With IPHost Network Monitor you can run simple snmp requests against a Nortel device in your network.
vrPpFddiETBForwardTransitions
Virtual Router Passport Fddi ETB Forward Transitions
This attribute is indicative of the number of times this bridge port transitioned from the learning state to the forwarding state. This counter wraps around its maximum value of 4294967295. A rapidly increasing value might be indicative of an unstable spanning tree topology.
Back to Nortel-Magellan-Passport-BridgeMIB MIB page.
IPHost Network monitor allows you to monitor vrPpFddiETBForwardTransitions 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 speech servers right now.