With IPHost Network Monitor you can run simple snmp requests against a D-Link device in your network.
ringStationTable
ring Station Table
1.3.6.1.2.1.16.10.2
A list of ring station entries. An entry will exist for each station that is now or has previously been detected as physically present on this ring.
Back to TOKEN-RING-RMON-MIB MIB page.
IPHost Network monitor allows you to monitor ringStationTable 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.