Concepts and Protocols What is a Computer Network
A Computer Network is a collection of interconnected devices (computers, servers, routers, etc.) that communicate with each other to share resources, data, and services. Networks can range from small local area networks (LAN) to global networks like the Internet.
LAN (Local Area Network):
- Covers a small geographic area like a home, office, or campus.
- Used for connecting personal computers, printers, and other devices within the same location.
- Example:
- An office network connecting multiple computers to a shared printer.
- Spans a large geographic area, often connecting multiple LANs across cities, countries, or even continents.
- The Internet is the largest example of a WAN.
- Example:
- A multinational company’s network connecting its offices across the world.
- Covers a city or a large campus.
- Larger than a LAN but smaller than a WAN.
- Example:
- A university network connecting multiple campuses within a city.
- A small network typically used for connecting personal devices like smartphones, laptops, and Bluetooth devices.
- Example:
- A Bluetooth connection between a phone and a wireless headset.
Nodes:
- Devices like computers, printers, or servers that are part of the network.
- Physical or wireless connections between nodes, such as cables or Wi-Fi.
- Switches manage data traffic within a LAN.
- Routers direct data between different networks (e.g., from LAN to the Internet).
- Physical cables like fiber optics or copper wires, or wireless media like radio waves used for data transmission.
Key Network Protocols:
TCP/IP (Transmission Control Protocol / Internet Protocol):
- TCP ensures data is delivered reliably. It breaks down data into packets and ensures they are reassembled correctly at the destination.
- IP addresses and routes data to the correct destination.
- Example:
- When you send an email, TCP/IP ensures the message reaches the recipient.
- Protocol for transferring web pages on the Internet.
- Example:
- When you visit a website, HTTP handles the request and response between your browser and the web server.
- Used for transferring files between computers over a network.
- Example:
- Downloading a file from a server to your computer.
- Converts human-readable domain names (like www.example.com) into IP addresses, which computers can use to communicate.
- Example:
- When you type a website’s name in the browser, DNS resolves it to the corresponding IP address.
- Automatically assigns IP addresses to devices on a network.
- Example:
- When you connect your phone to Wi-Fi, DHCP assigns an IP address to your phone.
Network Topologies:
Bus Topology:
- All devices are connected to a single central cable (the bus).
- Example:
- An old-school network with a single cable running through a building.
- All devices are connected to a central hub or switch.
- Example:
- A modern office network with all computers connected to a central switch.
- Devices are connected in a circular fashion, and data travels in one direction.
- Example:
- A network where data travels around the ring until it reaches its destination.
- Devices are interconnected, allowing multiple paths for data transmission.
- Example:
- Highly redundant networks used by large organizations or data centers.
Importance of Computer Networks:
Resource Sharing:
- Devices and services (e.g., printers, files, internet) can be shared across a network, reducing costs.
- Enables communication via email, messaging, and voice calls across the globe.
- Provides access to vast information resources, such as web pages and databases.
- Networks allow centralized security measures (firewalls, VPNs) to protect data and monitor unauthorized activities.
Internet:
- The global network connecting millions of devices worldwide.
- Platforms like Facebook, Instagram, and Twitter rely on networks to allow users to communicate and share content.
- Enterprises use networks to connect offices, share documents, and run applications.