Thanks for the answers.
On 2/23/10 3:53 AM, "Ole Troan" <[email protected]> wrote: > 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
