With IPHost Network Monitor you can run simple snmp requests against a Cisco device in your network.
stpxRootGuardConfigPortIndex
stpx Root Guard Config Port Index
1.3.6.1.4.1.9.9.82.1.5.1.1.1
The value of dot1dBasePort (i.e. dot1dBridge.1.4) for the bridge port.
Back to CISCO-STP-EXTENSIONS-MIB MIB page.
IPHost Network monitor allows you to monitor stpxRootGuardConfigPortIndex on Cisco device via the SNMP protocol. Download IPHost Network Monitor (500 monitors for 30 days, 50 monitors free forever) to start monitoring Cisco routers right now.