LAN Components

There are five basic components to an LAN.

• Server: A server is a computer in a network that shared by multiple users. There are many kinds of servers in dedicated server networks. For example, file servers, printer servers, and communication servers are they.

• Client Computer: In a communications network, the client computer is the requesting machine from the supplying machine, server.

• NIC: The Network Interface Card (NIC) is a printed circuit board that plugs into a network server or client computer. It enables the computer to be physically connected to the network cable, which provides the physical layer connection among the computers in the network. The NIC performs the electronic functions of the access method, or data link protocol, such as Ethernet, Token Ring and LocalTalk.

• Network Cables/Hubs: Network cable physically connects each computer to the other computers in the network. The selection of an LAN topology can be influenced greatly by the type of cable.
  • Network Cable: Most LANs use a combination of unshielded twisted pair (UTP) wires, shielded twisted pair (STP), coaxial cable, and fiber optic cable. The advantage of the shielded and unshielded twisted pair wires is in the low cost. Coaxial cable is also commonly used and physically larger and heavier than twisted pairs. The fiber optic cable is thin and light. Its high capacity makes it perfect for backbone networks. It is beginning to use fiber optic cable for LANs.

  • Network Hubs: A network hub is called in many different names such as concentrator, multistation access unit, transceiver, or repeater. It serves two purposes. First, they provide an easy way to connect network cables. Second, hubs act as repeaters or amplifiers.

  • Wireless LANs: Wireless LAN is an alternative method of cabling a local area network. They use the same protocols as other LANS, but they deliver data and information through the air rather than through physical cable. Wireless LAN offers an alternative for an old building where wiring is difficult and expensive. It provides new capability for mobile computing for laptop computers. Its disadvantages are the noise and insecurity.

• NOS: The NOS (network operating system) is the control program that resides in a server or workstation within an LAN. This controls the network. The NOS handles the requests for data from all the users on the networks. It is responsible for data link layers and the network layers. It must interact with the application programs and the computer's own operating system.
  One of the well-known NOS for microcomputer is a NetWare. This is an NOS from Novell, Inc. This runs on 286 and higher personal computers and supports DOS, OS/2 and Macintosh operating system. It also supports many LAN access methods such as Ethernet, Token Ring, ARCNET and Starlan.