Le 30 sept. 2011 à 19:20, Ole Troan a écrit : > Remi, > >>>>> in the general case there is no way to guarantee that a host doesn't pick >>>>> the same IID. >>>> >>>> Well, "no guarantee"... unless a safe way of doing it is specified! >>>> And this is already the case with 4rd-addmapping-01. >>>> (If you would keep doubts after a careful check, please share your >>>> understanding.) >>>> >>>> The modified format discussed in Beijing with Xing Li, Congxiao Bao, and >>>> Wojciech Dec, to be documented soon, will have the same property. >>> >>> there are no guarantees, and no safe way of doing that. >>> there is no enforcement of global uniqueness of interface ids. >>> e.g. the use of longer than /64 prefixes, manual configuration. >>> you have a high probability of it being unique. and as long as it is only >>> used for pretty printing and troubleshooting, then do you care? >> >> Still, the Modified EUI-64 format of RFC 4291 has been designed to ensure >> unicity of these Universal-scope IIDs. >> True, a user can manually configure an EUI-64 IID that he shouldn't. The >> confusion that results is then his responsibility. >> The same applies if a host behind a 4rd CE configures a 4rd IID: it won't be >> reachable from the Internet. >> >> Possibility of misconfiguration MUST NOT be a reason to give up specifying >> formats that work in absence of misconfigurations (as done with the modified >> EUI-64 format of RFC 4291). > > that's a property that was highly speculative 15 years ago when it was > specified and a property that has never been verified. > but, let me turn the question around. what are the requirements for a > globally unique interface-id? how is it going to be used? > both for encapsulation and translation?
In both cases, the CE node can recognize 4rd packets, and process them as such, without preempting any IID value that might be a legitimate value for a host behind the CE. > is it expected that routers have to make forwarding decisions on an > interface-id? No. Ordinary routers are concerned with IIDs only on destination links but here, like with 6to4 and 6rd, there is no last link where the IID is exploited. RD > > cheers, > Ole _______________________________________________ Softwires mailing list [email protected] https://www.ietf.org/mailman/listinfo/softwires
