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INTRODUCTION
Computer networking is a group of computer and devices interconnected by communications channels that allows users to share information and resources as hard drives, printers, scanners and others with each other.There are two types of network which is peer to peer and client to server.
 * A network refer as peer and peer networking if most computer are similar and run workstation operator.It typically has a mix of Microsoft Windows 9X, Me, Windows XP Homes Addition, or Windows XP Professional.In a peer-to-peer network, each computer holds its files and resources. Other computers can access these resources but a computer that has a particular resource must be turned on for other computers to access the resource it has.
 * A computer network is referred to as client to server if (at least) one of the computers is used to "serve" other computers referred to as "clients". Besides the computers, other types of devices can be part of the network.In a client/server environment, each computer still holds (or can still hold) its (or some) resources and files. Other computers can also access the resources stored in a computer, as in a peer-to-peer scenario. One of the particularities of a client/server network is that the files and resources are centralized. This means that a computer, the server, can hold them and other computers can access them. Since the server is always On, the client machines can access the files and resources without caring whether a certain computer is On.Another big advantage of a client/server network is that security is created, managed, and can highly get enforced. To access the network, a person, called a user must provide some credentials, including a username and a password. If the credentials are not valid, the user can be prevented from accessing the network.The client/server type of network also provides many other advantages such as centralized backup, Intranet capability, Internet monitoring, etc.In these series of lessons, the network we will build is based on Microsoft Windows operating systems.

BACKGROUND
A network is a collection of compatible hardware and software arranged to communicate information (text, graphics, voice, or video) from one computer to others or to peripheral equipment such as printers. Among other purposes, computer networks are used to increase communications and share data files orequipment such as scanners.Networks vary in complexity. Simple networks may link several PCs anda printer. More sophisticated “client/server” computing is widely used to distribute the task of inputting data to various “client” software and computers and centralize data storage and processing in one or more “server” computers,managed by the server software. A network can serve a few computers in a room, dozens of computers in a building, or several different governmental units crossing several countries. Local-area networks or LANs are limited in range to a few thousand feet (although fiber optic cables are expanding the range). Wide-area networks or WANs connect multiple sites or computer networks at high speed across a broad geographic area using switched and dedicated lines (wire, cable, or fiber), microwave, or satellite communications.

BENEFIT
Computer network provide us a lot advantages. Such benefits are :
 * 1) Facilitating communication. Using a network, people can communicate efficiently and easily via email, instant messaging, chat rooms, telephone, video telephone calls, and video conferencing.It had shorten the distance.
 * 2) Sharing hardware. In a networked environment, each computer on a network may access and use hardware resources on the network, such as printing a document on a shared network printer.
 * 3) Files, data, and information can be sharing efficiently. In a network environment, authorized user may access data and information stored on other computers on the network. The capability of providing access to data and information on shared storage devices is an important feature of many networks.People can send their files from one computer to another easily.Users can create files and store them in one computer then access those files from other computers connected to it.
 * 4) Sharing software. Users connected to a network may run application programs on remote computers.Users can run their programs which are not installed on their computers but are installed on any other user's computer.
 * 5) Save time.Users can done their works and search for the information that they want within a short time by just connecting the network.
 * 6) Save money.You can connect all the computers which are connected through a network to the internet by using a single line. So it means that you can save the connection cost for each computer but you internet connection must be fast.

The following list presents categories used for classifying networks
Connection Method Computer networks can be classified according to the hardware and software technology that is used to interconnect the individual devices in the network, such as optical fiber, Ethernet, wireless LAN, HomePNA, power line communication or G.hn.Ethernet uses physical wiring to connect devices. Frequently deployed devices include hubs, switches, bridges, or routers. Wireless LAN technology is designed to connect devices without wiring. These devices use radio waves or infrared signals as a transmission medium. ITU-TG.hn technology uses existing home wiring (coaxial cable, phone lines and power lines) to create a high-speed (up to 1 Gigabit/s) local area network.

Wired Technology
 * Twisted pair wire is the most widely used medium for telecommunication. Twisted-pair wires are ordinary telephone wires which consist of two insulated copper wires twisted into pairs and are used for both voice and data transmission. The use of two wires twisted together helps to reduce crosstalk and electromagnetic induction. The transmission speed ranges from 2 million bits per second to 100 million bits per second.
 * Coaxial cable is widely used for cable television systems, office buildings, and other worksites for local area networks. The cables consist of copper or aluminum wire wrapped with insulating layer typically of a flexible material with a high dielectric constant, all of which are surrounded by a conductive layer. The layers of insulation help minimize interference and distortion. Transmission speed range from 200 million to more than 500 million bits per second.
 * Optical fiber cable consists of one or more filaments of glass fiber wrapped in protective layers. It transmits light which can travel over extended distances. Fiber-optic cables are not affected by electromagnetic radiation. Transmission speed may reach trillions of bits per second. The transmission speed of fiber optics is hundreds of times faster than for coaxial cables and thousands of times faster than a twisted-pair wire.

Wireless Technologies
 * Terrestrial microwave – Terrestrial microwaves use Earth-based transmitter and receiver. The equipment look similar to satellite dishes. Terrestrial microwaves use low-gigahertz range, which limits all communications to line-of-sight. Path between relay stations spaced approx, 30 miles apart. Microwave antennas are usually placed on top of buildings, towers, hills, and mountain peaks.
 * Communications satellites – The satellites use microwave radio as their telecommunications medium which are not deflected by the Earth's atmosphere. The satellites are stationed in space, typically 22,000 miles (for geosynchronous satellites) above the equator. These Earth-orbiting systems are capable of receiving and relaying voice, data, and TV signals.
 * Cellular and PCS systems – Use several radio communications technologies. The systems are divided to different geographic areas. Each area has a low-power transmitter or radio relay antenna device to relay calls from one area to the next area.
 * Wireless LANs – Wireless local area network use a high-frequency radio technology similar to digital cellular and a low-frequency radio technology. Wireless LANs use spread spectrum technology to enable communication between multiple devices in a limited area. An example of open-standards wireless radio-wave technology is IEEE.
 * Infrared communication, which can transmit signals between devices within small distances not more than 10 meters peer to peer or ( face to face ) without any body in the line of transmitting.

Scale Networks are often classified as local area network (LAN), wide area network (WAN), metropolitan area network (MAN), personal area network (PAN), virtual private network (VPN), campus area network (CAN), storage area network (SAN), and others, depending on their scale, scope and purpose, e.g., controller area network (CAN) usage, trust level, and access right often differ between these types of networks. LANs tend to be designed for internal use by an organization's internal systems and employees in individual physical locations, such as a building, while WANs may connect physically separate parts of an organization and may include connections to third parties.

Network Topology Main article: Network topology Computer networks may be classified according to the network topology upon which the network is based, such as bus network, star network, ring network, mesh network. Network topology is the coordination by which devices in the network are arranged in their logical relations to one another, independent of physical arrangement. Even if networked computers are physically placed in a linear arrangement and are connected to a hub, the network has a star topology, rather than a bus topology. In this regard the visual and operational characteristics of a network are distinct. Networks may be classified based on the method of data used to convey the data, these include digital and analog networks.

TWO TYPES OF NETWORKS BASED ON PHYSICAL SCOPE
Local area network(LAN) Wide Area Network(WAN)
 * Local area network (LAN) is a network that connects over a relatively small geographical are, typically connecting computers within a single office or building. In most cases they connect to a common electronic connection- commonly known as a network backbone. LAN's can connect to other networks either directly or through a WAN or MAN.The defining characteristics of LANs, in contrast to WANs (Wide Area Networks), include their higher data transfer rates, smaller geographic range, and no need for leased telecommunication lines.


 * A wide area network (WAN) is a computer network that covers a large geographic area such as a city, country, or spans even intercontinental distances, using a communications channel that combines many types of media such as telephone lines, cables, and air waves. A WAN often uses transmission facilities provided by common carriers, such as telephone companies. WAN technologies generally function at the lower three layers of the OSI reference model: the physical layer, the data link layer, and the network layer.

BASIC HARDWARE COMPONENTS

1. Network interface cards
- A network card, network adapter, or NIC (network interface card) is a piece of computer hardware designed to allow computers to communicate over a computer network. It provides physical access to a networking medium and often provides a low-level addressing system through the use of MAC addresses.

[edit]2. Repeaters
- A repeater is an electronic device that receives a signal, cleans it of unnecessary noise, regenerates it, and retransmits it at a higher power level, or to the other side of an obstruction, so that the signal can cover longer distances without degradation. In most twisted pair Ethernet configurations, repeaters are required for cable that runs longer than 100 meters. Repeaters work on the Physical Layer of the OSI model.

[edit]3. Hubs
- A network hub contains multiple ports. When a packet arrives at one port, it is copied unmodified to all ports of the hub for transmission. The destination address in the frame is not changed to a broadcast address. It works on the Physical Layer of the OSI model.

[edit]4. Bridges
- A network bridge connects multiple network segments at the data link layer of the OSI model. Bridges broadcast to all ports except the port on which the broadcast was received. However, bridges do not promiscuously copy traffic to all ports, as hubs do, but learn which MAC addresses are reachable through specific ports. Once the bridge associates a port and an address, it will send traffic for that address to that port only. - Bridges learn the association of ports and addresses by examining the source address of frames that it sees on various ports. Once a frame arrives through a port, its source address is stored and the bridge assumes that MAC address is associated with that port. The first time that a previously unknown destination address is seen, the bridge will forward the frame to all ports other than the one on which the frame arrived. - Bridges come in three basic types:
 * Local bridges: Directly connect local area networks (LANs)
 * Remote bridges: Can be used to create a wide area network (WAN) link between LANs. Remote bridges, where the connecting link is slower than the end networks, largely have been replaced with routers.
 * Wireless bridges: Can be used to join LANs or connect remote stations to LANs.

[edit]5. Switches
- A network switch is a device that forwards and filters OSI layer 2 datagrams between ports based on the MAC addresses in the packets. A switch is distinct from a hub in that it only forwards the frames to the ports involved in the communication rather than all ports connected. A switch breaks the collision domain but represents itself as a broadcast domain. Switches make forwarding decisions of frames on the basis of MAC addresses. A switch normally has numerous ports, facilitating a star topology for devices, and cascading additional switches. Some switches are capable of routing based on Layer 3 addressing or additional logical levels; these are called multi-layer switches. The term switch is used loosely in marketing to encompass devices including routers and bridges, as well as devices that may distribute traffic on load or by application content.

[edit]6. Routers
- A router is an internetworking device that forwards packets between networks by processing information found in the datagram or packet. In many situations, this information is processed in conjunction with the routing table. Routers use routing tables to determine what interface to forward packets.

=CONCLUSIONS=

In conclusion, the introduction and the advancement of technology in networking had improve the lifestyle of everyone. With all these networks, we are able to transfer information from one to another either through a wired or wireless network. With the enhance and advancement of the network use in our daily life, connecting someone far away like 1000 miles can be ease.