Extension for BMP Peer Interface
draft-lin-grow-bmp-peer-interface-02

GROW                                                              C. Lin
Internet-Draft                                      New H3C Technologies
Intended status: Standards Track                                  Y. Liu
Expires: 7 January 2027                                     China Mobile
                                                           M. Srivastava
                                              Hewlett Packard Enterprise
                                                             P. Francois
                                                               M. Younsi
                                                               INSA-Lyon
                                                             6 July 2026

                    Extension for BMP Peer Interface
                  draft-lin-grow-bmp-peer-interface-02

Abstract

   This document proposes extending BMP to allow BMP messages with the
   per-peer header to carry interface information for the established
   peer session, especially in order to distinguish parallel link-local
   and unnumbered BGP peers established based on distinct 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
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   This Internet-Draft will expire on 7 January 2027.

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   Please review these documents carefully, as they describe your rights

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   and restrictions with respect to this document.  Code Components
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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   2
   3.  Solutions . . . . . . . . . . . . . . . . . . . . . . . . . .   3
     3.1.  BMPv4 TLV Extension . . . . . . . . . . . . . . . . . . .   3
       3.1.1.  Rx Peer-Address TLV Extension . . . . . . . . . . . .   3
       3.1.2.  Tx Peer-Interface TLV . . . . . . . . . . . . . . . .   4
     3.2.  Per-Peer Header Extension . . . . . . . . . . . . . . . .   5
       3.2.1.  BMP Peer Type Definition  . . . . . . . . . . . . . .   6
       3.2.2.  New Per-Peer Header Format  . . . . . . . . . . . . .   6
   4.  Operational Considerations  . . . . . . . . . . . . . . . . .   7
   5.  Security Considerations . . . . . . . . . . . . . . . . . . .   7
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   7
   7.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   7
     7.1.  Normative References  . . . . . . . . . . . . . . . . . .   7
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   8

1.  Introduction

   When BGP establishes a peer relationship using a link-local address
   or unnumbered address, the local outgoing interface must be specified
   for the relationship to be established successfully.  In other words,
   parallel link-local or unnumbered BGP peers can only be distinguished
   by interface information.

   However, the peer information in a BMP message does not include peer
   interface information, making it impossible to distinguish which BGP
   peer the reported BMP message originated from or sent to in scenarios
   involving parallel link-local or unnumbered BGP peers.

   This document introduces two approaches that enables BMP messages
   with the per-peer header to carry interface information for the
   established peer session.

2.  Terminology

   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.

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3.  Solutions

   This section presents two BMP extensions designed to convey peer
   interface information within BMP messages: one extends the BMPv4 TLV
   structure, while the other introduces an extension to the BMP per-
   peer header.

3.1.  BMPv4 TLV Extension

   In order to report the BMP messages that need to be distinguished
   through peer interface information, this section extends "Rx Peer-
   Address TLV" defined in [I-D.ietf-grow-bmp-loc-peer], and defines a
   new BMPv4 [I-D.ietf-grow-bmp-tlv] TLV.  This new BMPv4 TLV is
   designed to convey interface information of the peer to which the
   monitored path is sent and is therefore named the "Tx Peer-Interface
   TLV".

3.1.1.  Rx Peer-Address TLV Extension

   This section introduces the extension of the "Rx Peer-Address TLV" to
   carry the peer interface information.  The structure of the "Rx Peer-
   Address TLV" is defined in [I-D.ietf-grow-bmp-loc-peer] and 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
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |        Type (2 octets)        |       Length (2 octets)       |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |G|      Index (15 bits)        | Address Type  |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     ~                    Rx Peer Address (variable)                 |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                     Figure 1: Rx Peer-Address TLV

   This document defines new four address types, as follows:

   *  Address Type = 4: IPv6 Address with Interface ID.  The "Rx Peer
      Address" is the 16 bytes IPv6 Address of the peer, followed by an
      interface ID of a variable size S.  The "Length" is thus set to 1
      + 16 + S.

   *  Address Type = 5: IPv6 Address with Interface Name.  The "Rx Peer
      Address" is the 16 bytes IPv6 Address of the peer, followed by an
      interface name of a variable size S, encoded in UTF-8 without
      specific termination characters.  The "Length" is thus set to 1 +
      16 + S.

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   *  Address Type = 6: IPv4 Address with Interface ID.  The "Rx Peer
      Address" is the 4 bytes IPv4 Address of the peer, followed by an
      interface ID of a variable size S.  The "Length" is thus set to 1
      + 4 + S.

   *  Address Type = 7: IPv4 Address with Interface Name.  The "Rx Peer
      Address" is the 4 bytes IPv4 Address of the peer, followed by an
      interface name of a variable size S, encoded in UTF-8 without
      specific termination characters.  The "Length" is thus set to 1 +
      4 + S.

   The "Rx Peer-Address TLV" could be used for Local-RIB, Adj-RIB-In,
   and Adj-RIB-Out.

   For Local-RIB, this TLV is only used for BMP Route Monitoring
   Messages.

   For Adj-RIB-In, this TLV can be used for BMP Route Monitoring
   Messages, BMP Route Mirroring Messages, and BMP Stats Reports
   Messages, and the "Index" field MUST be ignored.

   For Adj-RIB-Out, this TLV can be used for BMP Route Monitoring
   Messages and BMP Route Mirroring Messages.

   For Non-Local-RIB peers, this TLV can be used for BMP Peer Down
   Notification Messages and Peer Up Notification Messages, and the
   "Index" field also MUST be ignored.

3.1.2.  Tx Peer-Interface TLV

   This section introduces the new "Tx Peer-Interface TLV" to carry the
   peer interface information.  The TLV structure is illustrated in
   Figure 2.

      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 (2 octets)        |       Length (2 octets)       |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |    Subtype    |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     ~                  Tx Peer Interface (variable)                 |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                       Figure 2: Tx Peer-Interface TLV

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   The "Tx Peer-Interface TLV" type is TBD1.  The value of the TLV is
   the "Subtype" code (1 octet) followed by the "Tx Peer Interface"
   information used to establish the related peer session.  The "Length"
   field is one (for the "Subtype" field) plus the length of the "Tx
   Peer Interface" field.

   The "Subtype" field is defined, as shown below:

   *  Subtype = 1: IPv6 Address with Interface ID.  The "Tx Peer
      Interface" is the 16 bytes IPv6 Address of the peer, followed by
      an interface ID of a variable size S.  The "Length" is thus set to
      1 + 16 + S.

   *  Subtype = 2: IPv6 Address with Interface Name.  The "Tx Peer
      Interface" is the 16 bytes IPv6 Address of the peer, followed by
      an interface name of a variable size S, encoded in UTF-8 without
      specific termination characters.  The "Length" is thus set to 1 +
      16 + S.

   *  Subtype = 3: IPv4 Address with Interface ID.  The "Tx Peer
      Interface" is the 4 bytes IPv4 Address of the peer, followed by an
      interface ID of a variable size S.  The "Length" is thus set to 1
      + 4 + S.

   *  Subtype = 4: IPv4 Address with Interface Name.  The "Tx Peer
      Interface" is the 4 bytes IPv4 Address of the peer, followed by an
      interface name of a variable size S, encoded in UTF-8 without
      specific termination characters.  The "Length" is thus set to 1 +
      4 + S.

   The "Tx Peer-Interface TLV" could only be used for Adj-RIB-Out.

   For Adj-RIB-Out, this TLV can be used for BMP Route Monitoring
   Messages and BMP Route Mirroring Messages, and BMP Stats Reports
   Messages.

   For Non-Local-RIB peers, this TLV can also be used for BMP Peer Down
   Notification Messages and Peer Up Notification Messages.

   For BMP Peer Down Notification Messages and Peer Up Notification
   Messages, only one of the "Tx Peer-Interface TLV" and "Rx Peer-
   Address TLV" is allowed to carry the peer interface information.

3.2.  Per-Peer Header Extension

   To enable the distinction of BMP messages based on peer interfaces,
   this section defines new BMP peer types and extends the BMP per-peer
   header accordingly.

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3.2.1.  BMP Peer Type Definition

   The peer types are defined as follows:

   *  Peer Type = TBD1 (RECOMMENDED value 4): Global Instance Interface
      Peer.

   *  Peer Type = TBD2 (RECOMMENDED value 5): RD Instance Interface
      Peer.

   BMP messages using the peer types defined in this document MUST
   include peer interface information in the per-peer header.

3.2.2.  New Per-Peer Header Format

   For new BMP peer types defined in this document, this section defines
   a new per-peer header, called the "Interface Per-Peer Header".  It is
   defined according to per-peer header of [RFC7854], as shown in
   Figure 2.

     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
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |   Peer Type   |  Peer Flags   |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |         Peer Distinguisher (present based on peer type)       |
     |                                                               |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                 Peer Address (16 bytes)                       |
     ~                                                               ~
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |         Peer Interface Index (present based on peer type)     |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                           Peer AS                             |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                         Peer BGP ID                           |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                    Timestamp (seconds)                        |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                  Timestamp (microseconds)                     |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                Figure 2: Interface Per-Peer Header Format

   Compared with per-peer header of [RFC7854], the Peer Interface Index
   is added to indicate the interface used to establish BGP peers.
   Other fields are defined in Section 4.2 of [RFC7854] and Section 4 of
   [RFC8671].

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4.  Operational Considerations

   This document introduces two solutions designed to convey peer
   interface information within BMP messages: one is the BMPv4 TLV
   extension, and the other is the BMP per-peer header extension.  The
   BMP per-peer header extension could apply to BMPv3 and BMPv4
   [I-D.ietf-grow-bmp-tlv], but the interface is identified only by its
   interface index.  If the interface name must be needed to identify a
   interface, the BMP per-peer header extension cannot be used; only the
   BMPv4 TLV extension can be used.  The BMPv4 TLV extension applies
   exclusively to BMPv4.  And when reporting BMP Local RIB messages
   requires peer interface information, the BMPv4 TLV extension MUST be
   used.

   When a BMP monitoring station needs to distinguish between parallel
   BGP sessions established over different interfaces (e.g., using link-
   local or unnumbered addresses), the BMPv4 TLV extension or BMP per-
   peer header extension SHOULD be included in the relevant BMP
   messages.

   When a BMP sender generates a BMP message that requires
   distinguishing peers by interface, the BMP message SHOULD include the
   BMPv4 TLV extension or BMP per-peer header extension.  The BMP
   receiver needs to be able to resolve this TLV extension or this per-
   peer header extension to correctly associate the BMP message with the
   BGP peer on a specific interface.

   BMP receivers with older versions that do not support this TLV or
   this new peer type MAY ignore unknown TLVs or peer types, but this
   MAY prevent them from correctly identifying parallel interface-based
   peers.

5.  Security Considerations

   TBD

6.  IANA Considerations

   TBD

7.  References

7.1.  Normative References

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   [I-D.ietf-grow-bmp-loc-peer]
              Francois, P., Younsi, M., and P. Lucente, "BMP Loc-RIB:
              Peer address", Work in Progress, Internet-Draft, draft-
              ietf-grow-bmp-loc-peer-02, 17 October 2025,
              <https://datatracker.ietf.org/doc/html/draft-ietf-grow-
              bmp-loc-peer-02>.

   [I-D.ietf-grow-bmp-tlv]
              Lucente, P., Gu, Y., Younsi, M., and P. Francois, "BMP v4:
              Extended TLV Support for BGP Monitoring Protocol (BMP)",
              Work in Progress, Internet-Draft, draft-ietf-grow-bmp-tlv-
              20, 2 March 2026, <https://datatracker.ietf.org/doc/html/
              draft-ietf-grow-bmp-tlv-20>.

   [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>.

   [RFC7854]  Scudder, J., Ed., Fernando, R., and S. Stuart, "BGP
              Monitoring Protocol (BMP)", RFC 7854,
              DOI 10.17487/RFC7854, June 2016,
              <https://www.rfc-editor.org/info/rfc7854>.

   [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>.

   [RFC8671]  Evens, T., Bayraktar, S., Lucente, P., Mi, P., and S.
              Zhuang, "Support for Adj-RIB-Out in the BGP Monitoring
              Protocol (BMP)", RFC 8671, DOI 10.17487/RFC8671, November
              2019, <https://www.rfc-editor.org/info/rfc8671>.

Authors' Addresses

   Changwang Lin
   New H3C Technologies
   Beijing
   China
   Email: linchangwang.04414@h3c.com

   Yisong Liu
   China Mobile
   32 Xuanwumen West Street
   Beijing
   Xicheng District, 100053
   China

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   Email: liuyisong@chinamobile.com

   Mukul Srivastava
   Hewlett Packard Enterprise
   Email: mukul.srivastava@hpe.com

   Pierre Francois
   INSA-Lyon
   Villeurbanne
   France
   Email: pierre.francois@insa-lyon.fr

   Maxence Younsi
   INSA-Lyon
   Villeurbanne
   France
   Email: maxence.younsi@insa-lyon.fr

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