With IPHost Network Monitor you can run simple snmp requests against a Cisco device in your network.
cvTotalEncapsFailedDrops
Cisco Voice Total Encaps Failed Drops
1.3.6.1.4.1.9.9.17.1.3.15
Total count of number of VINES packets dropped due to output encapsulation failed.
Back to CISCO-VINES-MIB MIB page.
IPHost Network monitor allows you to monitor cvTotalEncapsFailedDrops 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.