We have a peering BGP session that keeps dropping. This is between two IPv6 peers. OPEN happens, capabilities are agreed open, and prefixes are exchanged via UPDATE messages.
Then one of the peers sends an UPDATE with ORIGIN, AS_PATH, and MP_UNREACH_NLRI attributes, which should be a valid update, much like ORIGIN, AS_PATH, and MP_REACH_NLRI. However, the Arista complains about a missing well-known attribute, and the data field is set to “3”, which indicates that it’s apparently wanting to see NEXTHOP(3). Consequently we send them a NOTIFICATION and the session drops.
Looking at the RFCs, this seems like a valid update to me (ORIGIN, AS_PATH, MP_UNREACH_NLRI). Is this perhaps a bug? Or am I missing something silly?
This is a DCS-7280SRA-48C6-M-F running 4.19.9M.