With IPHost Network Monitor you can run simple snmp requests against a Cisco device in your network.
rprSpanIntervalOutMcastClassCFrames
rpr Span Interval Out Mcast Class C Frames
1.0.8802.17.1.1.1.3.2.1.37
The number of transmitted (MAC to PHY) classC multicast and broadcast 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 rprSpanIntervalOutMcastClassCFrames 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.