Deprecation of BGP Path Attribute values 30, 31, 129, 241, 242, and 234

It has been discovered that certain BGP Path Attribute values have been used in BGP implementations which have been deployed in the wild while not being assigned by the IANA for such usage. Unregistered usage of BGP Path Attribute values can lead to deployment problems for new technologies. The use of these unregistered values was noticed when BGP Large Communities attribute was initially assigned value 30 by IANA. It was subsequently discovered that a widely-deployed BGP-4 implementation had released code which used path attribute 30 and which applied a "Treat-as-withdraw" strategy to routes containing a valid Large Community attribute, since it was expecting a different data structure. Because these routes were dropped, early adopters of Large Communities were unreachable from parts of the Internet. As a workaround, a new Early IANA Allocation was requested. The squatting of values 30, 31, 129, 241, 242 and 243 has been confirmed by the involved vendors or through source code review.

Per this document, IANA is requested to mark values 30, 31, 129, 241, 242, and 243 as "deprecated" in the "BGP Path Attributes" registry under the "Border Gateway Protocol (BGP) Parameters" group. The marking "deprecated" meaning "use is not recommended" ().