Wide Area Network cont'd

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The collection of communication lines and routers form the subnet.When a packet is sent from 1 router to another via 1 or more intermediate routers,the packet is received at each intermediate router in its entirety, stored until required output line is free and then forwarded.A subnet organized according to this principal is called a store and forward packet switched subnet.
When packet are small and all the same size,they are often called cells.
Packet travelling bearing number in the sequence.
Not all WANs are packet switched. A second possibility for a WAN is a satellite system.
Each router has an antenna through which it can send and receive.All routers can hear the output from satellites.


Next: Wireless Network

Wide Area Network or WAN

WAN spans a large geographical area,often a country or continent. The job of the subnet is to carry messages from host to host,just as telephone system carries words from speaker to listener.
    In most wide area n/ws,the subnet consists of 2 distinct components : transmission lines & switching elements.
Transmission lines move bits between machines. They can be made of copper wire,optical fiber or even radio links.
When data arrive on an incoming line,the switching element must choose an outgoing line on which to forward them.
Switching element is also called router.


Next:WAN contn'd