Software Version Capability for BGP

Abstract

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

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

1. Introduction

In modern data center designs, we tend to have conventional routers participating in the routing process. And the fleet of routers has different versions of routing daemon. This means that knowing which versions of the routing daemons are running the various routers in the network can be a crucial factor in quickly identifying the root cause of any protocol or network problems.¶

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

Information about the version of the routing daemon could also be exchanged in protocols such as LLDP and CDP. However, in containerized environments, it is very hard and not recommended to exchange this information between background processes. Therefore, and to help minimize operational costs, it is helpful to exchange the routing daemon information between BGP peers directly.¶

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.¶

Capabilities advertisements with BGP are defined in [RFC5492]. They utilize the BGP Capabilities Optional Parameter that contains 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 switch to enable or disable its use, and that switch MUST be off by default.¶

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 [RFC5492].¶

The triple for the Software Version Capability is as follows:¶

Capability Code¶

• 75¶

Capability Length¶

• 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 is the limit to allow other capabilities as much space as they require.¶
• Capability Length is a one-octet unsigned binary integer that contains the length of the Capability Value field in octets.¶

Capability Value¶

• The Capability Value field is encoded in UTF-8 [RFC3629]. 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 of 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¶

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 daemon at a different version installed. 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.¶

References

Appendix A. Implementation Report

According to RFC 7942, "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 implementation.¶

GoBGP implementation.¶

freeRouter implementation.¶

ExaBGP implementation.¶

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)
  ...

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

  :~# 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"
  }