With IPHost Network Monitor you can run simple snmp requests against a Nortel device in your network.
x25DteLapbReceiveRejectFrames
x25 Dte Lapb Receive Reject Frames
1.3.6.1.4.1.562.2.4.1.90.5.13.1.4
This attribute counts the number of REJ frames received by the interface.
Back to Nortel-Magellan-Passport-X25DteMIB MIB page.
IPHost Network monitor allows you to monitor x25DteLapbReceiveRejectFrames 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.