Paradyne 1740 SHDSL manual Nat

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1740 SHDSL 2/4-Wire Router User’s Guide

CHAPTER 8 NAT

Network Address Translation (NAT or NAPT) is a transparent routing function that translates a private IP address on a LAN into a public address that can be used in a public network. Port Address Translation (PAT) is a form of NAT that maps multiple private IP addresses to a single public IP address. Port numbers (TCP or UDP) ensure that packets are delivered properly. Both Network Address Translation (NAT) and Port Address Translation (PAT) are supported by this router. NAT and PAT are common solutions for: overcoming the shortage of public IP addresses, security (private IP addresses are not transparent), and assisting network administration.

The router supports many types of NAT functions, including:

Fixed-NAT: this maps a private IP address to a public IP address.

Multi-NAT: this maps multiple private IP addresses to multiple public IP address.

PAT: When private IP addresses are more than public IP addresses, port address translation is supported to translate the public IP addresses.

Note the usage of synonyms below:

Local: private, illegal, unregistered

Public: legal, registered

In PPPoE or PPPoA mode, the NAT function is automatically enabled. In RFC 1483 Routed mode, to enable NAT, you must select the Enable NAPT item on the WAN Setup screen.

The following pages describe how to set up a virtual server (Redirect port) and different types of NAT.

1740-A2-GB20-00

July 2004

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Contents Shdsl July 1740-A2-GB20-00 July Table of Contents Chapter Application Example Appendix a Specifications Application OverviewColor Mode Function LED IndicatorsFour-wire 8P8C straight-through RJ45 cable InstallationPreparing for Hardware Installation AC power adapterEthernet connection Power connectionRear-panel Connections DSL connectionLogin Quick InstallationJuly Web Page Layout Monitoring the Shdsl Line WAN Interface Configuration VCI Bridge Mode Service for One Fixed IP Address1740-A2-GB20-00 July Router Mode Service for Five Static IP Addresses 1740-A2-GB20-00 July July 1740-A2-GB20-00 July PPPoE Shdsl 2/4-Wire Router User’s Guide PPPoA 1740-A2-GB20-00 July Password Setup Spanning Tree Protocol Setting the BridgeStatic Bridging Write System Configurations Load Factory Default Values LAN Interface Setting up WAN and LAN InterfacesConfiguring the WAN Interface VC Data Flow Control Setting up an ISP Snmp Enable SnmpDisable Snmp Add a Packet Filter entry Packet FilterDelete a Packet Filter entry Enable/Disable Packet FilterModify RoutingStatic Route AddSet Up the RIP function 1740-A2-GB20-00 July Displaying the Routing Table NAT Multiple to One One to One NAT Multi-NAT 1740-A2-GB20-00 July Virtual Server Dhcp Server DhcpDhcp Relay DNS Proxy Igmp Click Apply to submit the settings Parameters and buttons VlanSoftware Upgrade and Configuration Backup /Restoration Maintenance and DiagnosticsJuly 1740-A2-GB20-00 July OAM Loopback Ping Performance Monitoring 1740-A2-GB20-00 July Interface Adding the Static Route Web Application ExampleJuly Line Port RJ45 Pin AssignmentsVT100 Compatible Terminal Console AccessConsole Port Cable Keyboard Operations July Motoring the Shdsl Line Status Disable the Web Browser Retrieve the Factory Default SettingsSave the Configurations July Appendix a Specifications Network functions Power SupplyEnvironmental Conditions