Archive for August, 2008

trixbox Pro, DNS, and internet outages – what I have learned from my pain

August 29, 2008 Leave a comment

With the floods here in Iowa this summer I suddenly had several customers with no internet connections. I expected voip trunks to not work, but several of them also were losing registration on all their phones. I thought I had understood how to set up DNS properly, but I did not quite have it.

Here’s the best formula as I understand it:

Have your gateway use a valid public DNS server.
Have the trixbox Pro server use the gateway as the primary DNS, and a public DNS server as the secondary DNS
Have the phones use the trixbox Pro server as their only DNS.

One thing that drove me about insane was my sandbox server was on a cheap netgear router. I guess cheap routers can’t be counted on to function properly at all without a WAN link. I could unplug the WAN link and within a minute the phones would lose registration, even with everything else set up correctly. Today I put an IPCOP firewall on the sandbox network and everything functions exactly like it should without the WAN link.

A Linksys WRT54G loses registrations at intervals but keeps the trixbox Pro system marginally functional. A Linksys WRTT54G with DD-WRT firmware functions properly, though.

A related problem with VERY similar symptoms:
Having a SIP trunk with a FQDN will cause all phones to unregister in the event of an internet outage. Changing to a straight IP address removes that problem. I guess that is an asterisk bug.