In windows there is a registry entry called Reserve bandwidth. With that system was reserved some bandwidth from my INTERNET connection so that when i am downloading all other connected application can run with minimum INTERNET support. Like reserve bandwidth help to keep other application (all kind of messenger) on-line when i was downloading. But in Ubuntu my connection speed is good enough but problem arise when i am downloading a file, all my messenger gets off-line status. Can any one tell how can i fix such problem? Or why this is happening?