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BASIC CONCEPTS OF NETWORK. INDEX. Definition & applications of computer network Components of computer network Network benefits Disadvantages of computer network Classification by their geographical area Network classification by their component role Types of servers.
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INDEX • Definition & applicationsof computer network • Components of computer network • Network benefits • Disadvantages of computer network • Classification by their geographical area • Network classification by their component role • Types of servers
DEFINTION & APPLICATIONS • DEFINTION: A computer network is defined as the interconnection of two or more computers. It is done to enable the computers to communicate and share available resources. • APPLICATIONS: • Sharing of resources such as printers • Sharing of expensive software's and database • Communication from one computer to another computer • Exchange of data and information among users via network • Sharing of information over geographically wide areas.
COMPONENTS OF COMPUTER NETWORK • Two or more computers • Cables as links between the computers • A network interfacing card(NIC) on each computer • Switches • Software called operating system(OS)
SHARING RESOURCES • Types of resources are: • Hardware: A network allows users to share many hardware devices such as printers , modems, fax machines, CD ROM, players, etc. • Software: sharing software resources reduces the cost of software installation, saves space on hard disk.
OTHER BENEFITS OF COMPUTER NETWORK • Increased speed • Reduced cost • Improved security • Centralized software managements • Electronic mail • Flexible access
DISDAVATAGES OF NETWORKS • High cost of installation • Requires time for administration • Failure of server • Cable faults
LOCAL AREA NETWORK(LAN) • LAN is a network which is designed to operate over a small physical area such as an office, factory or a group of buildings. • LAN’s are easy to design and troubleshoot • Exchange of information and sharing of resources becomes easy because of LAN. • In LAN all machines are connected to a single cable. • Different types of topologies such as star, tree, bus, ring, etc Can be used • It is usually a privately owned network.
WIDE AREA NETWORK(WAN) • When network spans over a large distance or when the computers to be connected to each other are at widely separated locations, a local area network cannot be used. A wide area network(WAN) is installed. • The communication between different users of WAN is established using leased telephone lines, satellite links and similar channels. • It is cheaper and more efficient to use the phone network for the link. • Most WAN networks are used to transfer large blocks of data between its users.
METROPOLITAN AREA NETWORK(MAN) • It is in between LAN & WAN technology that covers the entire city. • It uses similar technology as LAN. • It can be a single network such as cable TV network, or a measure of connecting a number of LAN’s o a large network so that resources can be shared LAN to LAN as well as device to device.
COMPUTER HARDWARE • When we refer to network hardware, we are talking about a range of electronic devices that can be interconnected in such a way as to allow the transmission of communication signals between a number of workstations. • These devices range from simple generic hubs to sophisticated proprietary hardware such as routers and gateways.
Network Interface Cards • Network Interface Cards (NICs) are the most common type of network hardware on a network. • Every computer on network will contain at least one NIC. • NICs contain the electronic components that establish and control network communications. • The NIC is the principal hardware device that differentiates between a networked computer and a stand-alone computer.
Hubs • Hubs are one of the most basic pieces of networking equipment available. • Physically a hub is a box with a number of RJ45 ports (typically between 4 and 32) that allows you to connect several networking devices together using twisted pair (CAT 5) network cables.
Hubs • Hubs have no intelligence, meaning they cannot be programmed or have a memory of devices that are plugged into its ports. • They are quite suitable for small networks but tend to perform poorly on large networks.
Switches • Switches look nearly identical to hubs, but a switch generally contains more ‘intelligence’ than a hub. • Unlike hubs, network switches are capable of inspecting the data packets as they are received, determining the source and destination device of that packet, and forwarding that packet appropriately.
Switches • By delivering messages only to the connected device that it was intended for, network switches conserve network bandwidth and offer generally better performance than hubs. • Most switches are active: that is, they electrically amplify the signal as it moves from one device to another.
Bridges • Bridges are devices that allow you to segment a large network into two small, more efficient networks. • If you are adding an older wiring scheme and want the new network to be up-to-date, a bridge can connect the two.
Bridges • A bridge monitors the information traffic on both sides of the network so that it can pass packets of information to the correct location. • Most bridges can ‘listen’ to the network and automatically figure out the address of each computer on both sides of the bridge. • The bridge can inspect each message and, if necessary, broadcast it on the other side of the network.
Routers • Routers translate information from one network to another; it is similar to a bridge with extra intelligence. • Routers select the best path to route a message, based on the destination address and origin. • The router can direct traffic to prevent head-on collisions, and is smart enough to know when to direct traffic along back roads and shortcuts.
Routers • While bridges know the addresses of all computers on each side of the network, routers know the addresses of computers, bridges, and other routers on the network. • Routers can even ‘listen’ to the entire network to determine which sections are busiest - they can then redirect data around those sections until they clear up.