[asterisk-users] Networking Question

I have an Asterisk server running REL 4 with two NICs. One NIC has a 192.168.1.x IP address and is connected to a POE switch with Polycom phones that have 192.168.1.x IP addresses.

 

The other NIC has a 172.17.x.x IP address connected to a router.  The router is connected to the Internet.

 

If the Internet goes down or the cable between the 172.17.x.x. NIC is disconnected, the phones start to lose their connection to asterisk. Why?  What have I screwed up?

 

Thanks,
Brian