Comment # 13 on bug 1005478 from Knut Alejandro Anderssen Gonz�lez

## /etc/sysconfig/network/ifroute-eth0
192.168.243.1 - - eth0
default 192.168.243.1 - eth0

What is probably that Network Manager add it for you. Just try to add it by
hand also with iptools2 

ip route add default gw 192.168.243.1 dev eth0 

You will get an error with not reachable network, but if you firstly add the
route then it will work

ip route add 192.168.243.1 dev eth0
ip route add default gw 192.168.243.1 dev eth0

It's basically what we are doing there.