1. LAN Local Area Network
By Amal Wali 10DD

2. Contents Terms Advantages Disadvantages Cabled LAN, 3 types
Essential hardware
LAN topologies
3 structures of topologies
Bus topology
Star topology
Wireless LAN
WAN
Data transmission
Bibliography

3. Terms
Network: It is a collection of hardware components that are interconnected allowing information to be shared.
Standalone: It is a computer that does not require a network to function.
LAN: Local Area Network. Is a computer network that interconnects computers in a limited area, such as home, school or the library.
WAN: Wide Area Network. Is a telecommunication network that covers a wide area.
Clients: An application or system that accesses a service provided by a server.
Client/ Server Network: Involves numerous clients connecting to a single, central server.
Peer to peer network: Computer network in which each computer can act as a client or server for the other computers in the network.
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4. Advantages Costly hardware can be shared.
Network software is cheaper than purchasing individual packages.
Same files can accessed by all users.
Messages can be sent between clients.
Single internet connection can be shared by clients.
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5. Disadvantages Expensive to set up and maintain.
Viruses can spread to all computers in the network.
More prone to hacking due to multiple points of access.
If it is a star network, if the file server goes down, the whole network will go down.
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6. 3 types of Cabled LAN Cabled LAN is not wireless, but requires wires.
Twisted pair: copper wires twisted into pairs.
Coaxial cable: consist of copper or aluminum wire surrounded by an insulating layer.
ITU-T G.hn: uses existing home wiring to create high speed LAN.
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7. Essential hardware for a computer to be connected to LAN
Hub/Switch- interconnected multiple devices to LAN.
Router- distribute shared internet access from WAN to LAN.
NIC (Network Interface Card)
Cabling
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8. LAN topologies
LAN topologies is the layout pattern of interconnections of the numerous fundamentals of a computer network.
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9. 3 Structures of Topologies
Bus Topology: use a common backbone to connect all devices.
Ring Topology: has two neighbors for communication purposes.
Star Topology: a central connection point named a “hub node” that may be network hub, switch or router.
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10. Bus Topology
1- Best suited for small networks. 2- Easy to handle and use.
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11. Star topology
Advantages: 1- Easy to connect new devices. 2- Centralized management, helps monitor the network. 3- Failure of one nod does not affect the rest of the network. Disadvantages: 1- If the central device fails, the rest of the network goes down. 2- The overall cost of the network is increased due to the use of hubs, a router or switch as a central device. 3- Performance and the number of nodes that can be added to the network all depend on the capacity of the central device.
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12. Wireless LAN
WLAN links two or more devices with a delivery method which is usually OFDM radio or spread-spectrum, and usually provides a connection through an access point to the wider internet. This gives the user to move around freely within the local coverage area and still be connected to the network. Norman Abramson created the first wireless computer connection network. WLAN is usually used instead of LAN because of its ease.
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13. WAN
Wide Area Network is a telecommunication network that covers a broad area. Businesses and governments use WANs to relay data among employees, clients, buyers, and suppliers from various different regions. WAN has made it possible for companies to communicate internally in methods which did not exist before. A user of WAN must subscribe to a service through a telecommunication provider. 
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14. Data Transmission 
Data transmission is the physical transfer of data over a point-to-point channel. Examples would include copper wires, optical fibers, wireless communication and storage media. The data is represented as an electromagnetic signal, such as an electrical voltage, radiowave, microwave or infrared signal. Digital communications is the transfer of discrete messages. These messages are either represented by a sequence of pulses by means of line code, or by using a digital modulation method. Data transmitted may be digital messages coming from a data source, or it may be an Analog signal such as a phone call or a video signal. The source of coding and decoding is carried out by codec equipment. 
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15. Bibliography BACK http://en.wikipedia.org/wiki/Data_transmission
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