http://www.cisco.com/univercd/cc/td/doc/cisintwk/ito_doc/introwan.htm
Wide Area Network Assessment
Introduction to WAN's
Wide Area Networks (WAN's) are very large networks of computers. These networks span across large geographical areas and have been know to connect computers thousands of miles apart. A WAN can also be a collection of LANs, bringing together many smaller networks into one large network. Unlike LANs, most WAN's are not owned by any one organisation but exist under collective or distributed ownership and management. The Internet is the biggest WAN in existence today connecting millions of users across the world.
Basic concepts of WANs
WANs are built to provide communication solutions for organizations or people who need to exchange digital information between two distant places.
There are 5 main types of WAN communication in use today, these are:
Point to Point links
Circuit Switching
Packet Switching
WAN virtual circuit
WAN Dial up services
Point to Point links
A point-to-point link provides a pre-established WAN communications path from a home through a carrier network to a remote network.
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Classless Inter-Domain Routing
RITA networkThe price is based on bandwith required and distance between the 2 connection points.
Circuit Switching
A method of routing traffic between an originator and a destination through a Switching Centre where a continuous electrical circuit is established and maintained between the calling and called stations until it is released by one of those stations. ISDN is an example of circuit switching.
Packet Switching
Packet Switching is the opposite to Circuit Switching as packets are individually routed between node with no previously established communication path. The Internet is a Packet Switched network running the layer 3 Internet Protocol over a variety of other technologies.
WAN Virtual Circuits
A virtual circuit is a logical circuit created within a shared network between two network devices. There are currently 2 types of Virtual Circuits in existance...