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Computer Network A computer network is a cluster of computers which are linked with each other Through communication channels for sharing data. Here are some terms that we need To understand before learning computer networking. Server: A server is a computer or the electronic device which connects all different computers with each other. It can be used to store information that is to be shared by all the computers on the network. Node: A node is a computer or an electronic device that is attached to the network. It Is also known as client or workstation.
TOPOLOGIES • It refers to the physical layout or pattern in which various computers in a computer network are connected to one another to form a network. • The computers in a network are also referred to as nodes. • Star Topology • RingTopology • BusTopology • HybridTopology • TreeTopology • Line Topology
BUS Topology In bus topology , all devices are connected with a single cable but , unlike line topology , individual nodes are connected to the main cable thought network interface connectors. If somehow , main cable break anywhere in the middle , the whole network breaks whereas if the individual cable break, then system continues to function.
Star Topology • In this topology , all nodes are connected to one central connection point. Since each node has an individual network, break in the cable would not affect the entire network. • Each machine is connected toa central hub orswitch. • All of the traffic which transversesthe network passes through the central hub. • The hub acts as a signal boosteror repeater which in turn allows the signal to travel greaterdistances. • Most widelyimplemented • Hub is the single point offailure
Ring Topology In ring topology, each computer is connected with two other computers so as to form a closed ring- like structure. In this topology the break -down of any one computer on a ring can disable the entire system or network.
Tree topology • Tree: A collection of busses connected by a branching cable with no closedloops • Allows users to create networks usingbridges • Message from any site can be received byall other sites, until it reaches an endpoint • End point controller absorbs a message ifit reaches end point controller without being accepted by ahost • Advantage: Message traffic can still flow through the network even if a single nodefails • In this type of topology, some nodes as individual servers and have branches giving shape like tree. A break in a branch does not affected the entire network
Hybrid topology Selects among the strong points of each topology and combines themto meet that system’s communications requirements mosteffectively Figure : Hybrid topology combining a star and aring usinga bridge
Hybrid (continued) Figure : Hybrid topology combining a star and abus
Mesh topology • In A mesh network each station is connected directly to every other station in thenetwork. • It is a viable solution only for smallernetworks. • The huge cabling cost and awkwardness of laying so many direct links make the mesh topology unattractive for LAN’s with a large number ofstations. • On the other hand since all stations are directly linked to all other stations on exclusive links, thistopologyallows simultaneous communications between a number of pairs of stations.
Line topology In line topology ,all devices are connected to each other in lines. It is the Simplest type of topology. It must be noted that if a cable breaks some where In the middle, the whole network breaks.
