Deleting Duplicated default gateways on AIX

Ever had that weird problem on AIX where your routing table has a second default gateway?

I had and this is how i fixed it. In my case when I changed a ip address and default gateway in smitty, the routing table ended up with TWO default gateways. This is bad news if your machine is a seperate vLAN or subnet and needs to communicate outside of this vLAN or subnet.

The example below shows the output of a netstat -rn. In it you can see two default gateways. One is correct 10.2.98.113 and the other 10.0.72.16 is incorrect.

However the incorrect one is not listed in aix smitty nor is it in /etc/rc.net /etc/defaultgateways.

To get rid of the rogue gateway and restore connectivity I listed the device attributes for the interface. To do this type from the aix machine console I typed:

lsattr -E -l inet0

which gave the following output

I then typed the chdev command again from the aix console. NOTE: Caution when doing this if connected over a network interface from another host as you are altering the network!!

chdev -l inet0 -a delroute=net,-hopcount,0,,0,10.0.72.1

if you look at closely this chdev command you can see basically the part after the delroute attribute was copied exactly from the above lattrb command output. This is what you will need to do for your environment.

After this was completed the second default route was removed and connectivity was restored.