With IPHost Network Monitor you can run simple snmp requests against a Cisco device in your network.
cagwIdleModeEntryFailures
Cisco's ASN Gateway Idle Mode Entry Failures
1.3.6.1.4.1.9.9.638.1.3.1.1.1.103
The number of idlemode entry failures.
Back to CISCO-ASN-GATEWAY-MIB MIB page.
IPHost Network monitor allows you to monitor cagwIdleModeEntryFailures on Cisco device via the SNMP protocol. Download IPHost Network Monitor (500 monitors for 30 days, 50 monitors free forever) to start monitoring Cisco firewalls right now.