Computer Network Tutorial

Introduction of Computer Network Types of Computer Network Network Topology Computer Networking Architecture Transmission Modes (Data Flow) Basic Networking Devices Integrate Services Digital Network (ISDN)


OSI Model TCP/IP Model

Physical Layer

Digital Transmission Analog Transmission Transmission Media Switching

Data Link Layer

Error detection and Error correction Data Link Control Multiple Access Aloha

Network Layer

Network Layer - Logical Address Address Mapping Unicast Routing Protocol

Transport Layer

Process to Process Delivery User Datagram Protocol Transmission Control Protocol Stream Control Transmission Protocol Session Layer and Presentation Layer

Application Layer

Domain Name System Application Protocol E-mail Cryptography


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LAN Protocols in Computer Networks

A network of linked devices in a constrained physical space, such as a house, workplace, or college, is known as a Local Area Network, or LAN. These gadgets, which include printers, computers, and smartphones, may interact and share resources thanks to local area networks or LANs. Ethernet cables or wireless connections are commonly used in local area networks (LANs) to enable device communication.

LAN Protocols in Computer Networks

A Local Area Network (LAN) is primarily used to facilitate communication and data transfer between devices connected to the same network. This enables the devices to share resources, including files and printers, exchange information and communicate. Wide Area Networks (WANs) are more extensive networks made possible by the connections made between LANs. LANs are commonly used in private settings, including homes, businesses, and schools. They can be wired or wireless.

History of Local Area Network

Local Area Network (LAN) protocols have a long history, beginning with the earliest computer networking days. LANs are intended to link computers and other devices inside a constrained geographic space, like a university, business, or house. One of the main factors that have made it possible for linked devices to communicate and share data effectively is the development of LAN protocols.

Following are the significant events and creations in the development of LAN protocols:

  1. ALOHAnet (1970s):The University of Hawaii's ALOHAnet was regarded as one of the first wireless LAN deployments. Several devices shared the wireless medium using a simple contention-based protocol.
  2. Ethernet (1970s-1980s): Robert Metcalfe at Xerox PARC created one of the most critical LAN protocols. It functioned at 10 Mbps at first and used a coaxial cable as the transmission medium. Later advancements, including twisted-pair and fibre-optic cables, boosted its speed and efficiency.
  3. Token Ring (1980s):IBM launched Token Ring in the 1980s as an Ethernet substitute. Devices in token ring networks were arranged logically into rings, and a token-passing protocol was used to transfer data in an authorized way. Because of its complexity, although it offered deterministic access to the network, it was not as popular as Ethernet.
  4. ARCNET (1970s-1980s):Datapoint Corporation created the Attached Resource Computer NETwork (ARCNET). It was frequently used for industrial and control systems and employed a token-passing protocol akin to Token Ring.
  5. TCP/IP (1980s): Although TCP/IP is a suite of protocols for wide-area networking; its concepts were also used in local area networks (LANs). The current Internet was built on the TCP/IP suite, and Ethernet became the standard LAN technology, allowing LANs to be easily integrated into more extensive networks.
  6. Fast Ethernet (1990s): Developed at 100 Mbps, Fast Ethernet responded to the requirement for faster speeds. This enhancement enabled LANs to handle the growing bandwidth demand from data- and multimedia-intensive applications.
  7. Gigabit Ethernet (the 1990s-2000s): This technology enhanced speed to 1 Gbps, making it appropriate for high-demanding uses such as big file transfers and video streaming. It made use of fibre-optic and copper cables.

Architecture of Local Area Network (LAN)

A Local region Network, sometimes known as a LAN, is a type of network architecture that links devices in a specific geographic region, like a college, office building, or home. LANs are intended to make it easier for devices close to one another to communicate and share data. A thorough local area network (LAN) diagram can be made to provide a visual depiction of the connections and structure of the network. By effectively dividing network traffic, the local area network (LAN) VLAN configuration guarantees improved performance and focused security measures. A sample Local Area Network (LAN) diagram is shown in the image below.

Typically, a LAN's architecture consists of the following elements:

1. Network Devices

LANs are made up of various network devices to facilitate data transfer and communication. Among these gadgets are:

  • Switches: The main components of a LAN that link numerous devices together are switches. Based on the device's MAC addresses, they receive data packets and forward them to the desired location.
  • Routers: Data packets are forwarded by routers between several networks. Routers are used in local area networks (LANs) to link the LAN to other networks, such as the Internet.
  • Network Interface Cards (NICs): NICs are inserted in individual devices (such as printers and computers) to enable LAN connectivity. They allow data transmission and reception across networks between devices.

2. Network Topology

Different network topologies specify the network's logical or physical layout and can be applied to LANs. Typical LAN topologies consist of:

  • Bus Topology: In a bus topology, every device is linked to a bus, which is a single communication connection. Every device connected to the bus receives data sent by one machine. But only the data's intended recipient processes it.
  • Star Topology: Every device in a star topology is directly linked to a hub or central switch. Every device-to-device communication flow passes via the main controller. The network as a whole is unaffected if one device fails.
  • Ring Topology: A closed loop is formed when devices are connected in a circular pattern. Data moves around the ring from one device to the next until it arrives at its destination.
  • Mesh Topology: Every device in the network is connected to every other device in a mesh topology. This redundancy boosts reliability and fault tolerance by providing numerous pathways for data transmission.

3. Network Protocols

To provide guidelines and norms for communication, LANs use various network protocols. Among the popular LAN protocols are:

  • Ethernet: The most popular LAN protocol is Ethernet. It outlines the network's physical and data link layers and the addressing algorithms (MAC addresses), collision detection techniques, and data packet formats.
  • Wireless Local Area Network or Wi-Fi: Wi-Fi is a LAN protocol that allows devices to connect to the network wirelessly, eliminating the need for physical wires. It transmits and receives data wirelessly using wireless access points, often known as routers.
  • The protocols that control data transmission over LANs and the Internet are known as Transmission Control Protocol/Internet Protocol or TCP/IP. It offers a uniform data packet addressing, routing, and transmission structure.

4. Network Services and Apps

Local Area Networks (LANs) facilitate an array of services and applications that augment networks' functionality and user experience. These may consist of:

  • File Sharing and Network Storage: Local area networks (LANs) facilitate sharing of resources between devices, including printers and network-attached storage (NAS) units.
  • Network printing: LANs do away with the requirement for individual printers on each device
  • by allowing several devices to share a single printer.
  • Network Security: LANs are equipped with security features to safeguard data and stop illegal access. Firewalls, encryption, authentication systems, and access control are a few examples of this.
  • Network Management: To monitor and control network devices, diagnose network problems, and configure network settings, LANs frequently come with management tools and protocols
LAN Protocols in Computer Networks

Applications of Local Area Network

There are many different industries and organizations where Local Area Networks, or LANs, are used.

Following are among the most widely used LAN applications:

  • Sharing of files and printers: Local area networks (LANs) facilitate the sharing and access of resources between numerous users, including files and printers. Users can cooperate and work more productively as a result.
  • Gaming: You can play games with others across a network by connecting many gaming devices, like PCs and consoles, using LANs.
  • Communication: LANs can be used to help users communicate with each other via email, video conferencing, or instant messaging.
  • Data backup and storage: Local area networks (LANs) can be utilized for data backup and hold on a centralized server.
  • Remote access: Network resources, such as files and printers, can be accessed remotely from outside the network using LANs.
  • Business operations: Accounting, inventory control, and customer relationship management are just a few of the functions LANs frequently utilize in enterprises to support.
  • Education: LANs are used in colleges and universities to enable communication and teamwork and give lecturers and students access to resources like files and printers.
  • Healthcare: To maintain electronic medical data, communicate medical imaging, and improve communication between healthcare providers, LANs are utilized in healthcare organizations.

Working of Local Area Network

A LAN connects various devices, including servers, printers, and PCs, inside a constrained geographical area. The devices connect via a shared network channel, like Ethernet cables or Wi-Fi, to share resources and exchange data.

LAN operations are as follows:

  • Connection: Using Ethernet cables or Wi-Fi, the devices in a LAN are linked to a shared network medium, such as a switch or router.
  • Addressing: To identify a device on the network, each LAN member is given a distinct IP address.
  • Data transmission: A device divides up its data into little packets and sends them over the network to another device.
  • Routing: Using the IP address as the destination address, packets are routed across the network to the intended device.
  • Data reception: After obtaining the packets, the destination device returns the original data.
  • Data processing: The destination device analyses the data, carries out any required operations, and, if needed, produces a response.
  • Data transmission: The answer is sent back over the network to the original device using the same protocol as the first transmission.

Advantages of Local Area Network

  • Speed: Users may share big files and resources more quickly because of LANs' quick data transfer rates.
  • Resource sharing: By enabling users to share resources like storage devices, printers, and scanners, LANs can lower expenses while boosting productivity.
  • Centralized management: All devices on a LAN may be centrally managed and observed by IT administrators, which facilitates the maintenance of network security and problem-solving.
  • Easy to set up: Small to medium-sized enterprises often find LANs an affordable alternative because they are generally simple to set up and configure.
  • Enhanced cooperation: Local area networks (LANs) facilitate instantaneous communication and user collaboration, enhancing efficiency and group dynamics.
  • Reliability: LANs are less likely to experience disruptions from network congestion or other causes, so they are often more reliable than other networks.
  • Security: To safeguard confidential information and uphold network security, LANs can be set up with security features like firewalls, encryption, and access controls.

Disadvantages of Local Area Network

  • Limited geographic reach: LANs are usually restricted to a small region, like a single building or campus, so their applicability to businesses with several locations may be limited.
  • Security issues: Because local area networks (LANs) are interconnected, they are more susceptible to security risks like malware, hacking, and illegal access.
  • Scalability: A LAN may require more hardware and software as its size increases, making it harder to administer and maintain.
  • Cost: Establishing and keeping up a local area network (LAN) can be costly, especially if specialized hardware and software are needed.
  • Maintenance: A LAN needs regular maintenance, which can be expensive and time-consuming.
  • Interference: Slowdowns and other issues may result from other devices in the same physical area interfering with LAN connectivity.
  • Future Development and Improvement of Local Area Network: To satisfy the expanding needs of users, the local area network (LAN) protocol has experienced several innovations and improvements over the years. In the future, it will continue to evolve.

Future Development and Enhancement of Local Area Network

  • Security: LAN protocols must be improved to guarantee safe network connection. Improved intrusion detection and prevention systems, encryption, and authentication procedures are some examples of this.
  • Bandwidth: The need for bandwidth rises as more devices are connected to the network. LAN protocols that support high-speed data transfer rates must be developed to address this need.
  • Scalability: LAN protocols must be scalable to support the expansion of the network. This includes the capacity to add new devices without interfering with the current network's functioning and support for many devices.
  • Quality of Service: To guarantee that vital applications like VoIP, streaming media, and video conferencing are given precedence over less crucial traffic, LAN protocols must provide quality of service (QoS).
  • Management: Network monitoring, troubleshooting, reporting, and other capabilities are essential for manageable LAN protocols.
  • Integration with cloud-based services: LAN protocols must easily interface with cloud-based services to enable hybrid cloud settings as more companies shift their data and applications to the cloud.
  • IoT support: As more and more IoT devices are introduced to networks, particularly those with constrained memory and processing power, LAN protocols will need to accommodate them.


In conclusion, Ethernet is the leading technology for wired connectivity in LANs (Local Area Networks). We utilize switches, access points, and routers, among other network devices on our local area network (LAN). On our LAN, Ethernet is the most widely used standard; wireless devices utilize a different one.