With IPHost Network Monitor you can run simple snmp requests against a Cisco device in your network.
cefPrefixAddr
CISCO Express Forwarding Prefix Address
1.3.6.1.4.1.9.9.492.1.1.2.1.2
The Network Prefix Address. The type of this address is determined by the value of the cefPrefixType object. This object is a Prefix Address containing the prefix with length specified by cefPrefixLen. Any bits beyond the length specified by cefPrefixLen are zeroed.
Back to CISCO-CEF-MIB MIB page.
IPHost Network monitor allows you to monitor cefPrefixAddr 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.