What if I have a laptop with Linux and I use it on several locations with several different networks. I have to manually change my network settings every time I change location. What are my options? Is there any tool to aid me on this? Maybe something on which I can configure the three or four settings for my locations and an icon in the notification area to quickly switch between settings?

Sorry, I read that post, but I still do not understand what should I do. Is there any software I need to install first?

Thanks anyway

No you are not supposed to install any software for this. At first you got make 4 copies of your /etc/sysconfig/network-scripts/ifcfg-eth0 with the names you want them to refer as ;

e.g.
cp ../ifcfg-eth0 ../ifcfg-texas
cp ../ifcfg-eth0 ../ifcfg-havana
cp ../ifcfg-eth0 ../ifcfg-delhi

& then edit these three files with different specifications you want. Please also make sure that you should not have ONBOOT=yes in these three secondary addresses.

Now you are done !

Suppose you have now moved to delhi location; So you can do
or now you have moved to texas;
Lets hope that you'll make it working now.