Hi All,

I'm trying to setup a router which will route traffic between the following networks 10.0.0.0 and 172.16.0.0

The network is setup like this:

laptop ip 172.16.0.2 --lan/switch-- eth1 172.16.0.1 router A eth0 10.0.0.2 ---lan/switch--- eth0 10.0.0.1 router B eth1 inet ip.

I have added the following on router B

route add -net 172.0.0.0 netmask 255.255.255.0 dev eth0
route add -net 172.0.0.0 netmask 255.255.255.0 gw 172.16.0.1

router A

route add -net 10.0.0.0 netmask 255.255.255.0 dev eth0
route add -net 10.0.0.0 netmask 255.255.255.0 gw 10.0.0.20

I can ping router a's ip 10.0.0.1 from a machine behind router a and can ping from router b to 172.16.0.1

Machines on the 10 subnet have 10.0.0.1 set as thier gw.

The problem is I cannot ping any lan machines on the 10 subnet from the laptop 172.16.0.2 sitting behind router A 172.16.0.1 subnet and its the same from the 10.0.0.0 subnet with out adding a static route on each machine.

Any ideas?

core09

I am a little confused by your configuration. You have two routers where I only see the need for one. Is there a third network hiding somwhere? The function of a router is to move traffic from one network (like your 10 network) to another network (like your 172 network). I would expect you to have only one router with one net on eth0 and the other net on eth1.

I would set up your net with a switch/hub connected to each of the interfaces on one router and then approach your routing.

I'm guessing you've got the second router since you've technically got 3 networks (10.x, 172.x and t'internet). However, normsherer is right, you could get away with just one router. It all depends on the physical locations of the machines.

Anyway, back to the problem at hand. Have you enabled ip forwarding on the routers? Also, I assume it's a typo in router A's gateway specification (10.0.0.20?)

If the forwarding isn't the problem, post the result of running 'route -n' on all the machines. Enclose the results in [CODE] tags to make them readable.