Subject: In-kernel pppoe experiences
To: Martin Husemann <>
From: George Coulouris <>
List: current-users
Date: 11/14/2001 21:24:23

Just some experiences with in-kernel pppoe..

After switching from rp-pppoe, I started getting the sendmail errors
described in:

I set

net.inet.ip.mtudisc = 1
net.inet.tcp.mss_ifmtu = 1

, and these seem to have helped things a bit; mail is flowing again without

I believe the same mtu/mss issues may be causing problems with ipnat as
well. If I set the MTU on my iBook (running MacOS 10.1, sitting behind my
NetBSD/i386 NAT box) to 1452, things seem to work more reliably than if it's
set to 1500.

During my experiments, I tried to change the MTU on the pppoe0 interface to
1500 caused my machine to freeze, couldn't break into ddb or anything :(

Should the ethernet interface underlying the pppoe connection (in my case,
rtk0) also have its mtu set to 1452?