Data Communication and computer network

Data Communication

Data communication is the process of exchanging digital or analog data between two or more devices through a transmission medium such as wires, optical fiber, or wireless channels.

Computer Network

A computer network is a collection of interconnected computers and devices that share resources and information using communication channels.

📌Components of a Computer Network

• Sender (Transmitter)

• Receiver

• Transmission Medium

• Network Interface

• Protocols

Sender (Transmitter)

The device that sends data to another device.

Can be a computer, server, smartphone, or IoT device.

Receiver

The device that receives data from the sender.

Can also be computers, servers, or other network devices.

Transmission Medium

The physical path or wireless channel through which data travels.

Examples: twisted pair cables, coaxial cables, optical fiber, radio waves.

Network Interface

Hardware that connects a device to the network.

Examples: NIC (Network Interface Card), Wi-Fi adapter.

Protocols

Set of rules that govern data communication.

Ensure proper data formatting, error checking, and delivery.

Example: TCP/IP, HTTP, FTP.

📌Goals of Computer Networks

• Resource Sharing

• Communication

• Cost Efficiency

• Reliability

• Scalability

• Security

• Data Security & Integrity

Resource Sharing

• Goal: Allow multiple users or devices to share hardware (printers, storage), software, and data.

• Example: Multiple computers using the same printer or accessing a shared folder.

Communication

• Goal: Enable users and devices to exchange information efficiently.

• Example: Email, instant messaging, video calls.

Cost Efficiency

• Goal: Reduce overall costs by sharing resources instead of duplicating them.

• Example: One server serving hundreds of clients instead of each having separate storage.

Reliability

• Goal: Ensure the network works consistently and can recover from failures.

• Example: Redundant connections or backup servers to maintain uptime.

Scalability

• Goal: Network should easily expand to accommodate more devices or users.

• Example: Adding more computers or nodes without redesigning the whole network.

Security

• Goal: Protect the network from unauthorized access and cyber threats.

• Example: Firewalls, encryption, and secure passwords

Data Security & Integrity

• Goal: Ensure data is accurate, consistent, and protected from corruption or loss.

• Example: Checksums, digital signatures, and encrypted communication

📌Applications of Computer Network

• Email & Messaging

• File Sharing

• Remote Access

• Multimedia Streaming

• Cloud Computing

• IoT (Internet of Things)

• Online Gaming

• E-Learning & Online Collaboration

Email & Messaging

• Sending and receiving messages electronically.

• Example: Gmail, WhatsApp, Slack.

File Sharing

• Sharing files and resources between computers on a network.

• Example: Google Drive, Dropbox.

Remote Access

• Accessing systems or data from a distant location.

• Example: VPN, Remote Desktop.

Multimedia Streaming

• Real-time video, audio, and media delivery.

• Example: YouTube, Netflix, Spotify.

Cloud Computing

• Using networked servers to store, manage, and process data.

• Example: AWS, Google Cloud, Microsoft Azure

IoT (Internet of Things)

• Connecting devices to communicate and operate intelligently.

• Example: Smart homes, wearable devices.

Online Gaming

• Multiplayer games over the network with real-time interaction.

• Example: PUBG, Fortnite, Call of Duty.

E-Learning & Online Collaboration

• Learning and working remotely using networked systems.

• Example: Zoom classes, Google Classroom, Microsoft Teams.

📌 Types of Computer Network

• LAN (Local Area Network)

• MAN (Metropolitan Area Network)

• WAN (Wide Area Network)

• PAN (Personal Area Network)

• CAN (Campus/Corporate Area Network)

• SAN (Storage Area Network)

LAN (Local Area Network)

👉 A network within a small area like a building or office.
Example: Computers in a school lab connected via LAN.

MAN (Metropolitan Area Network)

👉 A network that covers a city or a large campus.
Example: Cable TV network in a city.

WAN (Wide Area Network)

👉 A network that spans large geographical areas or countries.
Example: The Internet is the biggest WAN.

PAN (Personal Area Network)

👉 A small network around a person’s devices within a few meters.
Example: Bluetooth between phone and headphones.

CAN (Campus/Corporate Area Network)

👉 A network that connects multiple buildings in a campus or company.
Example: University departments connected through CAN.

SAN (Storage Area Network)

👉 A high-speed network connecting servers to storage devices.
Example: Data centers using SAN for large storage.

📌 Types of Network Topologies

• Bus Topology

• Star Topology

• Ring Topology

• Mesh Topology

• Tree Topology

• Hybrid Topology

Bus Topology

👉 All devices are connected to a single central cable (bus).
Example: Early Ethernet networks.

Star Topology

👉 All devices are connected to a central hub/switch.
Example: Office LAN using a switch.

Ring Topology

👉 Devices are connected in a circular path; each device has two neighbors.
Example: Token Ring networks.

Mesh Topology

👉 Every device is connected to every other device directly.
Example: Military communication systems.

Tree Topology

👉 A combination of bus and star topology in a hierarchical form.
Example: University network with departments as branches.

Hybrid Topology

👉 A mix of two or more topologies for flexibility.
Example: Large organizations combining star and mesh.