Select a router or gateway running Data Link Switching (DLSw) as the target host to create a monitor — the SNMP service should be up and running on it. Click New Monitor, then check SNMP Custom on the Favorites tab, click Next, and confirm the host. On the next page, click Select... to open the built-in SNMP MIB Browser and type dlswNodeUpTime into the Find box to locate it in the OID tree, then select it and click OK. It reports, in hundredths of a second, how long the DLSw (Data Link Switching) subsystem has been running since it was last (re)initialized. On the monitor's Main parameters page you can set the target's SNMP port (default 161), credentials, polling interval, and other settings — see the SNMP Monitor help for details. On the State conditions and Alerting tabs, configure when the monitor should change state and trigger an alert; since this is a TimeTicks-type OID, Value bounds is the most useful condition here — trigger an alert if the uptime resets to a small value unexpectedly, which indicates the DLSw subsystem restarted. Click Finish to create the monitor; you can adjust any parameter later.