Select a device implementing RIPv2-MIB 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 rip2PeerLastUpdate under the rip2PeerEntry branch of RIPv2-MIB, selecting the specific row/instance you want to monitor since this is a table column, then select it and click OK. It records sysUpTime at the moment the most recent RIP update was received from this peer — comparing it against the device's current sysUpTime tells you how long it's been since that peer last sent an update. 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 time since the last update from this peer exceeds a few RIP update intervals (e.g. 3x the normal ~30-second interval), which indicates the peer has likely gone silent or down. Click Finish to create the monitor; you can adjust any parameter later.