With IPHost Network Monitor you can run simple snmp requests against a Cisco device in your network.
ceipSecTunInDropPkts
Cisco Enhanced IP Sec Tunnel In Dropped Packets
1.3.6.1.4.1.9.9.432.1.1.2.1.35
The total number of packets dropped during receive processing by this IPsec Phase-2 Tunnel. This count does NOT include packets dropped due to Anti-Replay processing.
Back to CISCO-ENHANCED-IPSEC-FLOW-MIB MIB page.
IPHost Network monitor allows you to monitor ceipSecTunInDropPkts 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.