Re: What flexibility do 6to4 NAT have with address formats?

Brian E Carpenter <brian.e.carpenter@gmail.com> Wed, 14 October 2009 01:38 UTC

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Date: Wed, 14 Oct 2009 14:37:56 +1300
From: Brian E Carpenter <brian.e.carpenter@gmail.com>
Organization: University of Auckland
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To: Christian Huitema <huitema@microsoft.com>
Subject: Re: What flexibility do 6to4 NAT have with address formats?
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On 2009-10-14 14:09, Christian Huitema wrote:
>>> The second question regards the uniqueness of host
>>> identifiers. Suppose we define the address used for stateless
>>> translation as: 32 bit "provider" prefix, 32 bit IPv4
>>> address, and a constant identifier, either 0 or the "checksum
>>> neutrality" value, which is only a function of the provider
>>> prefix. Suppose now that for some reason there are two "IPv4
>>> addressed" hosts on the same link, e.g. because many servers
>>> are located in the same server room. The two hosts will have
>>> different addresses, in different 64 bit subnets, but they
>>> will also have different host identifiers. Is that OK?
>> Why wouldn't it be OK? I can't see why it's a question.
>> The normal expectation is that different hosts have different
>> IIDs so I am curious why this matters.
> 
> I just realize I made "typo". I meant to say " The two hosts will have
> different addresses, in different 64 bit subnets, but they will also have 
> the same host identifiers. Is that OK?

Well, that would be OK if you set U=0 as far as I can see.
It might be an odd situation, but then nobody should ever rely on
their uniqueness. It might be safer to make U=0 mandatory
for these synthetic addresses in all cases.

If you don't respect the UG bits we are asking for trouble anyway.

   Brian

What flexibility do 6to4 NAT have with address fo… Christian Huitema
Re: What flexibility do 6to4 NAT have with addres… Brian E Carpenter
RE: What flexibility do 6to4 NAT have with addres… Christian Huitema
Re: What flexibility do 6to4 NAT have with addres… Brian E Carpenter
RE: What flexibility do 6to4 NAT have with addres… Perkins, Carroll G
Re: What flexibility do 6to4 NAT have with addres… Ole Troan
RE: What flexibility do 6to4 NAT have with addres… Dunn, Jeffrey H.
RE: What flexibility do 6to4 NAT have with addres… Templin, Fred L
RE: What flexibility do 6to4 NAT have with addres… Dunn, Jeffrey H.
Re: What flexibility do 6to4 NAT have with addres… Brian E Carpenter
Re: What flexibility do 6to4 NAT have with addres… Brian Haberman