Select an Avici backbone/core router 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 locate aviciSysInventoryTableChange under the aviciSystemGroup branch of AVICI-SYSTEM-MIB, then select it and click OK. It reports, in TimeTicks (hundredths of a second since the system last rebooted), when the hardware inventory table was last changed — for example, when a module was added or removed. 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 this value changes unexpectedly (e.g. outside a planned maintenance window), since that flags an unplanned hardware inventory change. Click Finish to create the monitor; you can adjust any parameter later.