LAN (Local Area Network) – Topology, Types, Applications, Advantages

Network which is devised to operate over a limited geographical area is referred as LAN or Local Area Network. This post will discuss in detail about what is LAN (Local Area Network), how it works, its topology, types, applications, advantages and disadvantages.

What is LAN (Local Area Network)

LAN is basically a Data Communication Network. In this type of Network, several computers and their peripherals like disc storage devices, printers are connected to a single high speed data line within a limited area. Local Area Network is usually a privately owned network. In LAN, data is divided and transmitted in the form of packets and regenerated back by the receiving computer.

Fig. 1 – Introduction to LAN

It provides high data rates extending from 10-100 Mbps and up. Latest LAN’s can provide data rate up to 10 Gbps. The coverage area is less than 10 kms. Like any other Networks, LAN also requires Hardware and Software components. Hardware consists of transmission medium and connecting devices like Transceivers, Bridges, Switches, Repeaters etc. Software has Application Programs which includes protocols defined by IEEE Standard. Fig. 2 shows schematic diagram of Ethernet LAN.

Fig. 2 – Schematic Diagram of Ethernet Local Area Network

Types of Local Area Network (LAN)

LAN’s can be implemented using:

• Ethernet LAN (Wired connection)
• WLAN (Wireless)

Ethernet LAN (Wired connection)

Ethernet LAN uses Ethernet cables to connect the devices in a network. In this type of connection, the network installation is wired and the Switches and Routers are configured using the network settings. Standard Internet Protocol is set, that allows the internet to run on different devices within the network.

Fig. 3 – Ethernet Local Area Network

WLAN (Wireless Local Area Network)

WLAN uses Radio waves as the means of communication. It does not require cables to connect the devices. The advantage of WLAN over LAN is the increased security it offers. The users can access the internet without wired connection (wireless) if they are within the range of the Router. With the help of WLAN connection, many devices can be connected simultaneously, provided they all are within the range of the Router.

Fig. 4 – Wireless Local Area Network (WLAN)

LAN (Local Area Network) Topology

Topology is defined as the pattern of interconnection between the nodes of the network. The three basic topologies of LAN are:

• Star Topology
• Ring Topology
• Bus Topology

Star Topology

In this network, all the nodes are connected to Central Node. The devices are not connected to each other and transmits the messages to the Central Node. The central node is responsible for transmitting the message to the required destination. It is the most widely used topology for LAN’s.

Ring Topology

In this network, the nodes are interconnected to make a closed loop. Each node communicates with the nodes on its either side with the help of Token (information passing). The nodes with Token are allowed to transmit data. This topology eliminates the connection of nodes with the central node i.e. there is no need of Network Server to control other devices.

Bus Topology

In this network, all the nodes including computers and servers are connected to a single cable termed as Bus. This network is easier compared to other networks and is economical. Source node transmits a signal which is broadcast to all the other nodes via Bus cable. Though the message is broadcast, the intended recipient receives the signal. The recipient can accept the signal if its MAC Address or IP Address matches and data transmission occurs in a single direction.

Fig. 5 – (a) Star Topology (b) Ring Topology (c) Bus Topology

How does LAN (Local Area Network) Work

To understand how LAN works, consider Fig. 6, which shows the 7- Layers of OSI Model. It is necessary to know the three lower levels of OSI Model i.e.

• Physical Layer
• Data Link Layer
• Network Layer

Fig. 6 – Seven Layers of OSI Model

Physical Layer

The Physical Layer transmits raw data bits over communication lines. It deals with establishing physical circuit between devices. Physical Layer protocols and standards are responsible for type of modulation to be used for transmitting digital data over analog transmission lines. It accounts for the components of network like Multiplexers, Repeaters, Modems etc.

Data Link Layer

The Data Link Layer is responsible for transferring data over the communication channel provided by the Physical Layer. This layer breaks the data into data frames, transmits the frames sequentially over the channel. Error detection and correction is done and the data is transmitted to Network Layer.

Network Layer

The Network Layer helps in routing the data across the network from source node to receiving node. This Layer provides interface between a host and the network. Based on Topology used, routing of packets takes place to the receiving device where the conversion of data occurs and the original data is obtained.

Read More About OSI Model, Characteristics of Seven Layers, Why to Use it & Limitations

Applications of LAN (Local Area Network)

The applications include:

• LAN is used for school environment, offices, hospitals etc as it allows sharing of resources like sharing data, scanners, printing and internet.
• LAN serves users at home to access internet.
• LAN’s are widely used in manufacturing industries where a central server coordinates the activities of other machines.
• High speed LANs are typically used to connect many slower networks together.

Advantages of LAN (Local Area Network)

The advantages of LAN are:

• Provides high-bandwidth communication.
• Transmission medium is inexpensive.
• Bandwidth is utilized effectively.
• Maintenance is easy.

Disadvantages of LAN (Local Area Network)

The disadvantages of LAN are:

• Speed reduces as it includes sharing of resources.
• Less Secure.
• Requires skilled technicians to setup the network.
• Covers Limited area.

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