How do I implement NAT in conjucntion with IPSec?
A. There is support for IP Security (IPSec) Encapsulating Security Payload (ESP) through NAT and IPSec NAT Transparency. The IPSec ESP through NAT feature provides the ability to support multiple concurrent IPSec ESP tunnels or connections through a Cisco IOS NAT device configured in overload or Port Address Translation (PAT) mode. For more information about this feature, refer to Support for IPSec ESP Through NAT and NAT Support for IPSec ESP – Phase II. The IPSec NAT transparency feature introduces support for IPSec traffic to travel through NAT or PAT points in the network by addressing many known incompatabilites between NAT and IPSec. For more information about this feature, refer to IPSec NAT Transparency.
