Le 2012-02-08 à 13:43, Satoru Matsushima a écrit : > On 2012/02/07, at 17:53, Rémi Després wrote: > >> >> Le 2012-02-07 à 17:35, Satoru Matsushima a écrit : >> >>> On 2012/02/07, at 16:46, Rémi Després wrote: >>> >>> --snip-- >>> >>>>>> >>>>>>>>> I think that operators who already deploy such dual-stack network is >>>>>>>>> supposed that they have address mapping table, >>>>>>>> >>>>>>>> I would rather suppose that ISPs that have added IPv6-prefix >>>>>>>> delegation, say /56s, to an existing IPv4 network did it without >>>>>>>> mixing their IPv6 plan with their IPv4 prefixes. >>>>>>>> I am ready, however, to look seriously at individual cases where >>>>>>>> choices were different. >>>>>>> >>>>>>> Basically provision MAP CE is based on its delegated IPv6 prefix in >>>>>>> concept. It is opposed to your case but technically possible. >>>>>> >>>>>> >>>>>>> Now I concern that it requires much complicated CE implementation. >>>>>> >>>>>> All what is required is that CEs set an address bit if hub&spoke >>>>>> topology is required. >>>>>> >>>>> >>>>> So how CE decide to set the bit, and when the CE figure it out? >>>> >>>> The CE knows it must set this bit if, and only if, it received at >>>> initialization a Topology-variant parameter set to Hub&spoke (sec 4.1). >>>> In this case, the CE sets bit 79 to 1 in IPv6 destination addresses of all >>>> packets it sends. >>>> >>>> BTW, this bit should better, for clarity, be given a name, e.g. bit B >>>> meaning To-BR bit (or whatever better idea one could propose). I plan to >>>> do it in the next version. >>>> >>> >>> So you mean that if the hub&spoke bit is set, a CE derives /112 IPv6 prefix >>> as 4rd end point from IPv4 address which is already assigned. >> >> >> If the CE is delegated a prefix shorter than /64, it isn't concerned with >> the To-BR bit. >> If it is delegated a /112, it finds its IPv4 address inom it. >> It then must set the To-BR bit, in its outgoing IpV6 destinations, iff the >> Topology variant is Hub&spoke. >> > > As you described in your draft, if a CE is delegated /112 IPv6 prefix, the CE > automatically form itself for H&S mode and extract a non-sharing IPv4 address > from the /112 prefix.
Hub&spoke vs Mesh is independent from /112. Otherwise, yes, a CE always derives its IPv4 address when it receives a /112 matching the default mapping rule. > >> >>> Otherwise, a CE derives its IPv4 address from delegated IPv6 prefix. right? >> >> The CE always derives its 4rd prefix from its delegated IPv6 prefix, based >> on the Mapping rule that has the longest match. >> > > So you mean that it is only specific case of which if the extracted IPv4 > address is same with an address assigned to a dual-stack interface on the CE, > the default route on the CE is forced to the BR, Yes, by setting the ToBR bit. > and keep that address on the dual-stack interface as NAPT source address. Is > that what you request to 4rd-U CE implementation? I think so. > It also requires operator to manage specific /112 route for each CE that > means IPv4 host routes are injected to the operator's IPv6 routing table > that's what Ole already pointed out. Well, an ISP has assigned that has assigned fixed IPv4 addresses, and wants to keep them while moving to IPv6-only routing needs, one way or another, to reflect IPv4 routes in IPv6. > I agree with Ole that I'm doubt it could be widely acceptable technique for > operators. It is useful for ISPs that have this use case, even if there aren't many, and in any case creates no harm for others. It is a way to encourage IPv6 routing for ISPs that don't want to maintain DS routing. RD > > cheers, > --satoru > _______________________________________________ Softwires mailing list [email protected] https://www.ietf.org/mailman/listinfo/softwires
