So I just wasted a few hours of my life trying to bully some ASRs into forming an iBGP relationship on an AS that neither was "officially" a member of. Something like this:
router bgp 65000 neighbor 10.10.10.1 remote-as 65010 neighbor 10.10.10.1 local-as 65010
Not for production use, mind you... just trying to PoC some different configurations in a lab that's really too small to do what I need to do, so I'm trying to cheat certain things.
In any case, this *mostly* works. Was testing certain RR setups and stuff just fine. Right up until they're no longer adjacent, when they fail entirely. After dicking around with MTUs for a while, I finally just grabbed some pcaps and see both of these damned routers sending their SYNACKs with a TTL of 1. The SYNs were sent with 255, and in sessions that *were* adjacent, once they got going all the keepalives, etc were with TTL of 255.
Is this just a "stupid edge case no one supports anyway, so it's broken" thing? Or is it "actually expressly forbidden and should definitely never work"?
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