With IPHost Network Monitor you can run simple snmp requests against a Nortel device in your network.
timeTimeOffset
time Time Offset
1.3.6.1.4.1.3646.1300.2.1.2.1.10.1.4
The timeOffset attribute is the number of minutes, to add to the reference time, which is equal to the Universal Coordinated Time (UTC), to obtain the moduleTime.
Back to Nortel-Magellan-Passport-TimeMIB MIB page.
IPHost Network monitor allows you to monitor timeTimeOffset 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 multiplexers right now.