> -----邮件原件----- > 发件人: Xuxiaohu > 发送时间: 2013年11月27日 9:47 > 收件人: 'Thomas Narten'; [email protected] > 主题: 答复: [nvo3] TTL handling in an L3 service > > > > > -----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.
In addition, I can't imagine a scenario where routing protocol messages need to be transported across a Layer3 overlay as well in the NVO3 context. Xiaohu > 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
