CentOS 5 Networking :: Ping -I On 5.2 Versus 4.7

I have two CentOS servers on the same LAN. One is CentOS 4.7 the other 5.2 They both also have a WAN interface to the same remote network. On CentOS 4.7 I can ping the remote network through the CentOS 5.2 server. i.e. ping -I eth0 remotehost On CentOS 5.2 I can NOT force the ping to go out the CentOS 4.7 server without over riding my routing tables to make eth0 a more direct route than the eth1 route.

On 5.2 If I do the ping -I eth0 remotehost, and a tcpdump on eth0, the outbound ping will not be going out eth0, he overrides it and sends it out eth1. In fact, on CentOS 4.7 if I do not have a route to the remote network through the other server (turn proxy arp off on the 5.2 machine), I will get "Destination Host Unreachable". I would ideally like to get the 5.2 machine to behave the way the 4.7 machine does.

My real life application for this is that I have a CentOS server in a location that controls access to the Internet. There is another router on the netowrk that handles traffic back to our corporate office. the CentOS server also has the ability to get to the corporate office. I ping the corporate office through eth0 to find out if the link through the other router is indeed up and active. I want to make this a CentOS 5.2 server but alas, I can not tell if the other route is up or not.