With IPHost Network Monitor you can run simple snmp requests against a Cisco device in your network.
stpxPreferredMSTInstancesGroup
stpx Preferred MST Instances Group
1.3.6.1.4.1.9.9.82.3.2.21
An optional group with a collection of objects to support Preferred MST Instance Map feature for Multiple Spanning Tree Protocol on the device.
Back to CISCO-STP-EXTENSIONS-MIB MIB page.
IPHost Network monitor allows you to monitor stpxPreferredMSTInstancesGroup on Cisco device via the SNMP protocol. Download IPHost Network Monitor (500 monitors for 30 days, 50 monitors free forever) to start monitoring Cisco wireless switches right now.