route: SIOCADDRT: Network is unreachable

this is a bare bone embedded system,
don't think we have those if-up, if-down etc.

have eth0 and eth1,both static ip.
eth0 is not plugged in initially.


# route -n
Kernel IP routing table
Destination Gateway Genmask Flags Metric Ref Use
Iface
0.0.0.0 10.50.183.254 0.0.0.0 UG 0 0 0 eth1
10.50.180.0 0.0.0.0 255.255.252.0 U 0 0 0 eth1


then i plugin eth0, assign ip through ifconfig.

#route add default gw 10.50.183.254 eth0
#route: SIOCADDRT: Network is unreachable

how should i add the route correctly ?

thanks !