> -----邮件原件----- > 发件人: nvo3 [mailto:[email protected]] 代表 Thomas Narten > 发送时间: 2013年11月27日 0:58 > 收件人: [email protected] > 主题: [nvo3] TTL handling in an L3 service > > 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").
Hi Thomas, I think it's worthwhile to discuss the TTL handling issue associated with L3 service or L3 overlay. However, the above example (i.e., ND) is not accurate since it seems no need to transport the ND messages across a Layer3 overlay. Best regards, Xiaohu > 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 _______________________________________________ nvo3 mailing list [email protected] https://www.ietf.org/mailman/listinfo/nvo3
