With IPHost Network Monitor you can run simple snmp requests against a Cisco device in your network.
cagwCreatedSessions
Cisco's ASN Gateway Created Sessions
1.3.6.1.4.1.9.9.638.1.3.1.1.1.3
The total number of sessions created on this ASN-GW which include active and past sessions.
Back to CISCO-ASN-GATEWAY-MIB MIB page.
IPHost Network monitor allows you to monitor cagwCreatedSessions 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.