CCIE Practical Studies: Security (CCIE Self-Study)

Network Address Translation Overview

Network Address Translation (NAT), as described in RFC 1631, “The IP Network Address Translator (NAT),” was developed to address two key shortcomings facing the Internet: the depletion of IP address space and scaling in routing. By using NAT, your IP network appears to the outside as if it is coming from a different IP address space. This means that you are allowed to use the private IP address ranges reserved in RFC 1918, “Address Allocation for Private Internets,” on your network without having to worry about them not being routable in a public space. NAT takes your private addresses and translates them into a routable IP address range, which is normally supplied by your ISP. One other benefit of NAT is ...