Appendix B: Ip Concepts - D-Link DSL-504T Manual

DSL-504T User's Manual

Appendix B: IP Concepts

This appendix describes some basic IP concepts, the TCP/IP addressing scheme and
shows how to assign IP Addresses.
When setting up the Router, you must make sure it has a valid IP address. Even if you
will not use the WAN port (ADSL port), you should, at the very least, make sure the
Ethernet 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 for routing data between networks within any site
(often referred to as "subnetworks" or "subnets"). 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:
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.
Networks attached to the Internet are assigned class types that determine the maximum
number of possible hosts per network. The previous figure illustrates how the net and
host portions of the IP address differ among the three classes. Class A is assigned to
networks that have more than 65,535 hosts; Class B is for networks that have 256 to
65534 hosts; Class C is for networks with less than 254 hosts.
D-Link Systems, Inc.
201.202.203.204 189.21.241.56 125.87.0.1
App.B: IP Concepts
90