Networks can be classified by their topology, which is the basic geometric arrangement of the network. Different types of network configurations exist for network designers to choose from. Communications channels can be connected in different arrangements using several different topologies. This arrangement allows users to exchange information and share resources (software and hardware).
Four basic types of network configurations are star, bus, ring, hierarchical and mesh. Ring, bus, and star topologies are commonly used in LANs and BNs. Star and mesh topologies are commonly used in MANs and WANS. The networks are usually built using a combination of several different topologies.
A star topology is one in which a central unit provides a link through which a group of smaller computers and devices is connected.The central computer is commonly called a host computer. A host computer is usually a large computer such as a minicomputer or a mainframe. A file server is a large storage device that provides volumes of data and programs to the other units in the network.
In the star network, all interactions between different computers in the network travel through the host computer. The central unit will poll each to decide whether a unit has a message to send. If so, the central computer will carry the message to the receiving computer.
Star networks represent a very popular form of configuration for time-sharing systems in which a central computer makes available resources and databases for several "client" computers to share. As such, the star network is appropriate for systems that demand centralized control. The disadvantage of the star network is that a processing problem in the central computer can be paralyzing to the entire system.
In a star network, the central unit may be a host computer or a file server. The host computer is a large centralized computer, usually a minicomputer or a mainframe. In contrast, the file server is a large-capacity hard-disk storage device. It stores data and programs files shared by the users on the network. Also, called a network server.
