Trab inlges tecnico

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Telecommunications network
From Wikipedia, the free encyclopedia

A telecommunications network is a collection of terminals, links and nodes which connect to enable telecommunication between users of the terminals. Each terminal in the network have a unique address so messages or connections can be routed to the correct recipients. The collection of addresses in the network is called the address space.
The links connect the nodes together and are themselves built upon an underlying transmission network which physically pushes the message across the link, using circuit switched, message switched or packet switched routing.
Examples of telecommunications networks are: * computer networks * the Internet * the telephone network * the global Telex network * the aeronautical ACARS network

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Messages and protocols

Example of how nodes may be interconnected with links to form a telecommunications network
Messages are generated by a sending terminal, then pass through the network of links and nodes until they arrive at the destination terminal. It is the job of the intermediate nodes to handle the messages and route them down the correct link toward their final destination.
These messages consist of control (or signaling) and bearer parts which can be sent together or separately. The bearer part is the actual content that the user wishes to transmit (e.g. some encoded speech, or an email) whereas the control part instructs the nodes where and possibly how the message should be routed through the network. A large number of protocols have been developed over the years to specify how each different type of telecommunication network should handle the control and bearer messages to achieve this efficiently..
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Components
All telecommunication networks are made up of five basic components that are