21 A DDRESS TRANSLATION C OMMANDSOverview This section describes the Address Translation related commands accessible fromthe 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 thegrowth of the Internet, public addresses are becoming more scarce. One solutionto this problem is to use private addresses on small LANs and to use AddressTranslation when accessing devices on the public network. Address Translationchanges 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 AddressTranslation (PAT)Port Address Translation (PAT) is the most commonly used type of AddressTranslation. It maps many private addresses on the local LAN to one publicaddress. The public address is the WAN interface address, which can bedynamically learned or statically configured.Most applications work well when PAT is enabled as long as the connections areinitiated from the client on the local LAN. These applications include: Web browsing File Transfer Protocol (FTP) transfers NetMeeting Point To Point Tunneling (PPTP)Configuring PortAddress Translation(PAT)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 TCPand UDP static ports can be defined. Remote sites can have multiple static portsdefined. If static ports and the Default Workstation are defined, the static portstake precedence.
