Deprecation of BGP OPEN Message Error subcodes 8, 9, and 10.

It has been discovered that certain BGP OPEN Message Error subcodes 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 OPEN Message Error subcodes can lead to increased difficulty when troubleshooting why BGP sessions are torn down. The use of these unregistered values was noticed when the concept of Route Leak Prevention and Detection using Roles in UPDATE and OPEN Messages was initially assigned value 8 by IANA. It was subsequently discovered that a widely-deployed BGP-4 implementation had released code which used BGP OPEN Message Error Subcode 8. As a workaround, a new Early IANA Allocation is to be requested. The squatting of values 8, 9, and 10 has been confirmed by the involved vendors or through source code review.

Per this document, IANA is requested to mark values 8, 9, and 10 as "deprecated" in the "OPEN Message Error subcodes" registry under the "Border Gateway Protocol (BGP) Parameters" group. The marking "deprecated" meaning "use is not recommended" ().