If you specify two default gateways, the one that happens to be listed first in the routing table will get all the traffic that has no more specific route. The second gateway will be used only if the first one fails.
If you have two independent routes to the Internet and want to load-balance your outgoing traffic between them, you should read the Advanced-Routing-HOWTO (find it in the HOWTO document collection packages for your distribution, or just google for it).
> route add -net 150.150.200.0 netmask 255.255.255.0 gw 150.150.200.1 dev eth1
By your configuration, the eth1 NIC is already directly connected to the 150.150.200.* network and can communicate directly with any host in it. There should be no need to go through the gateway: it only generates unnecessary traffic to the gateway. This route makes no sense.
> route add -net 150.150.220.0 netmask 255.255.255.0 gw 150.150.220.1 dev eth0
The same argument seems to apply to the eth0 NIC too. There should be no need to use any gateway to access any host in the 150.150.220.* network, because eth0 is directly connected to that network.
If you _need_ to specify the routes listed above to make things work, your network may have other problems you should fix instead of working around them. Maybe an incorrect netmask or something?
> from a other network which is connected froma backbone 150.150.218.0/24
i can ping 150.150.220.38 but i cant ping 150.150.200.31
Have you told _the gateway_ that brings in the traffic from the backbone to 150.150.218.* that 150.150.200.31 can be found by going through 150.150.220.38? If you haven't the gateway has no reason to send the traffic in that way and the traffic will never reach your blade.
In other words, the gateway 150.150.220.1 should be configured with a route like this:
route add -host 150.150.200.31 gw 150.150.220.38 dev
And the gateway 150.150.200.1 should be configured with this:
route add -host 150.150.220.38 gw 150.150.200.31 dev
If you want your bl465 to act as a router between the two networks, you should enable IP forwarding and instead of the two routes listed above, you should configure your gateways with routes that allow the entire opposite segment to be reached through your blade:
Route for 150.150.220.1:
route add -net 150.150.200.0 netmask 255.255.255.0 gw 150.150.220.38 dev
Route for 150.150.200.1:
route add -net 150.150.220.0 netmask 255.255.255.0 gw 150.150.200.31 dev
NOTE: before allowing traffic to pass through your blade from one network segment to the other, talk with your network admins.
If you join together two segments that are designed to be separate for e.g. security reasons, the network admins will be very unhappy with you.
The same will be true if you accidentally create a routing loop that brings the network to its knees.
MK
MK
