Re: [Softwires] 4rd Address Mapping - version-01

[Ole Troan <[e-mail]>]

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.

you didn't quite answer my question.
let us get back to the starting point. what are you trying to achieve by having a special IID?

cheers,
Ole