Hello people.
I'm an informatic student and i am trying to improve my routing/bridging knowledge.

On my machine i installed xen and created 3 DomU.
After that i created this network with bridges:

....N1(node1).........................N2(node2)
eth0:172.16.0.2 <---br0---> |eth0:172.16.0.1|
....N3(node3)......................|.....................|
eth0:172.16.1.2 <---br1---> |eth1:172.16.1.1|

br0 and br1 are 2 bridges connecting the NIC of N1 and N3 with the two owned by N2.

From the N1 node i can ping the addresses 172.16.0.1 and 172.16.1.1, but the N3 host is unreachables.

I think that the problem could be the routing table of the N2 node, but i can't find a solution to my problem: N1 and N3 cannot comunicate.

I hope i can find some help/advices here, something i could study..dunno...everything will help.

i just solved the problem. I had to enable the ip farwarding on node N2. And thats what i did:

echo 1 > /proc/sys/net/ipv4/ip_forward.

Now i can ping N1 from N3.