With IPHost Network Monitor you can run simple snmp requests against a Cisco device in your network.
cpimExtRPSetGroupMask
cpim Ext RP Set Group Mask
1.3.6.1.4.1.9.10.120.1.1.7.1.4
The multicast group address mask which, when combined with cpimExtRPSetGroupAddress, gives the group prefix for which this entry contains information about the RP.
Back to CISCO-IETF-PIM-EXT-MIB MIB page.
IPHost Network monitor allows you to monitor cpimExtRPSetGroupMask on Cisco device via the SNMP protocol. Download IPHost Network Monitor (500 monitors for 30 days, 50 monitors free forever) to start monitoring Cisco wireless switches right now.
