Thu, Sep 08, 2022 at 08:13:33AM -0700, Randy Bush: > > During some IPv6 numbering discussions at work today, someone had a > > question that I hadn't really considered before. How to choose 32-bit > > router IDs for IPv6-only routers. > > arbitrary 32 bit number unique in the autonomous system. even in an > ipv4 world it does not need to match any configured interface address.
A question Dorian and I discussed but never answered is, how are open collisions handled if two speakers, presumably an external AS, happen to have the RID? Which would be possible if an AS chose their RIDs randomly or intentionally used low numbers (eg: 0/24) to attract traffic as a result of the BGP path selection process. 4172: Based on the value of the BGP Identifier, a convention is established for detecting which BGP connection is to be preserved when a collision occurs. The convention is to compare the BGP Identifiers of the peers involved in the collision and to retain only the connection initiated by the BGP speaker with the higher-valued BGP Identifier. Easily answered by testing, and could yield fun results (bugs). I presume both would (should) close and reconnect later, possibly repeatedly before success, thereby delaying session establishment.
