An interconnected set of two or more computers may be called a "Computer Network". A computer that is not connected to other computers is a "Stand-alone system".
Basic Advantages of Using Networks
There are many possible advantages in using networks. The basic ones are:
a) The sharing of resources (e.g. computers and staff) and information.
b) The provision of local facilities without the loss of central control
c) The even distribution of work d. Improved communication facilities
CATEGORIES OF NETWORKS
Networks can be grouped into three. They are; Local Area Network, Metropolitan Area Network and Wide Area Network.
Local Area Network (LAN): this is the network of computer that provides coverage within a building. Computers within an office or building are interconnected to share information. Here no public regulatory body's permission is required for the connection.
Metropolitan Area Network (MAN):These are networks that cover a city. It can be seen as various LAN connected within a city to share information. Here public regulatory body's permission is required.
Wide Area Network (WAN):These are networks that cover nation and international.
COMPONENTS OF NETWORK
There are three basic hardware components for a data communication network: Server or host computer: A server is a machine that provides clients with service. Servers share a specific resource with other computers. Examples of the servers are the database server, that provides the large database and the communication server that provides connection to another network, to commercial database, or to a powerful processor. There are file, database, network, access, modem, facsimile, printer, and geteway server. Servers are usually microcomputers (often more powerful than the other microcomputers on the network), but they may be minicomputers or mainframes.
Client: A client is a computer such as a PC or a workstation attached to the network, which is used to access shared network resources. Client computer uses the resources shared by server computer. There are three major categories of clients: terminals, minicomputers/workstation, and special purpose terminals.
Circuit: The circuit is the pathway through which the message passes. Circuits can be twisted pair cable, coaxial cable, fiber optic cable, microwave transmission, and so forth. There are many devices in the circuit that perform special functions, such as hubs, switches, routers and gateways.
NETWORK TOPOLOGIES
Computer networks can be categorized according to their physical shape or topology. Each terminal in a network is known as a node. If a central computer controls the network it is known as the host computer. The topology of a network is the arrangement of the nodes and the ways they are interconnected. The communication system within a network is known as the subnet. The various network topologies are;
Star Topology:this means that each node is connected, by separate connections to a computer at the centre. The star is a popular topology for WAN.
Ring Topology: this is specifically designed to use with LAN. Here all the nodes are connected in a ring form as illustrated below. Messages in ring network flow in one direction, from node to node in anticlockwise. The ring consists of repeaters, which are joined by the physical transmission medium. They have no host and none of the nodes need have overall control of access to the network.
Bus Topology:With bus topology, the workstations are connected to main cable (known as the bus or trunk), along which data travels. The ends of a bus are not connected, so that data has to travel in both directions to reach the various nodes on the network. The main bus standard is known as Ethernet. The term station tends to be
used rather than node for this type of network.
0 Comments