended community Where: Target BGP Identifier (4 octets): The BGP Identifier of a target node. It is a 4-octet, unsigned, non-zero integer as defined in [RFC6286]. Reserved field (2 octets): Reserved for future use, MUST be set to zero on transmission and ignored on receipt. Dong, et al. Expires 6 May 2027 [Page 3] Internet-Draft BGP Node Target Extended Community November 2026 One or more Node Target extended communities MAY be carried in an Update message to designate a group of target BGP nodes. 3. Procedures In this section, the mechanism for intra-domain scenario is described, the mechanism for inter-domain scenario is for further study. The domain here refers to an administrative domain, which may consists of one or multiple ASes managed by a single operator. When a network controller or BGP speaker plans to advertise BGP routing or policy information only to one or a group of BGP nodes in the network, it MUST put the BGP Identifier of each target node into a list of Node Target extended communities, and attach the Node Target extended communities to the BGP Update to be advertised. Duplicated BGP identifiers MUST NOT be carried in the Node Target extended communities of a BGP Update. When a BGP speaker receives a BGP Update which contains one or more Node Target extended communities, it MUST check the BGP Identifiers carried in the Node Target extended communities of the Update. An invalid BGP Identifier (e.g. 0.0.0.0) received in Node Target Extended Communities MUST be ignored on receipt and SHOULD be logged. If multiple Node Target extended communities in an Update carry the same BGP Identifier, the receiver SHOULD treat them as a single occurrence of that target. Duplicate occurrences have no additional meaning and SHOULD be silently ignored. If any of the Target BGP Identifiers in the Node Target extended communities matches the local BGP Identifier, this node is one of the target nodes of the Update, information in the Update is eligible for installation on this node. If none of the Target BGP Identifiers in the Node Target extended communities matches with the local BGP Identifier, this node is not among the target nodes of the Update, information in the UPDATE MAY still be accepted by the BGP speaker (e.g. stored in Adj-RIB-In), but it MUST NOT be installed locally in the RIB/FIB/ACL etc. of this node, and MUST NOT be advertised further to other nodes. Routing information that is not targeted to this node SHOULD still be observable for diagnostic purposes, this can be done by an indication that the route does not pass the Node Target check , together with the Node Target extended communities received. A counter of routes not passing the node-target check SHOULD also be kept. The specific storage location is implementation-dependent. FlowSpec is a motivating use case for this mechanism. When a FlowSpec NLRI carries Node Target extended communities, the Node Target check SHOULD be applied before the validation procedure defined in [RFC8955]. Dong, et al. Expires 6 May 2027 [Page 4] Internet-Draft BGP Node Target Extended Community November 2026 The mechanism of using Node Target extended community to control the BGP route distribution only to particular BGP nodes is out of the scope and will be specified in a separate document. 4. Operational Considerations An operator who is responsible for the administration of one or multiple ASes need to ensure each BGP speaker in the network is assigned with a unique BGP Identifier. The Node Target extended communities may be originated by a network controller or a BGP speaker, In order to construct the list of node targets, an inventory of the BGP Identifiers of the target nodes in the domain MUST be maintained. The mechanism used to obtain and update such inventory is out of the scope of this document. Operators are expected to derive it from their existing inventory, orchestration, or configuration management systems.. Each node target consumes an 8-octet extended community, and targets are enumerated individually. A large group of node target extended communities therefore adds substantially to the size of the Update. Operators SHOULD keep the target groups to a practical size, and SHOULD consider whether a small set of target nodes can meet the deployment need. Implementations MAY impose a local limit on the number of Node Target extended communities per Update. The Node Target extended community can be deployed incrementally. BGP speakers that do not understand it ignore it and process the Update according to normal BGP procedures. This ensures target nodes obtain the information they need, but may also result in unnecessary state on legacy nodes. If the information is FlowSpec, legacy speakers may install unnecessary FlowSpec rules, potentially affecting traffic that matches those rules. This may be mitigated by setting appropriate routing policies on the legacy BGP nodes. Operators should be aware of this requirement during the migration. 5. IANA Considerations Per the early allocation process, IANA has assigned the sub-type value 0x09 for "Node Target Extended Community" from the "Transitive IPv4-Address-Specific Extended Community Sub-Types" registry of the "BGP Extended Communities" registry. Per the early allocation process, IANA has assigned the sub-type value 0x09 for "Node Target Extended Community" from the "Non- Transitive IPv4-Address-Specific Extended Community Sub-Types" registry of the "BGP Extended Communities" registry. Dong, et al. Expires 6 May 2027 [Page 5] Internet-Draft BGP Node Target Extended Community November 2026 6. Security Considerations The mechanism defined in this document can limit the scope of the receiving nodes of BGP Updates, which make it possible for an attacker to do fine-grained targeting of malicious BGP Updates only to a restricted set of routers. This may make it more difficult for a network administrator to discover an attack. This may be mitigated by filtering the Node Target extended communities at the administrative network boundaries. A misconfigured or injected Node Target extended community could suppress route installation across an entire administrative domain without generating any protocol error. Operators should treat target lists as security-sensitive configuration. 7. Contributors Haibo Wang Email: rainsword.wang@huawei.com 8. Acknowledgements The authors would like to thank Zhenbin Li, Ercin Torun, Jeff Haas, Robert Raszuk and John Scudder for the review and discussion of this document. 9. References 9.1. Normative References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997, . [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, . [RFC4360] Sangli, S., Tappan, D., and Y. Rekhter, "BGP Extended Communities Attribute", RFC 4360, DOI 10.17487/RFC4360, February 2006, . [RFC6286] Chen, E. and J. Yuan, "Autonomous-System-Wide Unique BGP Identifier for BGP-4", RFC 6286, DOI 10.17487/RFC6286, June 2011, . Dong, et al. Expires 6 May 2027 [Page 6] Internet-Draft BGP Node Target Extended Community November 2026 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, May 2017, . 9.2. Informative References [RFC4364] Rosen, E. and Y. Rekhter, "BGP/MPLS IP Virtual Private Networks (VPNs)", RFC 4364, DOI 10.17487/RFC4364, February 2006, . [RFC8955] Loibl, C., Hares, S., Raszuk, R., McPherson, D., and M. Bacher, "Dissemination of Flow Specification Rules", RFC 8955, DOI 10.17487/RFC8955, December 2020, . [RFC8956] Loibl, C., Ed., Raszuk, R., Ed., and S. Hares, Ed., "Dissemination of Flow Specification Rules for IPv6", RFC 8956, DOI 10.17487/RFC8956, December 2020, . [RFC9830] Previdi, S., Filsfils, C., Talaulikar, K., Ed., Mattes, P., and D. Jain, "Advertising Segment Routing Policies in BGP", RFC 9830, DOI 10.17487/RFC9830, September 2025, . Authors' Addresses Jie Dong Huawei Technologies Huawei Campus, No. 156 Beiqing Rd. Beijing 100095 China Email: jie.dong@huawei.com Shunwan Zhuang Huawei Technologies Huawei Campus, No. 156 Beiqing Rd. Beijing 100095 China Email: zhuangshunwan@huawei.com Dong, et al. Expires 6 May 2027 [Page 7] Internet-Draft BGP Node Target Extended Community November 2026 Gunter Van de Velde Nokia Antwerp Belgium Email: gunter.van_de_velde@nokia.com Jeff Tantsura Nvidia Email: jefftant.ietf@gmail.com Dong, et al. Expires 6 May 2027 [Page 8]