With IPHost Network Monitor you can run simple snmp requests against a Nortel device in your network.
x25DtePleX25AddrToEncLkupFlrs
x25 Dte Ple X25 Address To Enc Lkup Flrs
1.3.6.1.4.1.562.2.4.1.90.6.11.1.4
This attribute indicates the number of times a translation attempt from an X.25 address to an Encapsulation address failed to find a corresponding Encapsulation address. Such a failure could occur when a incoming call received from the link by the X.25 DTE is directed to a specific RemoteGroup because the called address matches the localAddress attribute of the RemoteGroup component. If the RemoteGroup component does not have a Peer component linked in its linkToPeer attribute list, with the x25Address attribute equal to the calling address from the incoming call packet, there is no appropriate Peer component, so the call is cleared and this counter is incremented.
Back to Nortel-Magellan-Passport-X25DteMIB MIB page.
IPHost Network monitor allows you to monitor x25DtePleX25AddrToEncLkupFlrs 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.