I assume your on Windows? From memory...
If you got to your LAN settings, select the device e.g 3com ethernet card... and double click on Icon. In the properties window on the bottom left corner there is an option to display icon on task bar - check this.
When connected, move your mouse over the new little PC icon in the task bar - it will show bytes Tx and Rx.
If you know what port the application is on, you could try 'netstat' from the cmd line. read here http://www.unet.univie.ac.at/aix/cmds/aixcmds4/netstat.htm