What You Will Choose

WHAT YOU WILL CHOOSE

Before configuring the modem, consider the options in the following “Configuration” section. Ensure that you have the appropriate power cable for your facility as described below in the “Power Cable” section.

Configuration

You can choose to use:

•Network Address Translation (NAT) protocol. This protocol includes both basic NAT and Network Address Port Translaton (NAPT). Basic NAT uses a one-to-one mapping of a private IP address and a public IP address. NAPT uses a multiple-to-one mapping of multiple IP addresses and their ports to a single IP address and its ports. For more information about the NAT protocol, see “NAT” on page 87.

•Domain Name System (DNS) resolution. You must specify the IP address for a device to serve as the DNS resolver. You can also specify a second IP address to designate another device to serve as a secondary DNS resolver. The DNS device maps human-readable addresses to IP addresses. For simplicity and ease of management, use DNS relay. DNS relay allows the LAN hosts to configure the Megabit Modem as the DNS server. Depending on the host sending the DNS message and what session it is assigned to, the Megabit Modem will relay the message to the appropriate DNS server. For more information about DNS resolution, see “DNS Resolution” on page 93.

•TFTP server for downloading software updates to the modem. You specify the IP address, subnet mask, and directory path (where software updates are located) for the device that will be the TFTP server.

Power Cable

The Megabit Modem 400F, 500L, 600F, and 700F are available with a variety of power supplies and power cords. When you order your modem, choose one of the following as the last number in the product part number (example: use 150-2122-7xfor the 700F) for your order to indicate which power option you need:

•2 indicates a power supply for International use and does not include a power cord.

•3 indicates a power supply for North American use and includes a North American power cord.

•4 indicates a Universal power supply and includes a European power cord.

•5 indicates a Universal power supply and includes a UK/Ireland power cord.

14

Megabit Modem 400F, 500L, 600F, and 700F User Manual