With IPHost Network Monitor you can run simple snmp requests against a D-Link device in your network.
swL2TrunkMember
Switch L2 Trunk Member
1.3.6.1.4.1.171.11.70.5.2.9.3.1.4
Indicates the number of ports included in this Trunk group. The trunk port number depends on the existence of the module. The maximum number of ports is 8 for one trunk group.
Back to DES3552-L2MGMT-MIB MIB page.
IPHost Network monitor allows you to monitor swL2TrunkMember 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 VPN routers right now.