Subject: Re: ADSL upstream problems on Sparc NetBSD 1.5
To: None <>
From: Sebastian Wain <>
List: tech-net
Date: 09/07/2001 19:40:54
On Fri, 7 Sep 2001 18:43:01 +0200
Manuel Bouyer <> wrote:

> 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.

I played with net.ipv4.ip_no_pmtu_disc, net.inet.ip.mtudisc, 
net.inet.tcp_mss_ifmtu on the machine connected to the adsl modem.

I didn't especify the problem in my previous mail: 

- Sometimes I loose the connection.

- When I didn't loose the connection, while the machine is
uploading info, the PING to a site with average 85 ms of delay goes to
1000 ms of delay.

Thank You
Sebastian Wain