As part of this functionality, you can
con?¬?gure NAT to advertise only one address for the entire network to the outside world.
Advertising only one address effectively hides the internal network from the world, thus
providing additional security. Figure 7-1 shows an example of address translation between
a private and public network.
Figure 7-1 Network Address Translation
Inside Global
IPv4 Address
Inside Local
IPv4 Address
171.69.58.80
171.69.58.81
10.0.0.1
10.0.0.2
NAT Table
10.0.0.2
10.0.0.1
SA
10.0.0.1
Inside Outside
Internet
SA
171.69.58.80
Scaling the Network with NAT and PAT 251
Any device that is between an internal network and the public network??”such as a ?¬?rewall,
a router, or a computer??”uses NAT, which is de?¬?ned in RFC 1631.
In NAT terminology, the inside network is the set of networks that are subject to translation.
The outside network refers to all other addresses. Usually these are valid addresses
located on the Internet.
Cisco de?¬?nes the following list of NAT terms:
?– Inside local address: The IPv4 address that is assigned to a host on the inside network.
The inside local address is likely not an IPv4 address assigned by the Network
Information Center or service provider.
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