With IPHost Network Monitor you can run simple snmp requests against a Nortel device in your network.
vctVcfrMaxSubnetPktSize
VC Tester Vcfr Max Subnet Packet Size
1.3.6.1.4.1.562.2.4.1.5130.5.10.1.27
This attribute indicates the maximum packet size allowed on the Vc.
Back to Nortel-Magellan-Passport-VcTesterMIB MIB page.
IPHost Network monitor allows you to monitor vctVcfrMaxSubnetPktSize 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 modems right now.