[e2e] "PMTUD using options" draft

[Stefan Savage]

FWIW, there's a nice little paper that Ramesh Govindan and Vern Paxson did
trying to measure slow-path effects for ttl exceeded generation.

http://www.icir.org/vern/papers/fsd-pam-02.pdf
 
The high-bit is that they indeed find that this isn't a common issue on the
modern Internet.

- Stefan
-----Original Message-----
From: end2end-interest-admin at postel.org
[mailto:end2end-interest-admin at postel.org] On Behalf Of RJ Atkinson
Sent: Thursday, February 12, 2004 8:35 AM
To: Michael Welzl
Cc: end2end-interest at postel.org
Subject: Re: [e2e] "PMTUD using options" draft


On Feb 12, 2004, at 10:49, Michael Welzl wrote:
> Some things may really make sense as an IP option, but
> you usually can't propose them in the IETF because a
> number of people tell you that this is unrealistic
> because of slow path processing, which makes everything
> at least 700 times slower.

I agree that people say this.  Such people generally are
not people who have experience building modern routers.
The main reason I mentioned this on-list here is to try
to spread the word that the common-belief is myth not
reality (at least for a while now).

> No proof, no numbers, no measurements.

That is a common frustration with IETF.  I like the
idea of experimental computing science very much.

> The idea was just to change that. If I know that IP
> options typically lead to an approximate additional
> delay of about 7%, I may be able to judge wheter a
> proposal based on IP options makes sense or not.
>
> I mean, I can't measure everything ... for instance,
> what if I flood a router with packets carrying options?
> Will the result be the same?

	If one has a hardware-based router that is designed to
perform packet processing at wire-rate, one would expect
that the flooding would not matter (unless/until the affected
interface itself filled up).

Cheers,

Ran