Re: [v4v6interim] Fragmentation Options in NAT6 presentation

Brian E Carpenter <brian.e.carpenter@gmail.com> Fri, 03 October 2008 23:45 UTC

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Date: Sat, 04 Oct 2008 12:46:05 +1300
From: Brian E Carpenter <brian.e.carpenter@gmail.com>
Organization: University of Auckland
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To: Hiroshi MIYATA <miyata@tahi.org>
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Cc: v4v6interim@ietf.org
Subject: Re: [v4v6interim] Fragmentation Options in NAT6 presentation
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Actually the *correct* solution is to use a method of
PMTU discovery that does not depend on ICMP.
That's the point of RFC 4821.

  Brian

On 2008-10-04 08:51, Hiroshi MIYATA wrote:
> Correct!
> 
> We have met the problem, and, yes, only the way is fragmenting
> the packet on the Translator.
> We have developed it as a optional behavior.
> 
> It may cause the argument if we state it in document, since
> it break the PMTU Discovery semantics.
> 
> But it is the fact.
> 
> Maybe it is not recommended to describe on BEHAVE documents
> as a requirement.
> But we should give the hint of this issue on the documents
> as possible problems and solution and utilization (since
> it is not recommended to use this in public service, but
> possible to be used for controllable area of the administrator.)
> 
> Regards,
> 
> ....miyata
> 
> 
> On 2008/10/04, at 3:36, Wes Beebee (wbeebee) wrote:
> 
>> Some SP's may view ICMP as an attack vector and may explicitly block
>> ICMP messages.
>>
>> In this case, the only way to get connectivity for packets that are too
>> large is to fragment.
>>
>> - Wes
>>
>> -----Original Message-----
>> From: v4v6interim-bounces@ietf.org [mailto:v4v6interim-bounces@ietf.org]
>> On Behalf Of Hiroshi MIYATA
>> Sent: Friday, October 03, 2008 5:31 AM
>> To: v4v6interim@ietf.org
>> Subject: [v4v6interim] Fragmentation Options in NAT6 presentation
>>
>> Jennings,
>>
>>
>> FYI.
>> Though it is already clearly explained by Dave, let me give you the
>> pointer.
>> The answer for your question of "Fragmentation options" is clearly
>> stated in RFC2765(SIIT) as end-to-end path MTU discovery.
>> See Section 3 and 4.
>>
>> And of course RFC1981(PMTUD) is compliant with it. ;-) Chap. 4
>>       Note: A node may receive a Packet Too Big message reporting a
>>       next-hop MTU that is less than the IPv6 minimum link MTU.  In
>> that
>>       case, the node is not required to reduce the size of subsequent
>>       packets sent on the path to less than the IPv6 minimun link MTU,
>>       but rather must include a Fragment header in those packets [IPv6-
>>       SPEC].
>>
>> It must work well. ;-)
>>
>> Regards,
>>
>> ....miyata
>> _______________________________________________
>> v4v6interim mailing list
>> v4v6interim@ietf.org
>> https://www.ietf.org/mailman/listinfo/v4v6interim
>>
> 
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