With IPHost Network Monitor you can run simple snmp requests against a Cisco device in your network.
cIpAddressPrefix
Cisco Ip Address Prefix
1.3.6.1.4.1.9.10.86.1.1.2.1.5
A pointer to the row in the prefix table to which this address belongs. May be { 0 0 } if there is no such row.
Back to CISCO-IETF-IP-MIB MIB page.
IPHost Network monitor allows you to monitor cIpAddressPrefix on Cisco device via the SNMP protocol. Download IPHost Network Monitor (500 monitors for 30 days, 50 monitors free forever) to start monitoring Cisco firewalls right now.