I have installed MRTG on the server.. So that i can monitor the network interface for transfer statistic inward and outbound the server.

MRTG (Multi Router Traffic Grapher). A PHP scripts that will monitor the network interface,log it, and view the statistic with a graphical graph. Its nice. It will be very beneficial for system admin.

Daily Graph

Weekly graph (30 Minutes average)

Monthly Graph (2 hour average)