With IPHost Network Monitor you can run simple snmp requests against a Cisco device in your network.
alL2tpStatsTunnelControlOutOfWindow
ALTIGA L2tp Statistics Tunnel Control Out Of Window
1.3.6.1.4.1.3076.2.1.2.16.2.1.18
This object contains the number of control packets that were received outside of the offered receive window. It is implementation specific as to whether these packets are queued or discarded.
Back to ALTIGA-L2TP-STATS-MIB MIB page.
IPHost Network monitor allows you to monitor alL2tpStatsTunnelControlOutOfWindow 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.