Uses the MIT SNMP toolkit and TCL/TK. All kinds of nice functionality.
Implement security, Standard MIBs, Customized MIB views, protect denial of service and make it able to handle a hetergenous environment.
Auto-discovery of topology, connection tables, trace connections (point-to-point and point-to multipoint), etc.
RFC 1695 illustrated some of the concepts used for auto-discovery.
PVC Traceroute is able to use the SNMP proxy agent to determine the path through a switch for a particular connection.