D-Link DI-206 User Manual - Appendix B - Ip Concepts

DI-206 ISDN Remote Router

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Appendix B - IP

Concepts

Appendix B - IP Concepts

This appendix describes some basic IP concepts, the TCP/IP addressing scheme and show

how to assign IP Addresses.

When setting up the router, you must make sure all ports to be utilized on the router have

valid IP addresses. Even if you will not use the ISDN or WAN ports, you should, at the very

least, make sure the LAN port is assigned a valid IP address. This is required for telnet, in-

band SNMP management, and related functions such as “trap” handling and TFTP firmware

download.

IP Addresses

The Internet Protocol (IP) was designed for routing data between network sites all over the

world, and was later adapted to allow routing between networks (often referred to as

“subnets”) within any site. IP includes a system by which a unique number can be assigned to

each of the millions of networks and each of the computers on those networks. Such a

number is called an IP address.

To make IP addresses easy to understand, the originators of IP adopted a system of

representation called “dotted decimal” or “dotted quad” notation. Below are examples of IP

addresses written in this format:

201.202.203.204        189.21.241.56        125.87.0.1

Each of the four values in an IP address is the ordinary decimal (base 10) representation of a

value that a computer can handle using eight “bits” (binary digits — 1s and 0s). The dots are

simply convenient visual separators.

Zeros are often used  as placeholders  in dotted  decimal notation; 189.21.241.56 can therefore

also appear as 189.021.241.056.

IP networks are divided into three classes on the basis of size. A full IP address contains a

network portion and a “host” (device) portion. The network and host portions of the address

are different lengths for different classes of networks, as shown in the table below.