With IPHost Network Monitor you can run simple snmp requests against a Nortel device in your network.
trkMaxTxUnit
trk Max Tx Unit
This is the maximum transmission unit (byte size) that is supported by the Trunk or DpnGateway component. This size includes the data and routing headers. A value of zero indicates the MTU has not yet been determined.
Back to Nortel-Magellan-Passport-TrunksMIB MIB page.
IPHost Network monitor allows you to monitor trkMaxTxUnit 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.