If you need a live monitoring of the inbound and outbound traffic rate across a network interface you can try speedometer. I found this command-line based tool very user-friendly.
sudo apt-get install speedometer
-tx options to display bytes received and transmitted on network interface. For example, if your network interface card name is
eth0 use the following command:
speedometer -rx eth0 -tx eth0
A live graph like the one shown blow will be displayed in the terminal window. By default, the graph is updated every second. You can change update intervals if you wish.
For more information read the man pages using
man speedometer after installing.