ABSTRACT
Optical-fibre communications technology became available to bring the connection to the residential areas. Optical wireless comes into play because it complements fibre optics in metro area networks and local area networks (LANs), with considerably less expense and faster deployment. This chapter discusses basic communication systems. The following are basic terms used for the networks used in communication systems: Station, Network, Topology, Switching, Routing and Protocol. A popular protocol used in optical LANs is the fibre-distributed data interface (FDDI) protocol; SONET/SDH protocols are used in optical networks in metro or wider areas. Logical topologies are bound to the network protocols that direct how the data moves across a network. Connections between the nodes are via optical couplers. The five most common network topologies are: bus topology, ring topology, star topology, mesh topology and tree topology. The chapter then presents an open-system interconnection (OSI) a model that defines a networking framework used for implementing protocols in seven layers of communications.
