Software Version Capability for BGP
draft-abraitis-bgp-version-capability-18

Inter-Domain Routing                                         D. Abraitis
Internet-Draft                                                 Hostinger
Intended status: Informational                          7 September 2025
Expires: 11 March 2026

                  Software Version Capability for BGP
                draft-abraitis-bgp-version-capability-18

Abstract

   In this document, we introduce a new BGP capability that allows the
   advertisement of a BGP speaker's routing software version.

   This BGP capability is an optional advertisement.  Implementations
   are not required to advertise the version nor to process received
   advertisements.

Status of This Memo

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   provisions of BCP 78 and BCP 79.

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   This Internet-Draft will expire on 11 March 2026.

Copyright Notice

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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Specification of Requirements . . . . . . . . . . . . . . . .   2
   3.  Software Version Capability . . . . . . . . . . . . . . . . .   3
     3.1.  Capabilities Length Overflow  . . . . . . . . . . . . . .   4
   4.  Operation . . . . . . . . . . . . . . . . . . . . . . . . . .   5
   5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   5
   6.  Security Considerations . . . . . . . . . . . . . . . . . . .   5
   Acknowledgements  . . . . . . . . . . . . . . . . . . . . . . . .   6
   References  . . . . . . . . . . . . . . . . . . . . . . . . . . .   6
     Normative References  . . . . . . . . . . . . . . . . . . . . .   6
   Appendix A.  Implementation Report  . . . . . . . . . . . . . . .   7
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .   8

1.  Introduction

   In modern data center designs, conventional routers participating in
   routing.  These routers may have different versions of routing
   software.  Knowing which versions of the routing software that are
   running on the various routers in the network can be a crucial factor
   in quickly identifying the root cause of protocol or network
   problems.

   This document specifies a BGP capability that carries the routing
   software version.  This BGP capability is a optional.
   Implementations are not required to advertise their software version
   nor to process it on receipt.

   Information about the version of the routing software could also be
   exchanged in protocols such as LLDP and CDP.  However, in
   containerized environments, it is difficult and not recommended to
   exchange this information between background processes.  To assist in
   minimizing operational costs, it is helpful to exchange the routing
   software versions between BGP peers directly.

2.  Specification of Requirements

   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.  Software Version Capability

   Although this document is not an IETF Standards Track document, it
   makes use of the terminology from BCP 14 in order to clearly state
   the implementation behaviors.

   BGP capability advertisement is defined in [RFC5492].  BGP
   Capabilities contain one or more triples <Capability Code, Capability
   Length, Capability Value>.  This document defines a new BGP
   capability, the Software Version Capability, with Capability Code 75
   and Capability Length and Capability Value as described below.

   The inclusion of the Software Version Capability is OPTIONAL.  If an
   implementation supports the inclusion of the capability, the
   implementation MUST include a configuration option to enable or
   disable its use, and MUST default to disabled.

   The Software Version Capability is intended for environments where
   more visibility is needed for troubleshooting purposes.  It is NOT
   RECOMMENDED for use outside a single Autonomous System, or a set of
   Autonomous Systems under a common administration.

   An implementation that does not recognize or support the Software
   Version Capability but receives one must ignore it, as described in
   Section 3 of [RFC5492].

   The triple for the Software Version Capability is as follows:

   Capability Code

      75

   Capability Length

      Capability Length is a one-octet unsigned binary integer that
      contains the length of the Capability Value field in octets.

      The Capability Length for the Software Version Capability MUST be
      greater than zero.  A value of zero SHALL be treated as an
      encoding error and the Capability MUST be ignored.

      The Capability Length SHOULD be no greater than 64.  This length
      leaves space for other capabilities.

   Capability Value

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      The Capability Value field is the software version encoded as a
      UTF-8 [RFC3629] string.  It is unstructured data and can be
      formatted in any way that the implementor decides.  The string is
      not null-terminated.

   Version:

      The Version field MUST be encoded using UTF-8.  A receiving BGP
      speaker MUST NOT interpret invalid UTF-8 sequences.

      The value consists of one identifier, which identifies the
      software and its significant version.  Software version identifier
      consists of a product and optional product version.

      identifier = product ["/" product-version]

      A sender SHOULD limit generated product identifiers to what is
      necessary to identify the product; a sender MUST NOT generate
      advertising or other nonessential information within the product
      identifier.  A sender SHOULD NOT generate information in product-
      version that is not a version identifier (i.e., successive
      versions of the same product name ought to differ only in the
      product-version portion of the product identifier).

      Example:

      frrouting/8.4.2, ios/12.5.1, junos/12.1

3.1.  Capabilities Length Overflow

   As defined in [RFC5492] the total length of capabilities that can be
   carried by the BGP Capabilities Optional Parameter is 255 bytes.  If
   an implementation is constructing a BGP Capabilities Optional
   Parameter and its length exceeds 255 bytes, there is not enough space
   for other more important capabilities.

   Implementations of this specification are REQUIRED Extended Optional
   Parameters Length for BGP OPEN Message support as defined in
   [RFC9072].

   A rogue node can prevent the proper operation of a BGP session, or
   the advertisement of other Capabilities, by not excluding the
   Software Version Capability as required in Section 3.1.  This risk is
   equivalent to a rogue node simply not advertising a specific
   Capability and is not new to BGP.

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4.  Operation

   The Software Version Capability MUST only be used for displaying the
   version of a BGP speaker's router daemon to make troubleshooting
   easier.

   Consider a group of routers each with a number of upstream nodes, and
   suppose that each router has a different operating system and
   different routing software at a different installed version.
   Assuming that a specific feature is not working or that there is a
   bug which has not been fixed in a particular version of the code,
   knowledge of the routing daemon versions would allow an operator to
   quickly identify the pattern of which versions are affected.

   Enabling (i.e., turning on) this capability requires bouncing all
   existing BGP sessions and the feature MUST be explicitly configured
   before an implementation advertizes the Software Version Capability.

5.  IANA Considerations

   IANA has assigned capability number 75 for the Software Version
   Capability described in this document.  This registration is in the
   BGP Capability Codes registry.

                  +=======+=============================+
                  | Value |         Description         |
                  +=======+=============================+
                  |   75  | Software Version Capability |
                  +-------+-----------------------------+

                    Table 1: Software Version Capability

6.  Security Considerations

   The Software Version Capability should be treated as sensitive
   information: it could be easier for an attacker to exploit the system
   if they know the specific software version and manufacturer of a BGP
   speaker.  This information could be gathered by inspecting BGP OPEN
   messages that carry the Software Version Capability defined in this
   document.  Furthermore, this knowledge may facilitate a number of
   social-engineering attacks.

   Modifying the information advertised by a router might lead to
   attacks including bogus software upgrades and also might mask the
   causes of faults in the network.

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   Users of this mechanism should be aware that unless a transport that
   provides integrity is used for the BGP session in question, the
   Software Version Capability can be forged.  Unless a transport that
   provides confidentiality is used, the Version Capability could be
   snooped by an attacker.  These issues are common to any BGP message
   but may be of greater interest in the context of this extension as
   explained above.  Refer to the related considerations in [RFC4271]
   and [RFC4272].

   Users of this mechanism should consider applying data minimization
   practices as outlined in Section 6.1 of [RFC6973], as appropriate
   within the deployment context.

   Sensitive information leaks can be minimized by using the Generalized
   TTL security mechanism [RFC5082] or firewalls to filter out TCP 179
   port from untrusted networks.  This capability should be enabled per
   neighbor, thus limiting the disclosure of sensitive information to
   trusted neighbors.

Acknowledgements

   Thanks to Alvaro Retana, Jakob Heitz, Robert Raszuk, Adrian Farrel,
   John Scudder, Jeffrey Haas, Enke Chen for the review, discussions and
   input to the draft.

References

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,
              <https://www.rfc-editor.org/info/rfc2119>.

   [RFC3629]  Yergeau, F., "UTF-8, a transformation format of ISO
              10646", STD 63, RFC 3629, DOI 10.17487/RFC3629, November
              2003, <https://www.rfc-editor.org/info/rfc3629>.

   [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,
              <https://www.rfc-editor.org/info/rfc4271>.

   [RFC4272]  Murphy, S., "BGP Security Vulnerabilities Analysis",
              RFC 4272, DOI 10.17487/RFC4272, January 2006,
              <https://www.rfc-editor.org/info/rfc4272>.

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   [RFC5082]  Gill, V., Heasley, J., Meyer, D., Savola, P., Ed., and C.
              Pignataro, "The Generalized TTL Security Mechanism
              (GTSM)", RFC 5082, DOI 10.17487/RFC5082, October 2007,
              <https://www.rfc-editor.org/info/rfc5082>.

   [RFC5492]  Scudder, J. and R. Chandra, "Capabilities Advertisement
              with BGP-4", RFC 5492, DOI 10.17487/RFC5492, February
              2009, <https://www.rfc-editor.org/info/rfc5492>.

   [RFC6973]  Cooper, A., Tschofenig, H., Aboba, B., Peterson, J.,
              Morris, J., Hansen, M., and R. Smith, "Privacy
              Considerations for Internet Protocols", RFC 6973,
              DOI 10.17487/RFC6973, July 2013,
              <https://www.rfc-editor.org/info/rfc6973>.

   [RFC7942]  Sheffer, Y. and A. Farrel, "Improving Awareness of Running
              Code: The Implementation Status Section", BCP 205,
              RFC 7942, DOI 10.17487/RFC7942, July 2016,
              <https://www.rfc-editor.org/info/rfc7942>.

   [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>.

   [RFC9072]  Chen, E. and J. Scudder, "Extended Optional Parameters
              Length for BGP OPEN Message", RFC 9072,
              DOI 10.17487/RFC9072, July 2021,
              <https://www.rfc-editor.org/info/rfc9072>.

Appendix A.  Implementation Report

   According to [RFC7942], "This will allow reviewers and working groups
   to assign due consideration to documents that have the benefit of
   running code, which may serve as evidence of valuable experimentation
   and feedback that have made the implemented protocols more mature".

   FRRouting (https://github.com/FRRouting/frr/commit/
   c4257900c4ca320117bcd1f88b7f036e0c8f7fcb) implementation.

   GoBGP (https://github.com/osrg/gobgp/pull/2622/
   commits/15f9d5c64c98d1db273cc45e95fcc11843fba4b5) implementation.

   freeRouter (https://github.com/mc36/freeRtr/commit/
   eb5d3490aec220ad8bfcbf1f439669bd27845199) implementation.

   ExaBGP (https://github.com/Exa-Networks/exabgp/pull/1223/commits/
   d21e432c98ec9cbe1de2e471ecf7326170d7f176) implementation.

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   Below is an example from the FRRouting and GoBGP implementations
   showing both the received and advertised Software Version Capability:

     :~# vtysh -c 'show ip bgp summary failed'
     ...
     Neighbor EstdCnt DropCnt ResetTime Reason
     ens192         3       3  00:00:35 Waiting for peer OPEN (n/a)
     ens224         3       3  00:01:12 Waiting for NHT (frrouting/7.2)
     eth0           3       3  00:00:14 Neighbor deleted (frrouting/7.3)
     ...

                                  Figure 1

           software-version:   advertised and received
             Local:
                GoBGP/3.10.0
             Remote:
                FRRouting/8.5-dev-MyOwnFRRVersion-gdc92f44a4

                                  Figure 2

     :~# vtysh -c 'show ip bgp neighbors 198.51.100.1 json' \
     > | jq '."198.51.100.1".neighborCapabilities.versions'
     {
       "advertisedVersion": "frrouting/7.2",
       "receivedVersion": "frrouting/7.3"
     }

                                  Figure 3

Author's Address

   Donatas Abraitis
   Hostinger
   Email: donatas.abraitis@gmail.com

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