ip route add 172.31.1.0 dev eth0 src 172.31.1.2 table T1
ip route add 192.168.1.0 dev eth3 src 192.168.1.2 table T1
ip route add default via 172.31.1.1 table T1
ip route add 172.31.2.0 dev eth1 src 172.31.2.2 table T2
ip route add 192.168.1.0 dev eth3 src 192.168.1.2 table T2
ip route add default via 172.31.2.1 table T2
ip route add 172.31.3.0 dev eth2 src 172.31.3.2 table T3
ip route add 192.168.1.0 dev eth3 src 192.168.1.2 table T3
ip route add default via 172.31.3.1 table T3
ip route add 172.31.4.0 dev eth2:0 src 172.31.4.2 table T4
ip route add 192.168.1.0 dev eth3 src 192.168.1.2 table T4
ip route add default via 172.31.4.1 table T4
ip route add 172.31.1.0 dev eth0 src 172.31.1.2
ip route add 172.31.2.0 dev eth1 src 172.31.2.2
ip route add 172.31.3.0 dev eth2 src 172.31.3.2
ip route add 172.31.4.0 dev eth2:0 src 172.31.4.2
ip rule add from 172.31.1.2 table T1
ip rule add from 172.31.2.2 table T2
ip rule add from 172.31.3.2 table T3
ip rule add from 172.31.4.2 table T4
ip route add default scope global nexthop via 172.31.1.1 dev eth0 weight 1 nexthop via 172.31.2.1 dev eth1 weight 1 nexthop via 172.31.3.1 dev eth2 weight 1 nexthop via 172.31.4.1 dev eth2:0 weight 1