Afzal Badshah, PhD

Introduction to Computer Networks

A computer network enables two or more computing devices to exchange data using hardware and software components. In today’s interconnected world, networks play a primary role in communication, data sharing, and access to information across various sectors such as education, healthcare, and finance. This tutorial introduces the fundamental building blocks of computer networks and explains how these elements work together to form an efficient data communication environment.

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What is a Computer Network

A network is a connection of two or more devices that work together to communicate, share information, and use resources with each other. For example, a network in our offices to share the printer or other computational resources.

What is the Internet?

A network of networks is called the Internet. It is the World Wide Web (www), which connects devices around the world.

Use of Computer Network

Use of Compute Networks

Computer networks serve various purposes and have numerous uses in today’s digital world. Here are some of the primary uses of computer networks:

Resource Sharing: Computer networks enable the sharing of hardware resources like printers, scanners, and storage devices. This makes it more efficient and cost-effective in a workplace or home environment

File Sharing: Networks allow users to share files and documents easily. This is especially crucial in collaborative work settings, where multiple users need access to the same files.

Communication: Computer networks support various forms of communication, including email, instant messaging, video conferencing, and VoIP (Voice over Internet Protocol). They facilitate real-time and remote communication across the globe.

Internet Access: Networks connect devices to the internet, providing access to a vast pool of information, online services, and entertainment. This is one of the most common uses of networks for individuals and businesses.

Data Backup and Recovery: Networks enable automated data backup, making it easier to recover data in case of hardware failures or disasters.

Remote Access: Networks allow remote access to computers and servers. This is valuable for IT professionals who need to manage systems from a distance.

Online Gaming: Multiplayer online gaming relies on networks to connect players from different locations, facilitating real-time gaming experiences.

E-commerce and Online Banking: Computer networks support online shopping and banking, allowing users to make secure transactions over the Internet.

Social Media: Social media platforms are accessible through networks, enabling users to connect, share updates, and interact with others.

Cloud Computing: Networks play a crucial role in accessing cloud-based services and storage, where data and applications are hosted on remote servers.

IoT (Internet of Things): IoT devices, such as smart thermostats, security cameras, and wearable tech, rely on networks to connect and share data for automation and monitoring.

Data Sharing in Research: Researchers use networks to collaborate and share data and findings with colleagues globally.

Business Operations: Networks are fundamental for business operations, supporting activities like inventory management, customer relationship management (CRM), and supply chain logistics.

Educational Institutions: Schools and universities use networks for online learning, student management systems, and research collaboration.

Healthcare: Networks are used for electronic health records (EHR), telemedicine, and remote monitoring of patients’ vital signs.

Government Services: Governments utilize networks for e-governance, public services, and secure communication among agencies.

These are just a few examples of the many ways computer networks impact our daily lives and various industries. They have become an integral part of modern society, driving connectivity, productivity, and innovation.

Network Topologies

Network topologies refer to the physical arrangement of devices (like computers and switches) in a network. The topology determines how information flows and the overall efficiency of the network. Here are some common topologies:

Bus Topology: Imagine a single cable running through all devices in a network. This is a bus topology. If one device fails, the entire network can be disrupted. It’s simple to set up but less reliable.

Bus topology

Ring Topology: In a ring topology, devices are connected in a circular fashion, forming a ring. Data flows in one direction around the ring. If one device fails, the entire network can be disrupted, but there are mechanisms to bypass faulty devices.

Ring topology

Star Topology: In a star topology, all devices are connected to a central hub or switch. This is like a star with the hub at the center. If one device fails, the rest can continue to operate. It’s more reliable than bus topology; however, it can be more expensive due to the central hub.

Star topology

Mesh Topology: In a mesh topology, every device is connected directly to every other device. This provides high redundancy and fault tolerance, however, it requires a large number of cables and can be complex to manage.

Ring topology
FeatureBus TopologyStar TopologyRing TopologyMesh Topology
StructureAll devices share a single backbone cableAll devices connect to a central hub/switchEach device connected in a closed loopEvery device connected to every other device
CostLow (less cabling required)Moderate to high (central device needed)Moderate (ring cabling)Very high (due to extensive cabling)
Ease of SetupEasy to installEasy to install and configureModerate complexityComplex to install and configure
Failure ImpactBackbone failure disables the networkHub failure affects entire networkOne failure can disrupt the loopHighly fault-tolerant (alternate paths exist)
PerformanceDegrades with heavy trafficHigh, as each device has a dedicated linkSlower, data must pass through intermediatesVery high, supports parallel transmission
TroubleshootingDifficult to identify faultsEasy due to central control pointDifficult to pinpoint issuesEasy (redundancy allows quick fault isolation)
ScalabilityDifficult to scaleEasy to add new devices via hubLimited; adding nodes requires rewiringNot scalable for large networks (cabling burden)

Classification of Networks

Networks can be classified into different types based on their size, geographical coverage, and purpose. Here are some common classifications of networks:

Personal Area Network

A small-scale network covering a short distance (a few meters to tens of meters) for connecting personal electronic devices.​

Characteristics of Personal Area Networks (PANs)

Local Area Network

Local Area Network (LAN) is a network of interconnected computers, devices, and peripherals within a limited geographic area, such as an office building, school, or home.​

Purpose: LANs are designed to facilitate data sharing, resource sharing, and communication among devices within the same physical location.​

Components: LANs typically consist of computers, servers, switches, and other network devices connected via Ethernet cables or wireless connections.​

Scope: LANs provide high-speed, low-latency communication, making them ideal for local, in-house or office operations.​

Characteristics of LAN​

Metropolitan Area Network (MAN)

Metropolitan Area Network (MAN) is a network that spans a larger geographic area than a local area network (LAN) but is smaller than a wide area network (WAN). It typically covers a city or a large campus.​

Characteristics of MAN

Wide Area Network

Wide Area Network (WAN) is a network that spans a large geographic area, often connecting multiple LANs, cities, or even countries.​

Purpose: WANs are designed to facilitate long-distance data communication and connect devices and LANs across vast geographical distances.​

Components: WANs use various technologies, including leased lines, fiber optics, satellite links, and the internet, to establish connectivity.​

Scope: WANs provide the infrastructure for global and intercontinental communication.​

Characteristics of Wide Area Networks (WANs)

FeaturePAN (Personal Area Network)LAN (Local Area Network)MAN (Metropolitan Area Network)WAN (Wide Area Network)
Full FormPersonal Area NetworkLocal Area NetworkMetropolitan Area NetworkWide Area Network
Coverage AreaVery small area (few meters)Small area (home, office, lab)Medium area (city, large campus)Very large area (multiple cities or countries)
OwnershipIndividualPrivate (individuals or organizations)Organization or ISPTypically public or ISP-controlled
SpeedModerate (Bluetooth, IR, USB)High (100 Mbps – 10 Gbps)Moderate to highVaries, generally lower than LAN/MAN
Setup CostVery lowLowModerateHigh
ExampleSmartphone to smartwatch connectionOffice/school computer networkCity-wide cable networks, metro Wi-FiInternet, multinational corporate networks
UsagePersonal device communication & syncFile/resource sharing in local setupsRegional service distribution, CCTV networksGlobal communication, large-scale data exchange

Complexity of Networks

Self Assessment

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