With IPHost Network Monitor you can run simple snmp requests against a Cisco device in your network.
cGgsnSANotifCsgRealAddress
Cisco Ggsn Service-Aware Notification Content Services Gateway Real Address
1.3.6.1.4.1.9.9.497.1.4.2
This object indicates the real IP address of the CSG group.
Back to CISCO-GGSN-SERVICE-AWARE-MIB MIB page.
IPHost Network monitor allows you to monitor cGgsnSANotifCsgRealAddress 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.