[76986] in North American Network Operators' Group
Re: Broken PMTUD for . + TLD servers, was: Re: Smallest Transit MTU
daemon@ATHENA.MIT.EDU (Iljitsch van Beijnum)
Sun Jan 9 18:40:37 2005
In-Reply-To: <200501092308.j09N8F4W066527@drugs.dv.isc.org>
Cc: nanog@merit.edu
From: Iljitsch van Beijnum <iljitsch@muada.com>
Date: Mon, 10 Jan 2005 00:39:54 +0100
To: Mark Andrews <Mark_Andrews@isc.org>
Errors-To: owner-nanog-outgoing@merit.edu
On 10-jan-05, at 0:08, Mark Andrews wrote:
> Well DNS (not EDNS) is limited to 512 octets so you unless there
> are real links (not ones artificially constrained to demonstrate
> a issue) this should not be a issue in practice.
No, fortunately not. But it's still VERY wrong and it must be fixed.
> Note for IPv6 one sets IPV6_USE_MIN_MTU on the UDP socket so this
> should be a non-issue there.
In IPv6 PMTUD is handled at the IP layer so the second packet that's
too large will be fragmented at the source, so there is no issue.
