With IPHost Network Monitor you can run simple snmp requests against a Cisco device in your network.
cssgPortMapSourceIp
cssg Port Map Source Ip
1.3.6.1.4.1.9.9.260.1.9.2.1.2
Specifies SSG source IP addresses to be used while NATting packets from downstream traffic i.e., traffic from Subscriber to SSG.
Back to CISCO-SSG-MIB MIB page.
IPHost Network monitor allows you to monitor cssgPortMapSourceIp on Cisco device via the SNMP protocol. Download IPHost Network Monitor (500 monitors for 30 days, 50 monitors free forever) to start monitoring Cisco switches right now.