Network Spy Site License - description from Softdepia.com:
An ethernet packet capture program. It allows to you decode and analyze IP packets on your LAN. It also lets you measure network load, resolve IP conflicts and build an ARP table. New features include remote capture and filter-by-IP. This program is lightweight and displays captured frames in realtime - ideal for network programmers, administrators and people learning the TCP/IP suite of protocols.
Network Spy Site License is a "Free to try" program. You can download and try it for an evaluation period.