Re: Simplified NAT-PT

[Brian E Carpenter <brian.e.carpenter@gmail.com>]

Hello again,

On 2008-02-07 16:34, Hiroshi MIYATA wrote:
> Thanks Brian for your comment.
> 
> 
> 
> On 2008/02/07, at 11:05, Brian E Carpenter wrote:
> 
>> Miyata-san,
>>
>> I haven't completely studied this yet, but I have two
>> quick comments.
>>
>>>   The prefix PREFIX::/96 is advertised in the IPv6 network by the
>>>   NAT-PT gateway, and packets addressed to this PREFIX will be routed
>>>   to the NAT-PT gateway. The pre-configured PREFIX only needs to be
>>>   routable within the IPv6 network and as such it can be any routable
>>>   prefix that the network administrator chooses.
>>
>> This seems to assume that the NAT-PT is at the boundary between
>> a closed IPv6 routing realm (where it's OK to advertise a /96)
>> and the IPv4 network. What happens if someone needs to put
>> a NAT-PT between a closed IPv4 routing realm and the open
>> IPv6 network?
> 
> I think advertising /64 is enough.
> Prefix for routing should be 64-bit.
> And following 32-bit is indicator used by host to detect the translator.
> Sorry, my description maybe confusable.

But you can't advertise a /64 to the Internet either...

>>
>>
>>>
>>>   The following 32-bit, represented as IDENT MUST be an value assigned
>>>   by IANA to indicate that translator would exist in the path.
>>>   More requirement for IDENT is described in Chapter 13.
>>
>> Why is this useful?
> 
> IDENT can help end-node to know the existence of translator.
> And it must be unique.
> Then the end-node can have some options.
> Put dialog to user, quit the session, search other address, etc...

I don't understand the value of these options. If you wanted the
upper layer protocol to calculate "correct" checksums, you could
play tricks with these "IDENT" bits to achieve that, I suppose.

    Brian

> If the end-node does not have function to detect the translator,
> like existing implementation, it would connect to the address.
> 
> Regards,
> 
> ...miyata
> 
> 
>>
>>
>>    Brian
>>
>>
> 
>