Need some opinions on making a multihomed box more resilient to failure. This server runs asterisk and performs nat and firewalling for an office. Its wan nic is plugged directly into a cable modem and I am stuck with it being configured as a dhcp client. The lan nic services a small office, and has a static IP but of course, no default gateway.
When an internet outage occurs, asterisks sip stack tanks and the pbx dives. So I have setup fqdn's/ip's in the hosts file for all sip peers it will attempt to resolve, and setup a local dns with all rfc1912 zones so every query asterisk can possibly make will be answered locally.
Now it seems there is still one last hurdle, when the connection is yanked to simulate a complete outage, asterisk still goes down. I can only assume this happens now as a result of no default gateway?
Would setting up a silly route for 0.0.0.0/0 to say 127.0.0.1 for the internal nic in /etc/sysconfig/network-scripts/route-eth1 with a metric higher than what the ISP's dhcp servers default gw would be possibly cure this? My hope is that when the wan nic goes down, a route is still available.
I can't think of any other network shortcoming that is left when that external nic goes down, I am hoping this is finally it, so asterisk will stop core dumping and yelling "Serious Network Trouble".
Thanks! jlc