Hi,

I have a following network scenario with Ubuntu 10.04 Server.


PC ---Router-1 -----Router-2 ======== Server (eth0 and eth1)


I need to ping the server's both NIC from PC. However only 1 NIC replies. How can I make both NIC reply? Traffic entering each NIC should leave the same NIC that the traffic came through.
Here is my interface config:

auto lo
iface lo inet loopback

auto eth0
iface eth0 inet static
address 10.29.172.38
netmask 255.255.255.252
network 10.29.172.36
broadcast 10.29.172.39
gateway 10.29.172.37

auto eth1
iface eth1 inet static
address 10.29.170.146
netmask 255.255.255.252
network 10.29.170.144
broadcast 10.29.170.147
gateway 10.29.170.145

Any help will be appreciated.

You have 2 gateways,
Are those the 2 interfaces in router2 facing the server?

You can traceroute from PC to the server to check where the connection breaks. I am thinking that, since you have setup 2 different networks, you need to be able to route to those 2 separate networks; and currently you are only able to route to only 1 of them.

Yes and they are on two different subnets.

Traceroute to Server's both NIC goes upto router2, however only 1 nic replies. Here is the route -n from the server:

xxxxxxx@SERVER:~# route -n
Kernel IP routing table
Destination Gateway Genmask Flags Metric Ref Use Iface
0.0.0.0 10.29.170.145 0.0.0.0 UG 100 0 0 eth1
0.0.0.0 10.29.172.37 0.0.0.0 UG 100 0 0 eth0
10.29.170.144 0.0.0.0 255.255.255.252 U 0 0 0 eth1
10.29.172.36 0.0.0.0 255.255.255.252 U 0 0 0 eth0

Sorry I'm not that familiar with routing in Linux yet. But, you've isolated the problem since the connection gets broken when it reaches router2. Can you ping the NIC which doesn't reply from router2? (if it has that capability)

What I'm trying to say is that, you have to setup routing on the router so it would know how to forward traffic to both 10.29.172.36 and 10.29.170.144 networks.