With IPHost Network Monitor you can run simple snmp requests against a Cisco device in your network.
ccpcPcfSentZlbs
CISCO CDMA PDSN CRP Pcf Sent Zlbs
1.3.6.1.4.1.9.9.957.1.2.1.1.14
Total number of Zero-Length-Buffer messages sent since the L2TP tunnel was established with PCF.
Back to CISCO-CDMA-PDSN-CRP-MIB MIB page.
IPHost Network monitor allows you to monitor ccpcPcfSentZlbs on Cisco device via the SNMP protocol. Download IPHost Network Monitor (500 monitors for 30 days, 50 monitors free forever) to start monitoring Cisco routers right now.