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21
Overview
Port Address
Translation (PAT)
Configuring Port
Address Translation
(PAT)
A
T
DDRESS
This section describes the Address Translation related commands accessible from
the CLI. Public IP addresses are registered and can be used within a public network
(such as the Internet). Due to the limitation of IP version 4 address space and the
growth of the Internet, public addresses are becoming more scarce. One solution
to this problem is to use private addresses on small LANs and to use Address
Translation when accessing devices on the public network. Address Translation
changes a private address to a public address at the gateway of a public network.
There are two types of address translation:
Port Address Translation (PAT)
Network Address Translation (NAT)
Port Address Translation (PAT) is the most commonly used type of Address
Translation. It maps many private addresses on the local LAN to one public
address. The public address is the WAN interface address, which can be
dynamically learned or statically configured.
Most applications work well when PAT is enabled as long as the connections are
initiated from the client on the local LAN. These applications include:
Web browsing
File Transfer Protocol (FTP) transfers
NetMeeting
Point To Point Tunneling (PPTP)
Typically, PAT only needs to be enabled or disabled for a remote site connection.
Static port configurations map a public port to a private IP address/port. Both TCP
and UDP static ports can be defined. Remote sites can have multiple static ports
defined. If static ports and the Default Workstation are defined, the static ports
take precedence.
RANSLATION
C
OMMANDS
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