Subject: Re: can't raise in kernel pppoe0 with mtu > 1460
To: None <tech-net@NetBSD.org, port-i386@NetBSD.org>
From: Matthias Scheler <firstname.lastname@example.org>
Date: 03/22/2005 18:15:05
In article <20050321213457.GB15496@drowsy.duskware.de>,
Martin Husemann <email@example.com> 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.
Matthias Scheler http://scheler.de/~matthias/