[58346] in North American Network Operators' Group
Re: PMTU and Broken Servers
daemon@ATHENA.MIT.EDU (Richard A Steenbergen)
Thu May 8 13:20:19 2003
Date: Thu, 8 May 2003 13:17:58 -0400
From: Richard A Steenbergen <ras@e-gerbil.net>
To: Mikael Abrahamsson <swmike@swm.pp.se>
Cc: Leo Bicknell <bicknell@ufp.org>, nanog@merit.edu
In-Reply-To: <Pine.LNX.4.44.0305081901550.6232-100000@uplift.swm.pp.se>
Errors-To: owner-nanog-outgoing@merit.edu
On Thu, May 08, 2003 at 07:04:18PM +0200, Mikael Abrahamsson wrote:
>
> On Thu, 8 May 2003, Leo Bicknell wrote:
>
> > Could you define newer? My limited testing with 12.0S and 12.2something
> > shows both returing MTU can't be set on a tunnel interface.
>
> You cannot change the MTU of the tunnel, but you can change the "ip mtu"
> of the tunnel. I've done this on 7200 and 1600 that are running IOSes that
> are at least a year old. The feature is at least 2-3 years old, because
> that's the first time I encountered it.
>
> The router will do re-assembly on the tunnel level to be able to transfer
> a 1500 byte sized IP packet non-fragmented.
Be warned, while fragmentation follows some form of fast path, reassembly
is process switched. A beefy 7206 will fragment 300Mbps easily, but will
reassemble around 30Mbps.
--
Richard A Steenbergen <ras@e-gerbil.net> http://www.e-gerbil.net/ras
GPG Key ID: 0xF8B12CBC (7535 7F59 8204 ED1F CC1C 53AF 4C41 5ECA F8B1 2CBC)
