With IPHost Network Monitor you can run simple snmp requests against a Cisco device in your network.
cnatAddrBindNumberOfEntries
cnat Address Bind Number Of Entries
1.3.6.1.4.1.9.10.77.1.2.1
This object maintains a count of the number of entries that currently exist in the cnatAddrBindTable.
Back to CISCO-IETF-NAT-MIB MIB page.
IPHost Network monitor allows you to monitor cnatAddrBindNumberOfEntries 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.