With IPHost Network Monitor you can run simple snmp requests against a Cisco device in your network.
rprSpanIntervalInUcastClassAFrames
rpr Span Interval In Ucast Class A Frames
1.0.8802.17.1.1.1.3.2.1.7
The number of received (PHY to MAC) classA unicast frames in a particular interval in the past 24 hours.
Back to IEEE-802DOT17-RPR-MIB MIB page.
IPHost Network monitor allows you to monitor rprSpanIntervalInUcastClassAFrames 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.