How do I implement stateful NAT (SNAT)?
A. SNAT enables continuous service for dynamically mapped NAT sessions. Sessions that are statically defined receive the benefit of redundancy without the need for SNAT. In the absence of SNAT, sessions that use dynamic NAT mappings would be severed in the event of a critical failure and would have to be reestablished. Only the minimal SNAT configuration is supported. Future deployments should be performed only after talking to your Cisco Account Team in order to validate the design relative to current restrictions. For more information about implementing SNAT, refer to Configuring NAT for High Availability. SNAT is recommended for the following scenarios: • HSRP mode as described in the SNAT white-paper: Enhanced IP Resiliency Using Cisco Stateful NAT. • Primary/backup is not a recommended mode since there are some features missing compared to HSRP. • For fail-over scenarios and for 2-router setup. That is, if one router crashes, the other router takes over seamlessly. (SNAT architect
