With IPHost Network Monitor you can run simple snmp requests against a Cisco device in your network.
rprSpanCountersCurrentEntry
rpr Span Counters Current Entry
1.0.8802.17.1.1.1.3.1.1
Frames and octets statistics for the current interval for the RPR MAC Span interface. The corresponding instance of rprIfStatsControlTimeElapsed indicates the number of seconds which have elapsed so far in the current interval.
Back to IEEE-802DOT17-RPR-MIB MIB page.
IPHost Network monitor allows you to monitor rprSpanCountersCurrentEntry 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.