What is a router, Ip addresses and the internet – NETGEAR ME103 User Manual

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Reference Manual for the ME103 802.11b ProSafe Wireless Access Point


Network, Routing, Firewall, and Cabling Basics

August 2003

What is a Router?

A router is a device that forwards traffic between networks based on network layer information in
the data and on routing tables maintained by the router. In these routing tables, a router builds up a
logical picture of the overall network by gathering and exchanging information with other routers
in the network. Using this information, the router chooses the best path for forwarding network

Routers vary in performance and scale, number of routing protocols supported, and types of
physical WAN connection they support. The ME103 802.11b ProSafe Wireless Access Point is a
small office router that routes the IP protocol over a single-user broadband connection.

IP Addresses and the Internet

Because TCP/IP networks are interconnected across the world, every machine on the Internet must
have a unique address to make sure that transmitted data reaches the correct destination. Blocks of
addresses are assigned to organizations by the Internet Assigned Numbers Authority (IANA).
Individual users and small organizations may obtain their addresses either from the IANA or from
an Internet service provider (ISP). You can contact IANA at www.iana.org.

The Internet Protocol (IP) uses a 32-bit address structure. The address is usually written in dot
notation (also called dotted-decimal notation), in which each group of eight bits is written in
decimal form, separated by decimal points.

For example, the following binary address: 11000011 00100010 00001100 00000111

is normally written as:

The latter version is easier to remember and easier to enter into your computer.

In addition, the 32 bits of the address are subdivided into two parts. The first part of the address
identifies the network, and the second part identifies the host node or station on the network. The
dividing point may vary depending on the address range and the application.

There are five standard classes of IP addresses. These address classes have different ways of
determining the network and host sections of the address, allowing for different numbers of hosts
on a network. Each address type begins with a unique bit pattern, which is used by the TCP/IP
software to identify the address class. After the address class has been determined, the software
can correctly identify the host section of the address. The follow figure shows the three main
address classes, including network and host sections of the address for each address type.