Subject: Re: ADSL upstream problems on Sparc NetBSD 1.5
To: Sebastian Wain <>
From: Manuel Bouyer <>
List: tech-net
Date: 09/07/2001 18:43:01
On Thu, Sep 06, 2001 at 09:46:28PM -0400, Sebastian Wain wrote:
> Hello,
> I have an ADSL connection (using the ethernet Alcatel Speed Touch Home
> modem) and in any operating system that I used this connection  via PPTP
> (Linux, OpenBSD, NetBSD, excepted windows) there is a problem "uploading"
> information to Internet, that is sending a bulk of data from my machine to
> other on Internet (for example sending an attachment in my mail, doing a
> scp to a remote machine and so on).
> Currently the NetBSD is my firewall and it's the machine connected
> to the modem doing nat.
> I read some info about this problem on Internet, it's related to a MTU
> problem, but playing with differents hints I have not solved it.
> There is some tcpmssfix in the ppp program, but since the pptp is using the
> pppd I didn't see any patch to this (or I didn't recognize it).

Did you try turning on or off some IP options ?
Especially turning off PMTU discovery on the clients machine.

Manuel Bouyer, LIP6, Universite Paris VI.