Monitoring ASA packet loss via SNMP
Solution 1:
Google for "cacti cisco ASA template". That will tell you which OIDs you need.
Mind you that the SNMP indexes for VPN interfaces don't exist unless the tunnel is up!
Solution 2:
Object cufwAspFlowDropsTable OID 1.3.6.1.4.1.9.9.491.1.5.3.4 Description This table lists all the ASP flow drops on this firewall device. https://snmp.cloudapps.cisco.com/Support/SNMP/do/BrowseOID.do?local=en&translate=Translate&objectInput=1.3.6.1.4.1.9.9.491.1.5.3.4#oidContent
CLI equivalent: show asp drop