Le 7 avr. 2011 à 00:20, Lee, Yiu a écrit : > Hi Remi, > > I think I mis-read Figure 1 in your draft. As I read this, I think the > current design will completely rely on dhcp to manage the v4 prefix. Yes, > this decouples the v4 and v6 addresses, but this will add additional > operation effort on dhcp. Also, if an ISP has many small IPv4 prefixes > they want to use in 4rd, it will require to provision all of them to the > BR. This may be ok for some operators, but not all operators. > > In term of single or multiple 4over6 concentrators, I don't see people > will advertise the same PI from two far away concentrators. So the return > packet will also go back to the same (or close) concentrator. That said, I > agree that stateless is always easier for HA. I have no disagreement on > this. >
> In the end, they have pros and cons. Based on the ISP's requirements, it > is just a matter of choice. We agree. Thanks. RD > > Cheers, > /Yiu > > On 4/6/11 5:19 PM, "Rémi Després" <[email protected]> wrote: > >> Yiu, >> >> I am not sure we completely understand each other here. >> Please tell me if what I write is insufficiently clear. >> >> Le 6 avr. 2011 à 21:06, Lee, Yiu a écrit : >> >>> Hi Remi, >>> >>> On 4/6/11 10:04 AM, "Rémi Després" <[email protected]> wrote: >>> >>>> Partially agreed. >>>> - If all IPv6 customers are given the same number of IPv4 ports, 4rd >>>> doesn't imply anything on Pv6 routing., >>>> - If there are several 4over6 concentrators, there are constraints on >>>> the >>>> IPv6 routing to ensure satisfactory load sharing between them with >>>> stable >>>> routes. >>>> - Furthermore, if these concentrators are far from one another, they >>>> imply that the IPv4 backbone ensures symmetric routing so that all >>>> return >>>> traffic from a concentrator comes back to it. >>> >>> I think we are on the same page. What I meant is in the case of stateful >>> 6to4, IPv6 address won't contain any IPv4 address in the prefix. That >>> won't require coupling between the IPv4 and IPv6 prefixes. It may or may >>> not be a problem for some operators. >> >> IPv6 prefixes of 6rd don't contain IPv4 embedded addresses (they differ >> in this respect from the stateless A+P described in the aplusp draft). >> With 4rd, if all CE's get IPv6 prefixes having the same length, and are >> assigned the same number of IPv4 ports, the IPv6 routing is taken as is. >> It is only after that that one or a few mapping rules, whose parameters >> can be advertised in stateless DHCPv6, define how each CE derives its >> shared IPv4 address and port set from its IPv6 prefix. >> >>> LB is a different issue. It doesn't relate to address coupling. That >>> said, >>> it isn't so straight forward for stateless approach because it depends >>> on >>> the placement of the BR and the v6 routing to the anycast address. >> >> Routing of the IPv6 network can be reconfigured at any time without >> breaking connections. >> Load balancing can be performed without any concern for packets of each >> connection having to go to the same BR, which makes it simpler. >> >> >>> For stateful 4to6, the outgoing and incoming v4 traffic are symmetric >>> because all v4 traffic must traverse the concentrator. I don¹t see why >>> the >>> backbone has to do something special for it. >> >> If there is only one concentrator, no problem. >> But if there are several widely separated concentrators, and they are >> reachable at the same PI prefix at the border between the IPv6-only >> network and the IPv4 backbone, then there is a return path problem. >> >> RD >> >> PS: I may be able to continue tomorrow, but then will be unreachable >> until April 25. >> >> >> >> > _______________________________________________ Softwires mailing list [email protected] https://www.ietf.org/mailman/listinfo/softwires
