LAN is an acronym for Local Area Network which is a network designed to operate over a small physical area such as an office,factory or a group of buildings. They are privately owned networks which are limited in size.
LAN’s are widely used to connect computers and workstations in company offices and factories to share resources such printers,scanners etc. and to exchange information. Depending on the needs of an organisation and the type of technology used, a LAN can be as simple as connection of two personal computers and a printer in someone’s office or home or it can extend throughout a company and include voice, sound, and video peripherals.
In LAN all the machines are connected to a single cable. Different types of topologies such as BUS, Ring, Star, Tree etc. are used for LANs. They are easy to design and troubleshoot.
One of the computers in a network can become a server serving all the remaining computers called clients. For example a software can be stored on the server and it can be used by the remaining clients. In a LAN its size can be determined by licensing restrictions on the number of users per copy of software or by restricting the number of users licensed to access the operating system.
LAN uses a layered architecture and they are capable of operating at hundreds of Mbits/sec. Traditional LANs run at the speed of 10 Mbps to 100 Mbps and newer LANs operate at upto 10 Gbps. The data rates for LAN range from 4 to 16 Mbps with the maximum of 100 Mbps.
Important Characteristics :
- Very high degree of interconnection between the computers
- High rate of data transmission.
- Physical connection of computers in a LAN is easy.
- Every computer in the LAN can communicate with any other computer.
- The medium used for data transmission is inexpensive.
LAN Topologies :
Here are few of the LAN topologies :
- BUS Topology
- Ring Topology
LAN Components :
Some of the important LAN components are as follows :
- File Servers
- Network Interfacing Unit
- Active and Passive Hubs
- LAN Cables or Communication Channels
Workstation refers to the individual,single computer. A communication capability is added enable it for networking.
File Servers :
File servers is a computer that allows the sharing of data, software and hardware resources by running special softwares.
It assists the transfer of data from one LAN to the other LAN.
Network Interfacing Unit ( NIU ) :
It is a unit which consists of hardware as well as software. It uses microprocessor to control the access and communication in a network.
LAN Cables or Communication Channel :
A cable is used for connecting the computers in a LAN. The communication from one computer to others takes place over the cables. So cables are called communication channels. The twisted pair,coaxial cables or optical fiber cables are used in LANs.
Advantages Of LAN
- High reliability. Failure of individual computer does not affect the entire LAN.
- It is possible to add a new computer easily.
- The transmission of data is at a very high rate.
- Sharing of peripherals devices such a printer is possible.
Disadvantages Of LAN
- If Sever develops a fault then users may not be able to run the application programs.
- A fault in the network can cause user to lose the data.
- It is difficult to make the system secure from hackers, novices or industrial espionage.
- Decisions on resource planning tend to become centralized.
- Networks that have grown with little thought can be inefficient in the long term.
- As traffic increases on a network the performance degrades unless it is designed properly.
- The larger the network becomes difficult to manage.
Applications of LAN
- File transfer ad file access
- Personal computing
- Office automation
- Distributed computing
- Word and text processing
- Document distribution
- Remote access to database
- Electronic message handling
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