I have a subnet 192.168.1.0/24 that has a PIX515 as the default gateway at 192.168.1.1. All clients on the LAN use the PIX as their default gateway. Recently I added a router with IP 192.168.1.2 that has a second subnet 192.168.2.0/24 connected to it. This being a simple LAN with no routing protocols configured I added the following statement to the PIX:
"route inside 192.168.2.0 255.255.255.0 192.168.1.2"
For some reason this doesn't work for me. To test I added the route statement directly to the clients (Windows) with:
"route add 192.168.2.0 mask 255.255.255.0 192.168.1.2"
and this does work. So apparently the PIX is not redirecting traffic to the 192.168.1.2 router correctly.
How do I fix this?
As Jon already explained, pix doesn't route back traffic on same interface it receives, unless it is code 7
So one option is to upgrade the pix.
Another option is to make the router 192.168.1.2 default-gateway for 192.168.1.0 users.
In the router also configure "ip route 0.0.0.0 0.0.0.0 192.168.1.1"
This way a client, talking to internet, sends first packet to defaultgateway(192.168.1.2), the router receives the packet sends it out to pix and also sends an icmp redirect to the client, informing that the client should use the 192.168.1.1 instead.
A client talking to 192.168.2.0 net, is sending the packet to default-gateway(192.168.1.2), wich is the router connecting the two networks.