Link State Routing (LSR) Working Group A. Lindem, Ed. Internet-Draft LabN Consulting, L.L.C. Intended status: Standards Track P. Psenak Expires: 20 June 2025 Cisco Systems Y. Qu Futurewei Technologies 17 December 2024 Extensions to OSPF for Advertising Prefix Administrative Tags draft-ietf-lsr-ospf-admin-tags-23 Abstract It is useful for routers in OSPFv2 and OSPFv3 routing domains to be able to associate tags with prefixes. Previously, OSPFv2 and OSPFv3 were relegated to a single tag and only for AS External and Not-So- Stubby-Area (NSSA) prefixes. With the flexible encodings provided by OSPFv2 Prefix/Link Attribute Advertisement and OSPFv3 Extended LSAs, multiple administrative tags may be advertised for all types of prefixes. These administrative tags can be used for many applications including route redistribution policy, selective prefix prioritization, selective IP Fast-ReRoute (IPFRR) prefix protection, and many others. 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 20 June 2025. Copyright Notice Copyright (c) 2024 IETF Trust and the persons identified as the document authors. All rights reserved. Lindem, et al. Expires 20 June 2025 [Page 1] Internet-Draft OSPF Administrative Tags December 2024 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. Administrative Tag Sub-TLV . . . . . . . . . . . . . . . . . 3 3. Administrative Tag Applicability . . . . . . . . . . . . . . 4 4. Protocol Operation . . . . . . . . . . . . . . . . . . . . . 5 4.1. Equal-Cost Multipath Applicability . . . . . . . . . . . 6 5. BGP-LS Advertisement . . . . . . . . . . . . . . . . . . . . 6 6. Management Considerations . . . . . . . . . . . . . . . . . . 6 7. YANG Data Model . . . . . . . . . . . . . . . . . . . . . . . 6 7.1. Tree for the YANG Data Model . . . . . . . . . . . . . . 7 7.2. YANG Data Model for OSPF Prefix Administrative Tags . . . 9 8. Security Considerations . . . . . . . . . . . . . . . . . . . 16 9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 17 10. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 17 11. Normative References . . . . . . . . . . . . . . . . . . . . 18 12. Informative References . . . . . . . . . . . . . . . . . . . 19 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 20 1. Introduction It is useful for routers in OSPFv2 [RFC2328] and OSPFv3 [RFC5340] routing domains to be able to associate tags with prefixes. Previously, OSPFv2 and OSPFv3 were relegated to a single tag and only for AS External and Not-So-Stubby-Area (NSSA) prefixes. With the flexible encodings provided by OSPFv2 Prefix/Link Attribute Advertisement ([RFC7684]) and OSPFv3 Extended LSA ([RFC8362]), multiple administrative tags may be advertised for all types of prefixes. These administrative tags can be used in many applications including (but not limited to): 1. Controlling which routes are redistributed into other protocols for re-advertisement. 2. Prioritizing selected prefixes for faster convergence and installation in the forwarding plane. Lindem, et al. Expires 20 June 2025 [Page 2] Internet-Draft OSPF Administrative Tags December 2024 3. Identifying selected prefixes for Loop-Free Alternative (LFA) protection. Throughout this document, OSPF is used when the text applies to both OSPFv2 and OSPFv3. OSPFv2 or OSPFv3 is used when the text is specific to one version of the OSPF protocol. The definition of the 64-bit tag was considered but discard given that there is no strong requirement or use case. The IS-IS protocol supports a similar mechanism that is described in RFC 5130 [RFC5130]. 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. Administrative Tag Sub-TLV This document creates a new Administrative Tag Sub-TLV for OSPFv2 and OSPFv3. This Sub-TLV specifies one or more 32-bit unsigned integers that may be associated with an OSPF advertised prefix. The precise usage of these tags is beyond the scope of this document. The format of the Administrative Tag TLV is as follows: Lindem, et al. Expires 20 June 2025 [Page 3] Internet-Draft OSPF Administrative Tags December 2024 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 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | First Administrative Tag | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | o | o | o | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Last Administrative Tag | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Type A 16-bit field set to: TBD1: "OSPF Extended Prefix TLV Sub-TLV" Registry TBD2: "OSPFv3 Extended-LSA Sub-TLV" Registry TBD3: "OSPFv3 SRv6 Locator LSA Sub-TLVs" Registry Length A 16-bit field that indicates the length of the value portion in octets and MUST be a multiple of 4 octets dependent on the number of administrative tags advertised. At least one administrative tag MUST be advertised. Value A variable length list of one or more administrative tags. Figure 1: Administrative Tag Sub-TLV This sub-TLV will carry one or more 32-bit unsigned integer values that will be used as administrative tags. If the length is 0 or not a multiple of 4 octets, the sub-TLV MUST be ignored and the reception SHOULD be logged for further analysis (subject to rate-limiting). 3. Administrative Tag Applicability The administrative tag TLV specified herein will be valid as a sub- TLV of the following TLVs specified in [RFC7684]: 1. Extended Prefix TLV advertised in the OSPFv2 Extended Prefix LSA The administrative tag TLV specified herein will be valid as a sub- TLV of the following TLVs specified in [RFC8362]: 1. Inter-Area-Prefix TLV advertised in the E-Inter-Area-Prefix-LSA Lindem, et al. Expires 20 June 2025 [Page 4] Internet-Draft OSPF Administrative Tags December 2024 2. Intra-Area-Prefix TLV advertised in the E-Intra-Area-Prefix-LSA. 3. External-Prefix TLV advertised in the E-AS-External-LSA and the E-NSSA-LSA The administrative tag TLV specified herein will be valid as a sub- TLV of the following TLVs specified in [RFC9513]: 1. SRv6 Locator TLV advertised in the SRv6 Locator LSA 4. Protocol Operation An OSPF router supporting this specification MUST be able to advertise and interpret at least one tag for all type of prefixes. An OSPF router supporting this specification MAY be able to advertise and propagate multiple tags. The maximum tags that an implementation supports is a local matter depending upon supported applications using prefix tags. Depending on the application, the number of tags supported by the OSPF routers in the OSPF routing domain MAY limit deployment of that application. When tags are advertised for AS External or NSSA LSA prefixes, the existing tag in the OSPFv2 and OSPFv3 AS-External-LSA and NSSA-LSA encodings MUST be utilized for the first tag. Additional tags MAY be advertised using the Administrative Tag Sub-TLV speficified in this document. This will facilitate backward compatibility with implementations that do not support this specification. An OSPF router supporting this specification SHOULD propagate administrative tags when acting as an Area Border Router and originating summary advertisements into other areas (unless inhibited by local policy Section 6). Similarly, an OSPF router supporting this specification and acting as an ABR for a Not-So-Stubby Area (NSSA) SHOULD propagate tags when translating NSSA routes to AS External advertisements [RFC3101] (also subject to local policy Section 6). There is no implied meaning to the ordering of the tags that indicates a certain operation or set of operations need be performed based on the order of the tags. Each tag SHOULD be treated as an autonomous identifier that MAY be used in policy to perform a policy action. Whether or not tag A precedes or succeeds tag B SHOULD NOT change the meaning of the tags The number of tags supported by an Area Border Router (ABR) MAY limit the number of tags that are propagated. When propagating multiple tags between areas as previously described, the order of the tags MUST be preserved so that implementations supporting fewer tags will have a consistent view across areas. Lindem, et al. Expires 20 June 2025 [Page 5] Internet-Draft OSPF Administrative Tags December 2024 For configured area ranges, NSSA ranges, and configured aggregation of redistributed routes, tags from component routes SHOULD NOT be propagated to the summary. Implementations SHOULD provide a mechanism to configure multiple tags for area ranges, NSSA ranges, and redistributed route summaries. 4.1. Equal-Cost Multipath Applicability When multiple LSAs contribute to an OSPF route, it is possible that these LSAs will all have different tags. In this situation, the OSPF ABR propating the route to other areas with inter-area LSAs MUST associate the tags from one of the LSAs contributing a path and, if the implementation supports multiple tags, MAY associate tags from multiple contributing LSAs up to the maximum number of tags supported. It is RECOMMENDED that tags from LSAs are added to the path in ascending order of LSA originator Router-ID. 5. BGP-LS Advertisement BGP-LS [RFC9552] introduced the support for advertising administrative tags associated with prefixes using the BGP-LS IGP Route Tag TLV (TLV 1153). This BGP-LS TLV is used to advertise the OSPF Administrative Tags specified in this document. 6. Management Considerations Implementations MAY include configuration of policies to modify the advertisement of tags for redistributed prefixes. Implementations MAY also include configuration of policies to modify the propagation of admin-tags between areas (OSPFv2 Extended Prefix LSAs, OSPFv3 E- Inter-Area-Prefix-LSAs, and translated OSPFv3 E-AS-External-LSAs). However, the default behavior SHOULD be to advertise or propagate the lesser number of all the tags associated with the prefix or the maximum number of tags supported by the implementation. Both the support of this specification and the number of tags supported by OSPF routers within an OSPF routing domain will limit the usefulness and deployment of applications utilizing tags. 7. YANG Data Model YANG [RFC7950] is a data definition language used to define the contents of a conceptual data store that allows networked devices to be managed using NETCONF [RFC6241] or RESTCONF [RFC8040]. Lindem, et al. Expires 20 June 2025 [Page 6] Internet-Draft OSPF Administrative Tags December 2024 This section defines a YANG data model that can be used to configure and manage the prefix administrative tags defined in this document, which augments the OSPF YANG data model [RFC9129] and the OSPFv3 Extended LSA YANG data model [RFC9587]. 7.1. Tree for the YANG Data Model This document uses the graphical representation of data models per [RFC8340]. The following show the tree diagram of the module: module: ietf-ospf-admin-tags augment /rt:routing/rt:control-plane-protocols /rt:control-plane-protocol/ospf:ospf/ospf:areas/ospf:area /ospf:ranges/ospf:range: +--rw admin-tags +--rw admin-tag* uint32 augment /rt:routing/rt:control-plane-protocols /rt:control-plane-protocol/ospf:ospf/ospf:areas/ospf:area /ospf:ranges/ospf:range: +--rw admin-tag* uint32 augment /rt:routing/rt:control-plane-protocols /rt:control-plane-protocol/ospf:ospf/ospf:areas/ospf:area /ospf:interfaces/ospf:interface: +--rw local-prefix-admin-tags +--rw default-admin-tag* uint32 +--rw specific-prefix-admin-tag* [prefix] +--rw prefix inet:ip-prefix +--rw admin-tag* uint32 augment /rt:routing/rt:control-plane-protocols /rt:control-plane-protocol/ospf:ospf/ospf:local-rib /ospf:route/ospf:next-hops/ospf:next-hop: +--ro admin-tag* uint32 augment /rt:routing/rt:control-plane-protocols /rt:control-plane-protocol/ospf:ospf/ospf:areas/ospf:area /ospf:interfaces/ospf:interface/ospf:database /ospf:link-scope-lsa-type/ospf:link-scope-lsas /ospf:link-scope-lsa/ospf:version/ospf:ospfv2/ospf:ospfv2 /ospf:body/ospf:opaque/ospf:extended-prefix-opaque /ospf:extended-prefix-tlv: +--ro prefix-admin-tag-sub-tlv +--ro admin-tag* uint32 augment /rt:routing/rt:control-plane-protocols /rt:control-plane-protocol/ospf:ospf/ospf:areas/ospf:area /ospf:database/ospf:area-scope-lsa-type/ospf:area-scope-lsas /ospf:area-scope-lsa/ospf:version/ospf:ospfv2/ospf:ospfv2 Lindem, et al. Expires 20 June 2025 [Page 7] Internet-Draft OSPF Administrative Tags December 2024 /ospf:body/ospf:opaque/ospf:extended-prefix-opaque /ospf:extended-prefix-tlv: +--ro prefix-admin-tag-sub-tlv +--ro admin-tag* uint32 augment /rt:routing/rt:control-plane-protocols /rt:control-plane-protocol/ospf:ospf/ospf:database /ospf:as-scope-lsa-type/ospf:as-scope-lsas/ospf:as-scope-lsa /ospf:version/ospf:ospfv2/ospf:ospfv2/ospf:body/ospf:opaque /ospf:extended-prefix-opaque/ospf:extended-prefix-tlv: +--ro prefix-admin-tag-sub-tlv +--ro admin-tag* uint32 augment /rt:routing/rt:control-plane-protocols /rt:control-plane-protocol/ospf:ospf/ospf:areas/ospf:area /ospf:database/ospf:area-scope-lsa-type/ospf:area-scope-lsas /ospf:area-scope-lsa/ospf:version/ospf:ospfv3/ospf:ospfv3 /ospf:body/ospfv3-e-lsa:e-inter-area-prefix /ospfv3-e-lsa:e-inter-prefix-tlvs /ospfv3-e-lsa:inter-prefix-tlv: +--ro prefix-admin-tag-sub-tlv +--ro admin-tag* uint32 augment /rt:routing/rt:control-plane-protocols /rt:control-plane-protocol/ospf:ospf/ospf:areas/ospf:area /ospf:database/ospf:area-scope-lsa-type/ospf:area-scope-lsas /ospf:area-scope-lsa/ospf:version/ospf:ospfv3/ospf:ospfv3 /ospf:body/ospfv3-e-lsa:e-intra-area-prefix /ospfv3-e-lsa:e-intra-prefix-tlvs /ospfv3-e-lsa:intra-prefix-tlv: +--ro prefix-admin-tag-sub-tlv +--ro admin-tag* uint32 augment /rt:routing/rt:control-plane-protocols /rt:control-plane-protocol/ospf:ospf/ospf:database /ospf:as-scope-lsa-type/ospf:as-scope-lsas/ospf:as-scope-lsa /ospf:version/ospf:ospfv3/ospf:ospfv3/ospf:body /ospfv3-e-lsa:e-as-external/ospfv3-e-lsa:e-external-tlvs /ospfv3-e-lsa:external-prefix-tlv: +--ro prefix-admin-tag-sub-tlv +--ro admin-tag* uint32 augment /rt:routing/rt:control-plane-protocols /rt:control-plane-protocol/ospf:ospf/ospf:areas/ospf:area /ospf:database/ospf:area-scope-lsa-type/ospf:area-scope-lsas /ospf:area-scope-lsa/ospf:version/ospf:ospfv3/ospf:ospfv3 /ospf:body/ospfv3-e-lsa:e-nssa/ospfv3-e-lsa:e-external-tlvs /ospfv3-e-lsa:external-prefix-tlv: +--ro prefix-admin-tag-sub-tlv +--ro admin-tag* uint32 Lindem, et al. Expires 20 June 2025 [Page 8] Internet-Draft OSPF Administrative Tags December 2024 7.2. YANG Data Model for OSPF Prefix Administrative Tags The following is the YANG module: file "ietf-ospf-admin-tags@2024-07-22.yang" module ietf-ospf-admin-tags { yang-version 1.1; namespace "urn:ietf:params:xml:ns:yang:ietf-ospf-admin-tags"; prefix ospf-admin-tags; import ietf-routing { prefix rt; reference "RFC 8349: A YANG Data Model for Routing Management (NMDA Version)"; } import ietf-ospf { prefix ospf; reference "RFC 9129: YANG Data Model for the OSPF Protocol"; } import ietf-inet-types { prefix inet; reference "RFC 6991: Common YANG Data Types"; } import ietf-ospfv3-extended-lsa { prefix ospfv3-e-lsa; reference "RFC 9587: YANG Data Model for OSPFv3 Extended Link State Advertisements (LSAs)"; } organization "IETF LSR - Link State Routing Working Group"; contact "WG Web: WG List: Author: Yingzhen Qu Author: Acee Lindem Author: Peter Psenak "; description "This YANG module defines the configuration and operational state for OSPF administrative tags. Lindem, et al. Expires 20 June 2025 [Page 9] Internet-Draft OSPF Administrative Tags December 2024 This YANG model conforms to the Network Management Datastore Architecture (NMDA) as described in RFC 8342. Copyright (c) 2024 IETF Trust and the persons identified as authors of the code. All rights reserved. Redistribution and use in source and binary forms, with or without modification, is permitted pursuant to, and subject to the license terms contained in, the Revised BSD License set forth in Section 4.c of the IETF Trust's Legal Provisions Relating to IETF Documents (https://trustee.ietf.org/license-info). This version of this YANG module is part of RFC XXXX; see the RFC itself for full legal notices. 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 (RFC 2119) (RFC 8174) when, and only when, they appear in all capitals, as shown here."; reference "RFC XXXX"; revision 2024-07-22 { description "Initial revision."; reference "RFC XXXX: Extensions to OSPF for Advertising Prefix Administrative Tags."; } grouping prefix-admin-tag-sub-tlv { description "Prefix Administrative Tag sub-TLVs."; container prefix-admin-tag-sub-tlv { config false; description "Prefix admin tag sub-TLV."; leaf-list admin-tag { type uint32; description "Administrative tags."; } } } /* Configuration */ Lindem, et al. Expires 20 June 2025 [Page 10] Internet-Draft OSPF Administrative Tags December 2024 augment "/rt:routing/rt:control-plane-protocols/" + "rt:control-plane-protocol/ospf:ospf/" + "ospf:areas/ospf:area/ospf:ranges/ospf:range" { when "derived-from-or-self(../../../../../" + "rt:type, 'ospf:ospf')" { description "This augments the OSPF routing protocol area range configuration."; } description "This augments the OSPF protocol area range configuration with administrative tags. The configured tags will be advertised with summary prefix when it is active."; container admin-tags { when "../ospf:advertise = 'true'"; leaf-list admin-tag { type uint32; description "Administrative tags."; } description "OSPF prefix administrative tags."; } } augment "/rt:routing/rt:control-plane-protocols/" + "rt:control-plane-protocol/ospf:ospf/" + "ospf:areas/ospf:area/ospf:ranges/ospf:range" { when "derived-from-or-self(../../../../../" + "rt:type, 'ospf:ospf')" { description "This augments the OSPF routing protocol area range configuration."; } description "This augments summary route configuration with administrative tags."; leaf-list admin-tag { type uint32; description "Administrative tags."; } } augment "/rt:routing/rt:control-plane-protocols/" + "rt:control-plane-protocol/ospf:ospf/" + "ospf:areas/ospf:area/ospf:interfaces/ospf:interface" { when "derived-from-or-self(../../../../../" Lindem, et al. Expires 20 June 2025 [Page 11] Internet-Draft OSPF Administrative Tags December 2024 + "rt:type, 'ospf:ospf')" { description "This augments the OSPF routing protocol interface configuration."; } description "This augments the OSPF protocol interface configuration with Administrative Tags. The configured tags will be advertised with local prefixes configured for the interface."; container local-prefix-admin-tags { leaf-list default-admin-tag { type uint32; description "Administrative tags that will be associated with local prefixes if the prefix is not specified explicitly. If omitted, no admin tags are associated with local prefixes by default."; } list specific-prefix-admin-tag { key "prefix"; leaf prefix { type inet:ip-prefix; description "IPv4 or IPv6 prefix"; } leaf-list admin-tag { type uint32; description "Administrative tags that will be associated with the specified local prefix. If omitted, no admin tags are associated with the specified local prefix."; } description "Admin tags that are explicitly associated with the specified prefix."; } description "List of administrative tags that are to be advertised with interface local prefixes."; } } /* Local-RIB */ augment "/rt:routing/" + "rt:control-plane-protocols/rt:control-plane-protocol/" + "ospf:ospf/ospf:local-rib/ospf:route/ospf:next-hops/" + "ospf:next-hop" { description Lindem, et al. Expires 20 June 2025 [Page 12] Internet-Draft OSPF Administrative Tags December 2024 "This augments local-rib next-hop with administrative tags."; leaf-list admin-tag { type uint32; description "Administrative tags."; } } /* Database */ augment "/rt:routing/" + "rt:control-plane-protocols/rt:control-plane-protocol/" + "ospf:ospf/ospf:areas/ospf:area/" + "ospf:interfaces/ospf:interface/ospf:database/" + "ospf:link-scope-lsa-type/ospf:link-scope-lsas/" + "ospf:link-scope-lsa/ospf:version/ospf:ospfv2/" + "ospf:ospfv2/ospf:body/ospf:opaque/" + "ospf:extended-prefix-opaque/ospf:extended-prefix-tlv" { when "derived-from-or-self(../../../../../../../../../../" + "../../../../rt:type, 'ospf:ospfv2')" { description "This augmentation is only valid for OSPFv2."; } description "Prefix Administrative Tag Sub-TLVs for OSPFv2 extended prefix TLV in type 9 opaque LSA."; uses prefix-admin-tag-sub-tlv; } augment "/rt:routing/" + "rt:control-plane-protocols/rt:control-plane-protocol/" + "ospf:ospf/ospf:areas/" + "ospf:area/ospf:database/" + "ospf:area-scope-lsa-type/ospf:area-scope-lsas/" + "ospf:area-scope-lsa/ospf:version/ospf:ospfv2/" + "ospf:ospfv2/ospf:body/ospf:opaque/" + "ospf:extended-prefix-opaque/ospf:extended-prefix-tlv" { when "derived-from-or-self(../../../../../../../../../../" + "../../rt:type, 'ospf:ospfv2')" { description "This augmentation is only valid for OSPFv2."; } description "Prefix Administrative Tag Sub-TLVs for OSPFv2 extended prefix TLV in type 10 opaque LSA."; uses prefix-admin-tag-sub-tlv; } Lindem, et al. Expires 20 June 2025 [Page 13] Internet-Draft OSPF Administrative Tags December 2024 augment "/rt:routing/" + "rt:control-plane-protocols/rt:control-plane-protocol/" + "ospf:ospf/ospf:database/" + "ospf:as-scope-lsa-type/ospf:as-scope-lsas/" + "ospf:as-scope-lsa/ospf:version/ospf:ospfv2/" + "ospf:ospfv2/ospf:body/ospf:opaque/" + "ospf:extended-prefix-opaque/ospf:extended-prefix-tlv" { when "derived-from-or-self(../../../../../../../../" + "../../rt:type, 'ospf:ospfv2')" { description "This augmentation is only valid for OSPFv2."; } description "Prefix Administrative Tag Sub-TLVs for OSPFv2 extended prefix TLV in type 11 opaque LSA."; uses prefix-admin-tag-sub-tlv; } augment "/rt:routing/" + "rt:control-plane-protocols/rt:control-plane-protocol/" + "ospf:ospf/ospf:areas/ospf:area/ospf:database/" + "ospf:area-scope-lsa-type/ospf:area-scope-lsas/" + "ospf:area-scope-lsa/ospf:version/ospf:ospfv3/" + "ospf:ospfv3/ospf:body/ospfv3-e-lsa:e-inter-area-prefix/" + "ospfv3-e-lsa:e-inter-prefix-tlvs/" + "ospfv3-e-lsa:inter-prefix-tlv" { when "derived-from-or-self(../../../../../../../../../../" + "../../rt:type, 'ospf:ospfv3')" { description "This augmentation is only valid for OSPFv3."; } description "Augment OSPFv3 Inter-Area-Prefix TLV in the E-Inter-Area-Prefix LSA."; uses prefix-admin-tag-sub-tlv; } augment "/rt:routing/" + "rt:control-plane-protocols/rt:control-plane-protocol/" + "ospf:ospf/ospf:areas/ospf:area/ospf:database/" + "ospf:area-scope-lsa-type/ospf:area-scope-lsas/" + "ospf:area-scope-lsa/ospf:version/ospf:ospfv3/" + "ospf:ospfv3/ospf:body/ospfv3-e-lsa:e-intra-area-prefix/" + "ospfv3-e-lsa:e-intra-prefix-tlvs/" + "ospfv3-e-lsa:intra-prefix-tlv" { when "/rt:routing/rt:control-plane-protocols" + "/rt:control-plane-protocol/rt:type = 'ospf:ospfv3'" { description Lindem, et al. Expires 20 June 2025 [Page 14] Internet-Draft OSPF Administrative Tags December 2024 "This augmentation is only valid for OSPFv3."; } description "Augment OSPFv3 Intra-Area-Prefix TLV in the E-Intra-Area-Prefix LSA."; uses prefix-admin-tag-sub-tlv; } augment "/rt:routing/" + "rt:control-plane-protocols/rt:control-plane-protocol/" + "ospf:ospf/ospf:database/" + "ospf:as-scope-lsa-type/ospf:as-scope-lsas/" + "ospf:as-scope-lsa/ospf:version/ospf:ospfv3/" + "ospf:ospfv3/ospf:body/ospfv3-e-lsa:e-as-external/" + "ospfv3-e-lsa:e-external-tlvs/" + "ospfv3-e-lsa:external-prefix-tlv" { when "derived-from-or-self(../../../../../../../../" + "../../rt:type, 'ospf:ospfv3')" { description "This augmentation is only valid for OSPFv3."; } description "Augment OSPFv3 External-Prefix TLV in the E-AS-External-LSA."; uses prefix-admin-tag-sub-tlv; } augment "/rt:routing/" + "rt:control-plane-protocols/rt:control-plane-protocol/" + "ospf:ospf/ospf:areas/ospf:area/ospf:database/" + "ospf:area-scope-lsa-type/ospf:area-scope-lsas/" + "ospf:area-scope-lsa/ospf:version/ospf:ospfv3/" + "ospf:ospfv3/ospf:body/ospfv3-e-lsa:e-nssa/" + "ospfv3-e-lsa:e-external-tlvs/" + "ospfv3-e-lsa:external-prefix-tlv" { when "/rt:routing/rt:control-plane-protocols" + "/rt:control-plane-protocol/rt:type = 'ospf:ospfv3'" { description "This augmentation is only valid for OSPFv3."; } description "Augment OSPFv3 External-Prefix TLV in the E-NSSA-LSA."; uses prefix-admin-tag-sub-tlv; } } Lindem, et al. Expires 20 June 2025 [Page 15] Internet-Draft OSPF Administrative Tags December 2024 8. Security Considerations This document describes a generic mechanism for advertising administrative tags for OSPF prefixes. The administrative tags are generally less critical than the topology information currently advertised by the base OSPF protocol. The security considerations for the generic mechanism are dependent on their application. One such application is to control leaking of OSPF routes to other protocols (e.g., BGP [RFC4271]). If an attacker were able to modify the admin tags associated with OSPF routes and they were being used for this application, such routes could be prevented from being advertised in routing domains where they are required (subtle denial or service) or they could be advertised into routing domains where they shouldn't be advertised (routing vulnerability). Security considerations for the base OSPF protocol are covered in [RFC2328] and [RFC5340]. The YANG modules specified in this document define a schema for data that is designed to be accessed via network management protocols such as NETCONF [RFC6241] or RESTCONF [RFC8040]. The lowest NETCONF layer is the secure transport layer, and the mandatory-to-implement secure transport is Secure Shell (SSH) [RFC6242]. The lowest RESTCONF layer is HTTPS, and the mandatory-to-implement secure transport is TLS [RFC8446]. The NETCONF Access Control Model (NACM) [RFC8341] provides the means to restrict access for particular NETCONF or RESTCONF users to a pre- configured subset of all available NETCONF or RESTCONF protocol operations and content. The following data nodes defined in the YANG module that are writable/creatable/deletable (i.e., config true, which is the default). The modifications to these data nodes without proper protection can have a negative effect on network operations. /ospf:ospf/ospf:areas/ospf:area/ospf:interfaces/ospf:interface/ local-prefix-admin-tags /ospf:ospf/ospf:areas/ospf:area/ospf:ranges/ospf:range/admin-tags Some of the readable data nodes in this YANG module may be considered sensitive or vulnerable in some network environments. Exposure of the OSPF link state database may be useful in mounting a Denial-of- Service (DoS) attacks. These are the readable data nodes: /ospf:ospf/ospf:areas/ospf:area/ospf:interfaces/ospf:interface/ local-prefix-admin-tags Lindem, et al. Expires 20 June 2025 [Page 16] Internet-Draft OSPF Administrative Tags December 2024 /ospf:ospf/ospf:areas/ospf:area/ospf:ranges/ospf:range/admin-tags /prefix-admin-tag-sub-tlv 9. IANA Considerations The following values should be allocated from the "OSPF Extended Prefix TLV Sub-TLV" Registry [RFC7684]: * TBD1 - Administrative Tag Sub-TLV The following values should be allocated from the "OSPFv3 Extended- LSA Sub-TLV" Registry [RFC8362]: * TBD2 - Administrative Tag Sub-TLV The following values should be allocated from the "OSPFv3 SRv6 Locator LSA Sub-TLVs" Registry [RFC9513]: * TBD3 - Administrative Tag Sub-TLV The IANA is requested to assign one new URI from the IETF XML registry ([RFC3688]). Authors are suggesting the following URI: URI: urn:ietf:params:xml:ns:yang:ietf-ospf-admin-tags Registrant Contact: The IESG. XML: N/A, the requested URI is an XML namespace This document also requests one new YANG module name in the YANG Module Names registry ([RFC6020]) with the following suggestion : name: ietf-ospf-admin-tags namespace: urn:ietf:params:xml:ns:yang:ietf-ospf-admin-tags prefix: ospf-admin-tags reference: RFC XXXX 10. Acknowledgments The authors of RFC 5130 [RFC5130] are acknowledged since this document draws upon both the IS-IS specification and deployment experience. The text in Section 4 is adopted from RFC 5130. Thanks to Donnie Savage for his comments and questions. Thanks to Ketan Talaulikar for his comments and providing the BGP-LS text. Lindem, et al. Expires 20 June 2025 [Page 17] Internet-Draft OSPF Administrative Tags December 2024 Thanks to Tony Przygienda and Les Ginsberg for discussions on tag selection. Thanks to Russ White for his Routing Directorate review. Thanks to Bruno Decraene and Changwang Lin for working group last call comments. Thanks to Gunter van de Velde for has AD review and commments. 11. 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, . [RFC2328] Moy, J., "OSPF Version 2", STD 54, RFC 2328, DOI 10.17487/RFC2328, April 1998, . [RFC3688] Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688, DOI 10.17487/RFC3688, January 2004, . [RFC5340] Coltun, R., Ferguson, D., Moy, J., and A. Lindem, "OSPF for IPv6", RFC 5340, DOI 10.17487/RFC5340, July 2008, . [RFC6020] Bjorklund, M., Ed., "YANG - A Data Modeling Language for the Network Configuration Protocol (NETCONF)", RFC 6020, DOI 10.17487/RFC6020, October 2010, . [RFC6241] Enns, R., Ed., Bjorklund, M., Ed., Schoenwaelder, J., Ed., and A. Bierman, Ed., "Network Configuration Protocol (NETCONF)", RFC 6241, DOI 10.17487/RFC6241, June 2011, . [RFC6242] Wasserman, M., "Using the NETCONF Protocol over Secure Shell (SSH)", RFC 6242, DOI 10.17487/RFC6242, June 2011, . [RFC7684] Psenak, P., Gredler, H., Shakir, R., Henderickx, W., Tantsura, J., and A. Lindem, "OSPFv2 Prefix/Link Attribute Advertisement", RFC 7684, DOI 10.17487/RFC7684, November 2015, . Lindem, et al. Expires 20 June 2025 [Page 18] Internet-Draft OSPF Administrative Tags December 2024 [RFC7950] Bjorklund, M., Ed., "The YANG 1.1 Data Modeling Language", RFC 7950, DOI 10.17487/RFC7950, August 2016, . [RFC8040] Bierman, A., Bjorklund, M., and K. Watsen, "RESTCONF Protocol", RFC 8040, DOI 10.17487/RFC8040, January 2017, . [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, May 2017, . [RFC8341] Bierman, A. and M. Bjorklund, "Network Configuration Access Control Model", STD 91, RFC 8341, DOI 10.17487/RFC8341, March 2018, . [RFC8362] Lindem, A., Roy, A., Goethals, D., Reddy Vallem, V., and F. Baker, "OSPFv3 Link State Advertisement (LSA) Extensibility", RFC 8362, DOI 10.17487/RFC8362, April 2018, . [RFC8446] Rescorla, E., "The Transport Layer Security (TLS) Protocol Version 1.3", RFC 8446, DOI 10.17487/RFC8446, August 2018, . [RFC9129] Yeung, D., Qu, Y., Zhang, Z., Chen, I., and A. Lindem, "YANG Data Model for the OSPF Protocol", RFC 9129, DOI 10.17487/RFC9129, October 2022, . [RFC9513] Li, Z., Hu, Z., Talaulikar, K., Ed., and P. Psenak, "OSPFv3 Extensions for Segment Routing over IPv6 (SRv6)", RFC 9513, DOI 10.17487/RFC9513, December 2023, . [RFC9552] Talaulikar, K., Ed., "Distribution of Link-State and Traffic Engineering Information Using BGP", RFC 9552, DOI 10.17487/RFC9552, December 2023, . [RFC9587] Lindem, A., Palani, S., and Y. Qu, "YANG Data Model for OSPFv3 Extended Link State Advertisements (LSAs)", RFC 9587, DOI 10.17487/RFC9587, June 2024, . 12. Informative References Lindem, et al. Expires 20 June 2025 [Page 19] Internet-Draft OSPF Administrative Tags December 2024 [RFC3101] Murphy, P., "The OSPF Not-So-Stubby Area (NSSA) Option", RFC 3101, DOI 10.17487/RFC3101, January 2003, . [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, . [RFC5130] Previdi, S., Shand, M., Ed., and C. Martin, "A Policy Control Mechanism in IS-IS Using Administrative Tags", RFC 5130, DOI 10.17487/RFC5130, February 2008, . [RFC8340] Bjorklund, M. and L. Berger, Ed., "YANG Tree Diagrams", BCP 215, RFC 8340, DOI 10.17487/RFC8340, March 2018, . Authors' Addresses Acee Lindem (editor) LabN Consulting, L.L.C. 301 Midenhall Way Cary, NC 27513 United States of America Email: acee.ietf@gmail.com Peter Psenak Cisco Systems Apollo Business Center Mlynske nivy 43 Bratislava 821 09 Slovakia Email: ppsenak@cisco.com Yingzhen Qu Futurewei Technologies 2330 Central Expressway Santa Clara, CA 95050 United States of America Email: yingzhen.ietf@gmail.com Lindem, et al. Expires 20 June 2025 [Page 20]