ePDG is the part of SAE which interfaces with non-trusted 3GPP IP systems. It acts as a secure termination node for IPsec tunnels established with UE.
What are un-trusted non-3GPP accesses?
When a network operator doubts on the secured interface of a technology its categorized as un-trusted. The very good example is of WiFi hotspot.
Multiple cores from different networks can be integrated in a single LTE node. Enhanced back haul security through IPSec tunnels. Rapid packet processing. Real time subscribers, service and applications monitoring for in-line services.