My Primus Supplied Dlink DVG-1120M voice gateway keeps restarting. It happens typically when I click on a message on the Exchange server, when I haven’t had any exchange activity in a while. It reboots itself and renders my internet connection useless. So this evening I took on the mission of re-arranging the network so that I don’t have to rely on that Dlink hardware to run the show. Now the FreeBSD box is routing traffic via PPPoE to the DSL modem and there’s a seperate network for the Dlink, hopefully that will allow it to maintain it’s QoS and not drop calls because of slow packets. Only time will tell on that one. Once I got it all set up, I couldn’t get to some sites, and MSN wouldn’t work. It’s always an MTU issue when that happens. After hours of trial and error and Googling to no avail, the trick was to set the mtu on the tun0 to 1452 via ppp.conf. The line has to read

set mtu max 1452
I had set mtu 1452 (and I tried the suggested set mtu 1492 for hours!) and the tun0 interface continued to be at 1492 and still those troublesome sites and MSN Messenger wouldn’t work. If you set the mtu manually using ifconfig, it seems to do nothing to help you. In fact, if you try setting the mtu of the network card that’s plugged into the modem, you’ll break everything. Good to know.


     I had to fix this before I go to bed because I have lots of stuff to do first thing in the morning, and if I didn’t fix this, it would have continued to bother me. I guess it’s like that never go to bed angry thing… never go to bed stuck at your technology. Although, there have been quite a few times where I’ve abandoned a problem in the middle of it and then come back in the morning for a fresh look, but I guess at that point, I was still a slave to it because first thing the next day I was there.

Author: Ian

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