With IPHost Network Monitor you can run simple snmp requests against a Nortel device in your network.
shelfCardMemoryUsageAvgTable
shelf Card Memory Usage Average Table
1.3.6.1.4.1.43.1.12.3.1.1.2.2.276
This attribute indicates the processor's average memory utilization (in kilobytes) for each type of memory in the specified time period, timeInterval. This value is calculated using 15 second samples.
Back to Nortel-Magellan-Passport-ShelfMIB MIB page.
IPHost Network monitor allows you to monitor shelfCardMemoryUsageAvgTable 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 secure routers right now.