[143058] in North American Network Operators' Group
Re: "L3DSR -- Overcoming Layer 2 Limitations of Direct Server
daemon@ATHENA.MIT.EDU (Jan Schaumann)
Tue Jul 26 23:07:11 2011
Date: Tue, 26 Jul 2011 23:06:11 -0400
From: Jan Schaumann <jschauma@netmeister.org>
To: Matt Hite <lists@beatmixed.com>
In-Reply-To: <CAFOdRHKnnEGVu6o6fuuQtA36EE2vXdQKm_+MMnPVZOk+TU5dGg@mail.gmail.com>
Cc: nanog@nanog.org
Errors-To: nanog-bounces+nanog.discuss=bloom-picayune.mit.edu@nanog.org
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Matt Hite <lists@beatmixed.com> wrote:
> Hi, Jan. It's a great presentation and I really love your approach.
> However, I am curious -- why was IP-in-IP not pursued? I know the
> presentation mentioned the MTU issue, but your final solution seemed
> full of enough pitfalls itself (ie -- lots of cooperation from
> numerous groups, people, and processes) that raising MTU in your
> network might be an easier proposition. Thought you might have went
> into it a bit in the video, that's all. Any insight?
We have come to the conclusion that Path MTU Discovery on the internet
at large... doesn't work so well. :-)
With IP-in-IP or GRE, our MTU increases, so either we keep the MTU the
same (to the outside) and declare (internally) our own largest packet to
be smaller than 1500 or change the MTU (internally) to be larger than
1500 (to account for the overhead). Either way, we end up with an MTU
that's different between at least two of the client, the LB and our
server.
The idea of using the DSCP bit then seemed to be more reasonable to us.
-Jan
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