Freecom Technologies FSG-3 - Manual (Page 75)

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Networks and Routing Basics
This chapter provides an overview of IP networks, routing, and firewalls. This is
by no means a complete overview! If you are looking for more information, you
can use your favorite search engine to find information on the internet about
the internet. Suffice to say, there is plenty.
Basic Router Concepts
Even though the amount of bandwidth in your local area network (LAN) can be
provided easily and relatively inexpensively, the price of the connection to the
internet is much higher. Because of this expense, Internet access is usually
provided by a slower-speed wide-area network (WAN) link such as a cable or DSL
modem. To use this WAN link efficiently, a mechanism must be in place for
selecting and transmitting only the data traffic meant for the Internet. The
function of selecting and forwarding this data is performed by a router.
What is a Router?
A router splits the information meant for your network and meant for other
networks, so the available bandwidth is used efficiently. The router sends data
based on network layer information in the data and on routing tables main-
tained by the router. The routing tables are built by gathering and exchanging
information with other routers in the network. The router builds up a logical
picture of the overall network. Using this information, the router chooses the
best path for forwarding network traffic. Routers vary in performance and scale,
number of routing protocols supported, and types of physical WAN connection
they support.
Routing Information Protocol
One of the protocols used by a router to build and maintain a picture of the
network is the Routing Information Protocol (RIP). Using RIP, routers periodically
update one another and check for changes to add to the routing table.
IP Addresses and the Internet
For a computer to communicate with other computers and Web servers on the
Internet, it must have a unique IP address. An IP address (IP stands for Internet
Protocol) is a unique number that identifies the location of your computer on a
network.
Basically, it works like your street address — as a way to find out exactly where
you are and deliver information to you. The IP address is written as 4 numbers
between 0 and 256, such as "192.168.0.12".
Appendix