Re: [v4v6interim] Fragmentation Options in NAT6 presentation

Hiroshi MIYATA <miyata@tahi.org> Sat, 04 October 2008 08:57 UTC

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From: Hiroshi MIYATA <miyata@tahi.org>
To: Brian E Carpenter <brian.e.carpenter@gmail.com>
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Date: Sat, 04 Oct 2008 17:56:35 +0900
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Subject: Re: [v4v6interim] Fragmentation Options in NAT6 presentation
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Brian,

Thanks for your input.
I will investigate it!

Cheers!

...miyata

On 2008/10/04, at 8:46, Brian E Carpenter wrote:

> 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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