With IPHost Network Monitor you can run simple snmp requests against a D-Link device in your network.
swL2StpPortEntry
Switch L2 Stp Port Entry
1.3.6.1.4.1.171.11.70.5.2.16.4.1
A list of information maintained by every port about the Spanning Tree Protocol state for that port.
Back to DES3010G-L2MGMT-MIB MIB page.
IPHost Network monitor allows you to monitor swL2StpPortEntry on D-Link device via the SNMP protocol. Download IPHost Network Monitor (500 monitors for 30 days, 50 monitors free forever) to start monitoring D-Link switches right now.