What kind of routing performance can be expected when using Cisco IOS NAT?

Cisco IOS NAT supports Cisco Express Forwarding switching, fast switching, and process switching. For 12.4T release and later, fast-switching path is no longer supported. For Cat6k platform, the switching order is Netflow (HW switching path), CEF, process path.

Performance depends on several factors:

• The type of application and its type of traffic
• Whether IP addresses are embedded
• Exchange and inspection of multiple messages
• Source port required
• The number of translations
• Other applications running at the time
• The type of hardware and processor