With IPHost Network Monitor you can run simple snmp requests against a Cisco device in your network.
cgkZoneSubnetTable
Cisco Gatekeeper Zone Subnet Table
1.3.6.1.4.1.9.10.40.1.1.2
The table identifies communication characteristics between a gatekeeper and endpoints whose RAS address is on specified IP subnets. This table is appropriate for a zone whose znRasAddressTag is 'ipv4' or 'ipv6'.
Back to CISCO-GATEKEEPER-MIB MIB page.
IPHost Network monitor allows you to monitor cgkZoneSubnetTable on Cisco device via the SNMP protocol. Download IPHost Network Monitor (500 monitors for 30 days, 50 monitors free forever) to start monitoring Cisco switches right now.