Tracemac is a command-line C++ application that traces a MAC address through the bridging tables of Cisco switches. Unlike some other programs, it uses SNMP. It is not necessary to configure it with network structure information, and no switch passwords need be divulged.

Download: http://www.thtech.net/downloads/tracemac/tracemac-0.02.tar.gz

Freshmeat: http://freshmeat.net/projects/tracemac