



idr                                                              T. Tong
Internet-Draft                                              China Unicom
Intended status: Standards Track                                   D. Li
Expires: 3 September 2026                            Tsinghua University
                                                                 N. Geng
                                                                  Huawei
                                                                 N. Wang
                                                            China Unicom
                                                               S. Zhuang
                                                                  Huawei
                                                                 J. Zhao
                                                            China Unicom
                                                            2 March 2026


     Advertising SAV Rule-related Information using BGP Link-State
                   draft-tong-idr-bgp-ls-sav-rule-04

Abstract

   This document proposes extensions to the BGP Link-State protocol for
   advertising Source Address Validation (SAV) rule-related information.

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
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   Drafts is at https://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
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   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on 3 September 2026.

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.



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   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
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   provided without warranty as described in the Revised BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Requirements Language . . . . . . . . . . . . . . . . . .   3
   2.  BGP-LS NLRI Advertisement for SAV Rule-related Information  .   3
     2.1.  SAV Rule NLRIs  . . . . . . . . . . . . . . . . . . . . .   3
     2.2.  SAV Rule Descriptors TLVs . . . . . . . . . . . . . . . .   4
       2.2.1.  Interface Name TLV  . . . . . . . . . . . . . . . . .   5
       2.2.2.  Interface Group TLV . . . . . . . . . . . . . . . . .   5
       2.2.3.  SAV Prefix TLV  . . . . . . . . . . . . . . . . . . .   6
   3.  BGP-LS Attribute for SAV Mode . . . . . . . . . . . . . . . .   6
   4.  BGP-LS Attribute for SAV Actions  . . . . . . . . . . . . . .   7
   5.  Procedures  . . . . . . . . . . . . . . . . . . . . . . . . .   8
   6.  Manageability Considerations  . . . . . . . . . . . . . . . .   9
   7.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   9
     7.1.  "BGP-LS NLRI-Types" registry  . . . . . . . . . . . . . .   9
     7.2.  "BGP-LS SAV Rule Descriptors TLVs" registry . . . . . . .   9
     7.3.  "BGP-LS SAV Mode Attribute TLV" registry  . . . . . . . .   9
   8.  Security Considerations . . . . . . . . . . . . . . . . . . .   9
   9.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   9
     9.1.  Normative References  . . . . . . . . . . . . . . . . . .   9
     9.2.  Informative References  . . . . . . . . . . . . . . . . .  10
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  11

1.  Introduction

   Source Address Validation (SAV) is an effective method to mitigate
   source address spoofing attacks.  It is typically deployed at network
   edges, such as edge routers or Autonomous System Border Routers
   (ASBRs).  Currently, various intra-domain and inter-domain SAV
   mechanisms ([RFC3704], [RFC8704], [I-D.ietf-sidrops-bar-sav],
   [I-D.geng-idr-bgp-savnet]) exist, where SAV rules can be generated
   based on information advertised by routing protocols (such as OSPF,
   OSPFv3, IS-IS, BGP, etc.).  The SAV rules on a router are dynamically
   constructed according to the topology (including source prefixes) of
   subnets or Autonomous Systems (AS) connected to it.

   To facilitate SAV rule monitoring, attack traceback, and service
   anomaly analysis, it is critical to dynamically and in real time
   obtain SAV rule-related information for source prefixes associated
   with the subnets or AS connected to routers.  The BGP Link-State
   (BGP-LS) protocol [RFC9552] can efficiently collect link-state and



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   trafiic engineering information from networks.  This document
   proposes extensions to BGP-LS to support the collection of SAV
   rule-related information from routers.  For the purpose of
   advertising SAV rules within BGP-LS advertisements, two new NLRIs
   called SAV Rule NLRIs are proposed for IPv4 and IPv6, respectively.

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.  BGP-LS NLRI Advertisement for SAV Rule-related Information

   The "Link-State NLRI" defined in [RFC9552] is extended to carry the
   SAV rule-related information.  The format of "Link-State NLRI" is
   defined in [RFC9552] as follows:

       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
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |            NLRI Type          |     Total NLRI Length         |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                                                               |
       //                  Link-State NLRI (variable)                 //
       |                                                               |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                         Figure 1: Link-State NLRI

   This document defines two new NLRI Types known as IPv4 SAV Rule NLRI
   and IPv6 SAV Rule NLRI (values are TBD) for the advertisement of SAV
   rule-related information.

2.1.  SAV Rule NLRIs

   This document defines SAV Rule NLRI Types with their common format as
   shown in the following figure:











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      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
      +-+-+-+-+-+-+-+-+
      |  Protocol-ID  |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                           Identifier                          |
      +                           (8 octets)                          +
      |                                                               |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      //            Local Node Descriptors TLVs (variable)            //
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      //            SAV Rule Descriptors TLVs (variable)             //
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                      Figure 2: BGP-LS SAV Rule NLRI

   The fields are defined as follows:

   *  Protocol-ID: Specifies the source of SAV rules in this NLRI.
      Protocol-ID values defined in [RFC9552][RFC9086] can be reused.

   *  Identifier: An 8 octet value as defined in [RFC9552].

   *  Local Node Descriptors TLV: Contains Node Descriptors for the
      nodes storing SAV rules.  This is a mandatory TLV in SAV Rule
      NLRIs.  The Type is 256.  The length of this TLV is variable.  The
      value contains one or more Node Descriptor sub-TLVs defined in
      [RFC9552].

   *  SAV Rule Descriptors TLVs: There can be one or more SAV Rule
      Descriptors TLVs for carrying SAV rules.

2.2.  SAV Rule Descriptors TLVs

   The SAV Rule Descriptor field is a set of TLV triplets.  SAV Rule
   Descriptors TLVs identify a set of SAV rules having the same set of
   valid interfaces as defined in
   [I-D.ietf-savnet-general-sav-capabilities].  The following TLVs are
   valid as SAV Rule Descriptors in the SAV Rule NLRI:

       +-------------+---------------------+----------+
       |   TLV Code  | Description         |  Length  |
       |    Point    |                     |          |
       +-------------+---------------------+----------+
       |     TBD     | Interface Name      | variable |
       |     TBD     | Interface Group     |    4     |
       |     TBD     | SAV Prefix          | variable |
       +-------------+---------------------+----------+



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                     Figure 3: SAV Rule Descriptor TLVs

2.2.1.  Interface Name TLV

   An Interface Name TLV is used to identify one valid interface of the
   source prefixes carried in SAV Prefix TLVs.  The format of Interface
   Name TLV is as follows:

        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            |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       //                     Interface Name    (variable)            //
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                       Figure 4: Interface Name TLV

   There can be zero, one or more Interface Name TLVs in the SAV Rule
   Descriptor field.

2.2.2.  Interface Group TLV

   An Interface Group TLV is to identify a group of valid interfaces of
   the source prefixes carried in SAV Prefix TLVs.  The format of
   Interface Group TLV is as follows:

       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            |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       //                       Interface Group (4 octets)            //
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                       Figure 5: Interface Group TLV

   The Interface Group value can have either a local meaning or a global
   meaning.  On the one hand, it can be a local interface property on
   the target routers, and the meaning of it depends on the
   configurations of network administrator
   [I-D.ietf-idr-flowspec-interfaceset].  On the other hand, a global
   meaning Group Identifier field carries an AS number, which represents
   all the interfaces connected to the neighboring AS with the AS
   number.  [I-D.geng-idr-flowspec-sav]

   Interface Group value can also be an Interface ID for identifying a
   specific interface.



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   There can be zero, one or more Interface Group TLVs in the SAV Rule
   Descriptor field.  Interface Group TLVs can be used together with
   Interface Name TLVs.

   When there is neither an Interface Name TLV nor an Interface Group
   TLV, the source prefixes carried in SAV Prefix TLVs are considered
   valid for all the interfaces on the router.

2.2.3.  SAV Prefix TLV

   A SAV Prefix TLV carries one IP address prefix (IPv4 or IPv6).  The
   format of SAV Prefix TLV is as follows:

       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            |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       | Prefix Length | IP Prefix (variable)                         //
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                          Figure 6: SAV Prefix TLV

   There can be one or more SAV Prefix TLVs in the SAV Rule Descriptor
   field.  The IPv4 SAV Prefix TLVs will only appear in the IPv4 SAV
   Rule NLRI, and The IPv6 SAV Prefix TLVs are only for the IPv6 SAV
   Rule NLRI

   There can be more than one SAV mechanisms based on the same source
   (identified by Protocol-ID).  In order to distinguish the different
   sources of rules in a more fine-grained manner, the Type field needs
   to be allocated for multiple values, and each value identifies a
   specific SAV mechanism based on the same source identified by
   Protocol-ID.

3.  BGP-LS Attribute for SAV Mode

   The BGP-LS Attribute, an optional and non-transitive BGP Attribute,
   is used to carry the validation mode information of SAV rules {I-
   D.ietf-savnet-general-sav-capabilities}. The following SAV Mode
   Attribute TLV is defined for the BGP-LS Attribute associated with a
   SAV Rule NLRI:









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      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            |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |M  |  Reserved |
     +-+-+-+-+-+-+-+-+

                           Figure 7: SAV Mode TLV

   The SAV Mode TLV carries a Mode field (The "M" field is shown in the
   figure and occupies two bits) describing the validation mode of SAV.

   *  When M field is set to 00, the mode is IBA-SAV: interface-based
      prefix allowlist.  The NLRI carries the source prefixes and
      interfaces.  Only the carried prefixes are valid on the carried
      interfaces, and any other prefixes are invalid on these
      interfaces.

   *  When M field is set to 01, the mode is IBB-SAV: interface-based
      prefix blocklist.  The NLRI carries the source prefixes and
      interfaces.  Only the carried prefixes are invalid on the carried
      interfaces, and any other prefixes are valid on these interfaces.

   *  When M field is set to 10, the mode is PBA-SAV: prefix-based
      interface allowlist.  The NLRI carries the source prefixes and
      interfaces.  Only the carried interfaces are valid for the carried
      prefixes, and any other interfaces are invalid for those prefixes.
      Any other prefixes will not be validated.

   *  When M field is set to 11, the mode is PBB-SAV: prefix-based
      interface blocklist.  The NLRI carries the source prefixes and
      interfaces.  Only the carried interfaces are invalid for the
      carried prefixes, and any other interfaces are valid for those
      prefixes.  Any other prefixes will not be validated.

4.  BGP-LS Attribute for SAV Actions

   SAV actions in this document adopt the traffic filtering actions
   defined in [RFC8955] and [RFC8956].

   Traffic filtering actions defined in [RFC8955] include traffic-rate-
   bytes, traffic-rate-packets, traffic-action, rt-redirect, and
   traffic-marking, which are applicable to IPv4 and IPv6.  Rt-redirect-
   ipv6 is a new traffic filtering action defined in [RFC8956], which is
   applicable to IPv6.  The encapsulation formats of SAV actions are
   consistent with the encapsulation formats defined in [RFC8955] and
   [RFC8956].



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   A SAV rule may match multiple SAV actions, and there may be conflicts
   among these SAV actions.  Section 7.7 of [RFC8955] describes the
   conflicts among Traffic filtering actions.

5.  Procedures

   SAV rules only exist on the routers running SAV mechanisms/protocols
   and the controller, these routers are usually access routers or
   boundary routers.  This document describes extensions to the BGP-LS
   NLRI.  The Routers running SAV mechanisms/protocols establish BGP-LS
   sessions with the controller respectively to report multi-sourced SAV
   rules.

                     +--------------------------+
                     |        Controller        |
                     +--------------------------+
                        /                    \
                       /                      \  BGP-LS advertisements for SAV Rule NLRIs
+---------------------/------------------------\--------------+    +---------------+
|   AS100            /                          \             |    |   AS200       |
|                +---------+                +---------+       |    |  +---------+  |
|  access router | Router1 |                | Router2 |-------|----|--| Router3 |  |
|                +---------+                +---------+       |    |  |+--------+  |
|                 /      \                  boundary router   |    |               |
|                /        \                                   |    +---------------+
|               /          \                                  |
|              /            \                                 |
|      +---------+         +---------+                        |
|      | Subnet1 |         | Subnet2 |                        |
|      +---------+         +---------+                        |
|                                                             |
+-------------------------------------------------------------+

          Figure 8: Advertisement of SAV Rules using BGP-LS

   Based on Figure 8, the process of reporting SAV rules via BGP-LS is
   described as follows: Step 1: R1 and R2 run SAV mechanism/protocol,
   and generate multi-sourced SAV rules.  R1 serves as an access router
   connecting local subnets, while R2 functions as a border router
   peering with external AS.  These routers running SAV mechanisms can
   exchange SAV specific information between them.  Step 2: R1 and R2
   respectively establish BGP-LS sessions with the controller.  Step 3:
   R1 and R2 generate BGP-LS advertisements for the SAV Rule NLRIs.
   Step 4: R1 and R2 report multi-sourced SAV rules to the controller
   through the sav rule NLRIs (as defined in Section 2).  This enables
   the controller to monitor and manage multi-sourced SAV rules.





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6.  Manageability Considerations

   The Existing BGP operational and management procedures apply to this
   document.  No new procedures are defined in this document.  The
   considerations as specified in [RFC9552] apply to this document.

7.  IANA Considerations

   This section describes the code point allocation by IANA for this
   document.

7.1.  "BGP-LS NLRI-Types" registry

   This document requests assigning code-points from the registry for
   SAV Rule NLRIs:

   +------+---------------------------+
   | Type | NLRI Type                 |
   +------+---------------------------+
   | TBD  | IPv4 SAV Rule NLRI        |
   | TBD  | IPv6 SAV Rule NLRI        |
   +------+---------------------------+

7.2.  "BGP-LS SAV Rule Descriptors TLVs" registry

   This document requests assigning code-points from the registry for
   BGP-LS SAV Rule Descriptors TLVs based on Figure 3.

7.3.  "BGP-LS SAV Mode Attribute TLV" registry

   This document requests assigning a code-point from the registry for
   the BGP-LS SAV Mode attribute TLV.

8.  Security Considerations

   Procedures and protocol extensions defined in this document do not
   affect the base BGP security model.  See [RFC6952] for details.  The
   security considerations of the base BGP-LS specification as described
   in [RFC9552] also apply.

9.  References

9.1.  Normative References

   [RFC9552]  Talaulikar, K., Ed., "Distribution of Link-State and
              Traffic Engineering Information Using BGP", RFC 9552,
              DOI 10.17487/RFC9552, December 2023,
              <https://www.rfc-editor.org/info/rfc9552>.



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   [I-D.ietf-savnet-general-sav-capabilities]
              Huang, M., Cheng, W., Li, D., Geng, N., and L. Chen,
              "General Source Address Validation Capabilities", Work in
              Progress, Internet-Draft, draft-ietf-savnet-general-sav-
              capabilities-02, 10 October 2025,
              <https://datatracker.ietf.org/doc/html/draft-ietf-savnet-
              general-sav-capabilities-02>.

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,
              <https://www.rfc-editor.org/info/rfc2119>.

   [RFC8174]  Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
              2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
              May 2017, <https://www.rfc-editor.org/info/rfc8174>.

9.2.  Informative References

   [I-D.geng-idr-bgp-savnet]
              Geng, N., Li, Z., Tan, Z., Liu, and D. Li, "BGP Extensions
              for Source Address Validation Networks (BGP SAVNET)", Work
              in Progress, Internet-Draft, draft-geng-idr-bgp-savnet-05,
              18 September 2025, <https://datatracker.ietf.org/doc/html/
              draft-geng-idr-bgp-savnet-05>.

   [I-D.ietf-sidrops-bar-sav]
              Sriram, K., Lubashev, I., and D. Montgomery, "Source
              Address Validation Using BGP UPDATEs, ASPA, and ROA (BAR-
              SAV)", Work in Progress, Internet-Draft, draft-ietf-
              sidrops-bar-sav-08, 20 October 2025,
              <https://datatracker.ietf.org/doc/html/draft-ietf-sidrops-
              bar-sav-08>.

   [I-D.ietf-idr-flowspec-interfaceset]
              Litkowski, S., Simpson, A., Patel, K., and J. Haas,
              "Applying BGP flowspec rules on a specific interface-set",
              Work in Progress, Internet-Draft, draft-ietf-idr-flowspec-
              interfaceset-06, 2 September 2025,
              <https://datatracker.ietf.org/doc/html/draft-ietf-idr-
              flowspec-interfaceset-06>.

   [I-D.geng-idr-flowspec-sav]
              Geng, N., Li, D., tongtian124, and M. Huang, "BGP Flow
              Specification for Source Address Validation", Work in
              Progress, Internet-Draft, draft-geng-idr-flowspec-sav-06,
              17 October 2025, <https://datatracker.ietf.org/doc/html/
              draft-geng-idr-flowspec-sav-06>.



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Authors' Addresses

   Tian Tong
   China Unicom
   Beijing
   China
   Email: tongt5@chinaunicom.cn


   Dan Li
   Tsinghua University
   Beijing
   China
   Email: tolidan@tsinghua.edu.cn


   Nan Geng
   Huawei
   Beijing
   China
   Email: gengnan@huawei.com


   Nan Wang
   China Unicom
   Beijing
   China
   Email: wangn161@chinaunicom.cn


   Shunwan Zhuang
   Huawei
   Beijing
   China
   Email: zhuangshunwan@huawei.com


   Jing Zhao
   China Unicom
   Beijing
   China
   Email: zhaoj501@chinaunicom.cn









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