With IPHost Network Monitor you can run simple snmp requests against a Nortel device in your network.
vctVcfrCombErrorsFromSubnet
VC Tester Vcfr Comb Errors From Subnet
1.3.6.1.4.1.562.2.4.1.5130.5.12.1.6
This attribute records the number of subnet packets discarded at the sink Vc due to the Vc segmentation and combination protocol error. Usually, this occurs when the subnet discards packets and thus this statistics can be used to guest the number of subnet packets that are not delivered to the Vc. It cannot be used as an actual measure because some subnet packets may have been delivered to Vc but have to be discarded because these are partial packets to a frame in which some other partial packets have not been properly delivered to Vc
Back to Nortel-Magellan-Passport-VcTesterMIB MIB page.
IPHost Network monitor allows you to monitor vctVcfrCombErrorsFromSubnet 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.