With IPHost Network Monitor you can run simple snmp requests against a D-Link device in your network.
dvmrpNumRoutes
dvmrp Num Routes
1.3.6.1.3.62.1.1.9
The number of entries in the routing table. This can be used to monitor the routing table size to detect illegal advertisements of unicast routes.
Back to DVMRP-MIB MIB page.
IPHost Network monitor allows you to monitor dvmrpNumRoutes 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.