Network or Computer Network
A computer network is a system where computers and other devices are connected so they can share data and work together.
Example: School Network
- Computers in a school are connected.
- Students can share files and use the same printer.
- Teachers can send assignments to all computers at once.
- This shows how devices work together in a network.
Main Components of a Network
- Nodes: Devices connected to the network, such as computers, smartphones, and printers.
- Links: The connections between devices. These can be wired (Ethernet cables) or wireless (Wi-Fi).
- Switches: Connects multiple devices in the same network to communicate efficiently.
How a Switch Works
- A switch works at Layer 2 (Data Link Layer) of the OSI model.
- It uses a hardware address called a MAC address.
- When a packet arrives, the switch reads the MAC address.
- It sends the packet only to the correct device, not to all devices.
Example: Using a Switch in an Office
Imagine you send a file to your colleague in another room.
- The file is broken into small parts called packets.
- Each packet has the address of your colleague’s computer (MAC address).
- The packets go to the switch.
- The switch checks the address and sends the packets only to your colleague’s computer.
- The computer puts all packets back together to form the original file.
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Routers
A router connects different networks and sends data from one network to another.
How a Router Works
Data travels in small parts called packets. Each packet contains the destination address. The router checks this address, chooses the best route, and forwards the packet to the right destination.
Example: Air Travel System
- Passengers are like data.
- They may travel in groups (packets).
- Each group has a ticket with the final destination (IP address).
- They may travel through different airports (routers).
- Finally, they reach the correct destination.
Objectives of Computer Networks
- Resource Sharing:
Networks allow devices to share resources like printers and storage.
Example: Many computers in an office can use one printer. - Data Communication:Networks allow people to send emails, messages, and make video calls.
Example: Employees can use Zoom or Microsoft Teams for meetings. - Connectivity and Collaboration:Networks connect devices so people can work together from different places.
Example: A team can work together on Google Drive at the same time.
Note:The Internet is the largest network in the world, connecting millions of networks globally.
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Fundamental Concepts in Data Communication
Data communication means sending data from one device to another.
Main components:
- Sender:The device that sends data (Example: a computer sending an email).
- Receiver: The device that receives data (example: a smartphone receiving the email)
- Message: Actual data being sent (Example: sending a text message, any video or any photo).
- Protocol: A protocol is a set of rules that devices follow to communicate with each other on a network. (Example: HTTP is a protocol used to load websites on the Internet.)
- Medium: Path through which data travels is called medium or communication medium or communication channel. It can be wired or wireless.
Networking Devices
Network devices are hardware devices that help connect computers and manage the flow of data in a network. They make sure devices can communicate with each other properly.
- Switch: Definition is already written above.
- Router: Definition is already written above.
- Hub: Connects multiple devices but sends data to all devices.
- Access Point (AP):An Access Point connects wireless devices to a wired network. It allows smartphones, laptops, and tablets to connect to the Internet wirelessly.
How an Access Point Works:
- It receives data from the wired network.
- Sends data wirelessly to devices like laptops, smartphones, tablets.
- Receives wireless data and sends it back to the wired network.
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Next Lecture # 2
15 Multiple Choice Questions (MCQs) on Computer Networks
Frequently Asked Questions (FAQs)
A computer network is a system where multiple devices are connected to share data and resources.
Nodes, links, switches, routers, and access points are the main components of a network.
A switch connects multiple devices in a network and forwards data to the correct device using MAC addresses.
A router connects different networks and directs data packets to the appropriate destination network.
An Access Point connects wireless devices to a wired network and enables Wi-Fi connectivity.
Data communication allows devices to send and receive information efficiently over a network.
A protocol is a set of rules that govern how data is transmitted and received across a network.
The medium is the physical or wireless path through which data travels, such as Ethernet cables or Wi-Fi.
The main objectives are resource sharing, data communication, and connectivity/collaboration.
The Internet is the largest network, connecting millions of smaller networks globally.