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Date: Thu, 21 Jul 2005 12:17:36 +0200
From: Martin Zielinski <mz@seh.de>
Subject: [users:00080] Re: PATH MTU tests in IPv6 Ready Phase 2 tool
To: users@tahi.org
Cc: sdukas@spectracomcorp.com
Message-Id: <42DF7640.2000107@seh.de>
In-Reply-To: <20050721131915.4c487115.akisada@64translator.com>
References: <8830683A4191A3439C34E10BDEB1BD00189F7F@exchange.MIROGE> <20050721131915.4c487115.akisada@64translator.com>
X-Mail-Count: 00080

Hi Stavros,

I'm playing around to make a device with this kernel-version pass the 
phase 2 tests...

To pass the pmtu-tests 9 + 10, I simply changed in

ip6_output.c - ip6_build_xmit() :

if (pktlength <= mtu) into
if (pktlength < mtu)

Problem was, that the 1280 packet did not get a fragment header.
I'm just at the beginning and do not see if there are side-effects.

Bye,

Martin

Yukiyo Akisada wrote:
> Hi, Stavros.
> 
> RFC 1981 - Path MTU Discovery for IPv6 - says,
> 
>     4. Protocol Requirements
>     ------------------------------------------------------------------------
>     238    A node MUST NOT reduce its estimate of the Path MTU below the IPv6
>     239    minimum link MTU.
>     240
>     241       Note: A node may receive a Packet Too Big message reporting a
>     242       next-hop MTU that is less than the IPv6 minimum link MTU.  In that
>     243       case, the node is not required to reduce the size of subsequent
>     244       packets sent on the path to less than the IPv6 minimun link MTU,
>     245       but rather must include a Fragment header in those packets [IPv6-
>     246       SPEC].
>     ------------------------------------------------------------------------
> 
> v6LC.4.1.6 Part A and B is verifying this behavior.
> Test scripts expect that NUT doesn't reduce PMTU less than 1280 byte,
> but NUT uses Fragment Header.
> 
> Thanks,
> 
> 
> On Fri, 8 Jul 2005 11:36:58 -0400
> "Stavros Dukas" <sdukas@spectracomcorp.com> wrote:
> 
> 
>>Hi,
>>
>>            I am running the IPv6 ready Phase 2 conformance tests and
>>getting 2 fails in the Path MTU Discovery tests. Tests 9 and 10 (MTU
>>size 0x0 and MTU size 512 respectively). I'm running the tests on a
>>2.4.29 USAGI patched kernel. I think it is due to my host machine not
>>resetting its PMTU size to react to the Packet Too Big message or
>>setting it to the wrong value. Can someone help me with this? 
>>
>>Thank you in advance,
>>
>>Stavros Dukas
> 
> 
> 
> ------------------------------------------------------------------------
> Yukiyo Akisada <akisada@64translator.com>
> 
> 


-- 
Martin Zielinski             mz@seh.de
Software Development
SEH Computertechnik GmbH     www.seh.de