Hi Erik, > -----Original Message----- > From: Erik Nordmark [mailto:[email protected]] > Sent: Thursday, April 09, 2015 8:05 AM > To: Xuxiaohu; [email protected] > Subject: Re: [nvo3] Encapsulation considerations > > On 4/7/15 7:15 PM, Xuxiaohu wrote: > > Hi Erik, > > > > As it has said in the draft : "... We later expanded the scope somewhat to > consider how the encapsulations would play with MPLS "transport", which is > important because SFC and BIER seem to target being dependent of the > underlying "transport"...", it would be necessary to consider the first nibble > issue for those encapsulations which may be transported over MPLS. More > specifically, for those encapsulations which may be directly encapsulated > further > with an MPLS header, they must not start with the value 4 (IPv4) or the value > 6 > (IPv6) in the first nibble. Otherwise, they would be mistakenly interpreted > as IP > payloads by transit LSRs and therefore be subjected to ECMP and potential > packet misordering. > > Xiaohu, > Good point. > > But I couldn't tell from the emails on the BIER list whether the constraints > on the > first nibble value is a strict requirement in all cases, or whether it is > conditional > on something (and if so, what is the condition).
The conditions that I have thought of include: 1) the encapsulation is sensitive to packet misordering; 2) the encapsulation may be transported over an MPLS PSN; 3) LSRs within that MPLS PSN may use the contents of the MPLS payload to select the ECMP path. Best regards, Xiaohu > Once I know that answer we can definitely add some text pointing out the > issue. > > Thanks, > Erik > > > > > Best regards, > > Xiaohu > > > >> -----Original Message----- > >> From: Erik Nordmark [mailto:[email protected]] > >> Sent: 2015年3月26日 5:01 > >> To: [email protected] > >> Subject: [nvo3] Encapsulation considerations > >> > >> > >> I presented part of this at the most recent NVO3 interim meeting.The > >> full > > 12 > >> areas of considerations where presented at RTGWG earlier this week. > >> The draft is > >> http://datatracker.ietf.org/doc/draft-rtg-dt-encap/ > >> and the slides are at > >> http://www.ietf.org/proceedings/92/slides/slides-92-rtgwg-8.pdf > >> > >> There is probably additional things in there to consider for NVO3, > >> and > > advice > >> that can be reused to make it easier to move NVO3 forward. > >> > >> Regards, > >> Erik > >> > >> > >> > > > > _______________________________________________ > > nvo3 mailing list > > [email protected] > > https://www.ietf.org/mailman/listinfo/nvo3 > > _______________________________________________ nvo3 mailing list [email protected] https://www.ietf.org/mailman/listinfo/nvo3
