Hi. In precisely defining L3 service, one question that comes up is how is the TTL treated. That is, say NVO3 provides L3 VN service to a TS. When TSes on the VN communicate with each other, they are always using IP. What happens to the TTL in such packets?
I see several choices: a) do not decrement the TTL at all. Treat the TSes as if they were directly attached to each other (i.e., on the same link) b) Decrement by 1... c) Decrement by some random amount.. :-) Some protocols may care about TTL handling. IPv6 Neighbor Discovery, for example, requires that ND packets be dropped if they are received with a TTL other than 255 (i.e., they'd require choice a). I think some other routing protocols do the same (as a way to ignore packets from offlink "attackers"). What do tenants of an L3 service expect? Do they care (other than in cases like ND)? Can we just define L3 service as saying the TTL of tenant packets are not modified by NVO3? Any advice from L3 service providers that already provide such services today? Thomas _______________________________________________ nvo3 mailing list [email protected] https://www.ietf.org/mailman/listinfo/nvo3
