How to down particular ip in linux?

Hie folks, I am trying to down particular IP from the set of up IP's, how to do this? For example lets consider I had up following IP's(sequence will be same): 1.2.3.4 1.2.3.5 1.2.3.6 I did this using "ifconfig etho:x 1.2.3.x up" where x=4,5,6. Now I want to down first IP alone i.e. 1.2.3.4, I am trying this as "ifconfig eth0:4 down". Problem is this not only downs required IP but also downs all the IP below it. I am working on Linux RedHat. Thanks in advance...