Two IPs on one NIC ( network card )

I have a dedicated server with one network card in it. I however got two IP adresses. When I use the simple command sudo ip addr add 188.40.90.88 dev eth0 it fails to see it as a seperate IP. I've googled along trying to find a fix, but I can't really find out what packages I need to set up a switch, and how to do it.

My dedicated server runs with the following specifications: 16GB DDR3 RAM ( intel i7 ) OS: ubuntu 14.01

These are the two most important ones, I believe, I've got no idea what network card my dedicated server has, but I know it supports IEEE 802.1q, which I found out on the ubuntu website.