With IPHost Network Monitor you can run simple snmp requests against a Cisco device in your network.
cnatAddrBindSessionCount
cnat Address Bind Session Count
1.3.6.1.4.1.9.10.77.1.2.2.1.7
Number of sessions currently using this BIND.
Back to CISCO-IETF-NAT-MIB MIB page.
IPHost Network monitor allows you to monitor cnatAddrBindSessionCount on Cisco device via the SNMP protocol. Download IPHost Network Monitor (500 monitors for 30 days, 50 monitors free forever) to start monitoring Cisco multiplexers right now.
