Subject: Re: can't raise in kernel pppoe0 with mtu > 1460
To: None <tech-net@NetBSD.org, port-i386@NetBSD.org>
From: Matthias Scheler <tron@zhadum.de>
List: tech-net
Date: 03/22/2005 18:15:05
In article <20050321213457.GB15496@drowsy.duskware.de>,
	Martin Husemann <martin@duskware.de> writes:
> Well, there is no officicial "good" value for clamping, this is all
> about working around broken network setups somewhere else. FWIW,
> I use MTU (which happens to be 1460 at some places for me too) - 8
> as clamping size and never noticed any problems.

That cannot work because the IP and TCP header need at least 40 bytes.
The minimum reasonable value for MSS clamping is MTU - 40. But
according to my experience it's better to MTU - 52 to leave room
for TCP options.

	Kind regards

-- 
Matthias Scheler                                  http://scheler.de/~matthias/