Network: A computer network is a system for communication between computers. Components of Networks: <ul><li>People. </li></ul><ul><li>Hard ware. </li></ul><ul><li>Software. </li></ul><ul><li>connectivity. </li></ul><ul><li>Procedure. </li></ul>
Local Area Network: A local area network is data communication system in a limited geographical area. Like a home, office, or small group of buildings
Metro-Politan Area Network: A Metro-politan area network is a network designed to extend over an entire city.
Wide Area Network: A wide area network provides long distance transmission of data over a large geographical areas Comprising a country,a continent or the whole world. The most well-known example of a WAN is the Internet.
Network Topology: . The logical layout of the cables and devices that connects the nodes of a computer.
Gateways: A Gateway is an interface permitting communication between dissimilar networks.
Other Devices: <ul><li>Multiprotocol Routers </li></ul><ul><li>Brouters </li></ul><ul><li>Switches </li></ul>
MULTIPROTOCOL ROUTERS: Multiprotocol routers have been designed to route packets belonging to two or more protocols
BROUTER: A Brouter is a single protocol or multi protocol router that sometimes acts as a router and sometimes as a bridge.
Switches : Switches are the hardware or software devices capable of creating temporary links between two or more devices linking to the switch but not to each.
Hubs: A Hub is the simple connection point for different type of devices on a network. It sends all the data to all devices connected to it.
Nodes: Any device that is attached to a network.A node may be a microcomputer,terminal,storage device or peripheral device which enhance the usefulness of the network.
Signals: The electronic transformation of data and information through a medium is called signal.
Types of Signals: <ul><li>Analog signal. </li></ul><ul><li>Digital signal. </li></ul>
Analog signals: The transformation of data in the form of waves.
Digital signals: The signals which travels in form of 0s and 1s .
Periodic signal: Periodic signals consist of a continuously repeated pattern.
Aperiodic signal: Aperiodic signals consist of a non repeated pattern.
Types of Analog signal: <ul><li>Simple signal. </li></ul><ul><li>Composite signal. </li></ul>
Simple Signal: A simple analog signals consist of a single sine wave or a single frequency signals.
Composite signals: The signals which composed of more than one sine waves having different frequencies.
Frequency spectrum and bandwidth: The frequency spectrum of a signals is the collection of all the component frequencies that it contain . The bandwidth of a signal is the width of frequency spectrum.
Digital Signal: The signals which travels in form of 0s and 1s .
Bit interval and bit rate: The bit interval is the time required to send a single bit. The bit rate is number of bit intervals per second,usually expressed in bits per second.