With IPHost Network Monitor you can run simple snmp requests against a Nortel device in your network.
x25DtePLcnInPacketSize
x25 Dte P Logical Channel Number In Packet Size
1.3.6.1.4.1.562.2.4.1.90.3.10.1.5
This attribute specifies the maximum receive packet size in octets.
Back to Nortel-Magellan-Passport-X25DteMIB MIB page.
IPHost Network monitor allows you to monitor x25DtePLcnInPacketSize 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.