With IPHost Network Monitor you can run simple snmp requests against a D-Link device in your network.
swL2PTProtocolIndex
Switch L2 PT Protocol Index
1.3.6.1.4.1.171.12.93.1.3.1.1
This object indicates the tunneled protocol of the port.
Back to L2PROTOCOL-TUNNEL-MIB MIB page.
IPHost Network monitor allows you to monitor swL2PTProtocolIndex 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 routers right now.