Re: about Wedgelayer 3.5 / Fat IP approaches

marcelo bagnulo braun wrote:
> 
> El 29/06/2004, a las 13:49, Brian E Carpenter escribió:
> 
>> Eik Nordmark wrote:
>>
>>>> what about cgas?
>>>> They are locators, so you can use them for refferals to non multi6 
>>>> apps and hosts, they allow to map from id to locators using reverse 
>>>> dns, and they are crypto in nature
>>>> seems a good candidate to me :-)
>>>
>>> A downside of CGA approaches is that they would, on a global basis,
>>> cast the /64 subnet prefix boundary in stone forever.
>>> This is different than SeND which only assumes the /64 on a single link,
>>> and one can envision SeND evolving to handle different subnet prefix 
>>> lengths
>>> over time.
>>> Different people probably have very different level of concern for
>>> "/64 forever in stone" ranging from it being a good simplification
>>> to a fatal repeat of the 8 bit IPv4 network number + 24 bit host number
>>> (before Class B and C was invented).
>>
>>
>> Good point. The /64 boundary is only "architectural" in one place, 
>> stateless
>> autoconfig, and even that is a changeable decision.
>>
>> CGAs have other downsides for multihoming, too.
>>
> 
> such as?


<chair hat off>

I really don't want to start a discussion here about cryptographic
strength, but my objection to CGAs in the multi6 context is that they
include the /48 prefix in the hash, and that is variable in multi6,
which means that the host ID changes when you change prefix. I think
that's an unfortunate property because it eliminates some possible
tricks in the ID/locator split.

    Brian