[BEHAVE] Fwd: IPv6 hosts sending <1280 byte packets

Iljitsch van Beijnum <iljitsch@muada.com> Sun, 07 February 2010 19:39 UTC

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From: Iljitsch van Beijnum <iljitsch@muada.com>
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Date: Sun, 07 Feb 2010 20:40:06 +0100
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Subject: [BEHAVE] Fwd: IPv6 hosts sending <1280 byte packets
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Ben Stasiewics has done some testing to see if hosts actually respond with a fragment header after a < 1280 too big message, and the results are surprising.

Looks like we can't depend on hosts implementing this correctly.

Begin forwarded message:

> From: Ben Stasiewicz <ben@wand.net.nz>
> Date: 7 februari 2010 19:39:08 GMT+01:00
> To: mtu@psc.edu
> Cc: Matthew Luckie <mjl@wand.net.nz>
> Subject: Re: IPv6 hosts sending <1280 byte packets [was RE: RRG discussion of SEAL, IPTM - and my critique of RFC4821]

> On 29/01/10 08:40, Dan Wing wrote:
>> Ben, would it be possible to conduct a test to see how hosts react to PTB
>> smaller than 1280?

> I conducted such a test and found that 299 (43.46%) of the 688
> IPv6-capable web servers that I tested did include an IPv6 fragmentation
> header in their response packets after they were sent an ICMPv6 PTB
> message specifying an MTU < 1280 bytes. The other 389 (56.54%) did not.

> I am happy to answer any questions about the test.