LAN Hardwares and Softwares

To realize a LAN process, several functions are to be performed. They require hardware and software specially built for such purpose. Some of the basic hardware and software components of LAN include

• Network Interface Controller ( NIC )
• Servers
• LAN Software / Operating System ( NOS )

Network Interface Controller ( NIC ):

 

A network interface card (or) network adapter (or) network interface controller (or) LAN adapter is a computer hardware component that interfaces to a computer network. 

Purpose :

The NIC Card allows computers to communicate over a computer network. It is both an OSI layer 1 (physical layer) and layer 2 (data link layer) device, as it provides physical access to a networking medium and provides a low-level addressing system through the use of MAC addresses. It allows users to connect to each other either by using cables or wireless.

Every Ethernet network card has a unique 48-bit serial number called a MAC address, which is stored in ROM carried on the card. Every computer on an Ethernet network must have a card with a unique MAC address. Normally, it is safe to assume that no two network cards will share the same address, because card vendors purchase blocks of addresses from the Institute of Electrical and Electronics Engineers (IEEE) and assign a unique address to each card at the time of manufacture.

Whereas network cards used to be expansion cards that plug into a computer bus, the low cost and ubiquity of the Ethernet standard means that most newer computers have a network interface built into the motherboard. These either have Ethernet capabilities integrated into the motherboard chip-set or implemented via a low cost dedicated Ethernet chip, connected through the PCI (or the newer PCI express) bus. A separate network card is not required unless multiple interfaces are needed or some other type of network is used. Newer motherboards may even have dual network interfaces built-in

Implementation :

The card implements the electronic circuitry required to communicate using a specific physical layer and data link layer standard such as Ethernet or token ring. This provides a base for a full network protocol stack, allowing communication among small groups of computers on the same LAN and large-scale network communications through routable protocols, such as IP.
There are four techniques used to transfer data, the NIC may use one or more of these techniques.

• Polling is where the microprocessor examines the status of the peripheral under program control.
• Programmed I/O is where the microprocessor alerts the designated peripheral by applying its address to the system's address bus.
• Interrupt-driven I/O is where the peripheral alerts the microprocessor that it's ready to transfer data.
• DMA is where an intelligent peripheral assumes control of the system bus to access memory directly. This removes load from the CPU but requires a separate processor on the card.

A network card typically has a RJ45, BNC, or AUI socket where the network cable is connected, and a few LEDs to inform the user of whether the network is active, and whether or not there is data being transmitted on it. Network cards are typically available in 10/100/1000 Mbit/s varieties. This means they can support a notional maximum transfer rate of 10, 100 or 1000 Megabits per second.
Sometimes the words 'controller' and 'card' are used interchangeably when talking about networking because the most common NIC is the network interface card. Although 'card' is more commonly used, it is less encompassing. The 'controller' may take the form of a network card that is installed inside a computer, or it may refer to an embedded component as part of a computer motherboard, a router, expansion card, printer interface or a USB device.

Servers :

One of the major advantage of LAN is sharing resources such as storage device, printer etc. This is enabled by providing servers on the LAN. Server is a dedicated computer which controls one or more resources. Two major categories of servers used in LAN are :

• File Server
• Print Server

Networking file server is used to share storage spaces for files. In addition to providing storage apace for files, file server is used to take periodic backup and also provide access to another server within and between LANs.
Same way print server is used to handle printing operations of all workstations connected in the network.

LAN Software / Operating System :

Network Operating System (NOS) is a software application required to control the use of LAN standards. Every NOS provides two sets of software, one is server and client software. Server software runs the network server and client server runs network client. 

Server software enables file server, print server, database server to operate.
Ex.: Windows NT Server, Novell Net-ware

Client software must interact with application layers and computer's own operating system. Some application allow users to share data files and access shared data.
Ex.: Windows NT Workstation, Windows 2000 Professional, Windows XP etc.