With IPHost Network Monitor you can run simple snmp requests against a Nortel device in your network.
vrBrTbStpTimeSinceTopologyChange
Virtual Router Br Tb Stp Time Since Topology Change
This attribute specifies the time since a spanning tree topology change was detected by this bridge.
Back to Nortel-Magellan-Passport-BridgeMIB MIB page.
IPHost Network monitor allows you to monitor vrBrTbStpTimeSinceTopologyChange on Allied Telesis device via the SNMP protocol. Download IPHost Network Monitor (500 monitors for 30 days, 50 monitors free forever) to start monitoring Nortel switches right now.