Reinaldo, [...]
> Thanks for the answer. There seems to be some differences here that you can > help clarify in the context of anycast. > > These questions are based on the following from the draft (and section > around it) that in my reading advances an idea of fully stateless > deployment. > > "As 6rd is stateless, any BR may be used at any time. " > > In 6rd although one can use anycast, there is a need for the IGP to be > stable, correct? It cannot be fully stateless otherwise different packets > for the same (source, destination, protocol) tuple would use different BRs. > Traceroute packets with the same TTL, source and destination taking > different paths would be a subset of a more general problem. the IGP does not need to be stable. just like in a 'native' IP network you prefer that packets for the same flow follow the same path. when that doesn't happen, e.g because of link failure or IGP instability then the behaviour of 6rd packets will be just like the native IPv4 packets. the same thing happens if you withdraw the anycast route on BR failure. > But in general what are the anycast affinity requirements for such a > deployable solution? But more specifically when connection based protocols > like TCP that react to delay are used on top of it. there are of course operational issues here. and I would certainly not recommend load-balancing between BR's which are on different continents for example. > I'm familiar with the use of anycasting for DNS where request and responses > are idempotent, short-lived and over a connectionless protocol, therefore > not much an issue. > > And also use of TCP anycast as in this presentation > http://www.nanog.org/meetings/nanog37/presentations/matt.levine.pdf where > there are discussions on use and stability requirements. right, but that's for using an anycast address as a endpoint for a TCP session. here we only use anycast as a next-hop. this is not Internet-wide anycast like e.g 6to4 uses. this is all intended to be contained within an SP. where you also have tight control over the anycast advertisements in the IGP. not that I don't think this would also work in an Internet context, but then we're back to 6to4 with all its issues. cheers, Ole _______________________________________________ Softwires mailing list [email protected] https://www.ietf.org/mailman/listinfo/softwires
