Lesson Notes By Weeks and Term v3 - Senior Secondary 3
Networking
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Networking
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Subject: Computer & IT
Class: Senior Secondary 3
Term: 2nd Term
Week: 1
Theme: Information And Communications Technology
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Define networking List types of networks State types of network to pologies Draw flow diagram for each network to pology List network devices State the benefits of networking
Information And Communications Technology Networking Term: 2nd Term Week: 1 ---
1. Overview and Learning Objectives This topic introduces students to the fundamental concepts of computer networking, a critical component of modern information technology. Understanding networking is essential for students as they navigate an increasingly connected world, impacting communication, commerce, education, and entertainment in Nigeria. From accessing online learning platforms like NECO/WAEC portals to using mobile banking apps, or connecting computers in a cyber cafe, networking underpins nearly every digital interaction. This knowledge provides a foundational understanding for further studies in IT and prepares students for careers requiring digital literacy and network administration skills.
Learning Objectives: By the end of this lesson, students will be able to: Explain what computer networking means. Identify and differentiate between various categories of computer networks. Describe different ways computers can be physically arranged in a network (network topologies). Sketch visual representations (diagrams) of common network topologies. Name and explain the functions of different hardware components used to build a network. Enumerate the advantages and practical uses of connecting computers in a network.
Real-world Applications in Nigeria: Cyber Cafes: Students will understand how multiple computers in a cyber cafe are connected to share internet access and printers.
Schools and Offices: How computers in administrative blocks, staff rooms, or computer labs are linked for resource sharing and communication.
Banks and ATMs: The underlying network that allows customers to access their accounts from different branches or ATMs across the country.
Government Agencies: How different departments or ministries connect their systems for data sharing and service delivery.
Telecommunication Companies: The vast networks (WANs) that enable mobile communication and internet services across Nigeria.
2. Key Concepts and Explanations A. Definition of Networking Networking, in the context of computing, refers to the practice of linking two or more computing devices (such as computers, servers, printers, mobile phones, etc.) together to share resources, exchange data, and facilitate communication. These interconnected devices form a "network," allowing users to access shared files, printers, internet connections, and communicate electronically. The primary goal of networking is to enhance efficiency, collaboration, and resource utilization.
B. Benefits of Networking Networking offers several significant advantages:
1. Resource Sharing: Allows multiple users to share hardware resources (e.g., printers, scanners, hard drives) and software resources (e.g., applications, databases) from a central location, reducing costs and increasing efficiency. For example, in a school computer lab, one high-quality printer can serve all networked computers.
2. Data Sharing/Information Exchange: Enables users to easily share files, documents, and other information among connected devices. This facilitates collaboration and ensures everyone has access to the most current versions of data.
Example: Teachers sharing lesson notes or student records across departments.
3. Communication: Provides efficient means for communication between users through email, instant messaging, video conferencing, and collaborative platforms. This is vital for organizational efficiency.
4. Centralized Administration and Management: Networks allow for centralized control and management of resources, user accounts, security policies, and software updates, simplifying IT administration.
5. Cost-Effectiveness: By sharing hardware, software, and internet connections, organizations can significantly reduce their overall IT expenditure compared to purchasing individual resources for each user.
6. Enhanced Security: Centralized network management allows for better implementation of security measures like firewalls, antivirus software, and access controls to protect data.
7. Reliability and Backup: Data can be stored on central servers with robust backup systems, ensuring data integrity and availability even if individual workstations fail. C. Types of Networks Networks are typically categorized based on their geographical coverage.
1. Local Area Network (LAN): Definition: A network that connects computers and devices within a limited geographical area, such as a home, office building, school campus, or a group of adjacent buildings.
Characteristics: Typically uses Ethernet cables or Wi-Fi. Data transfer rates are high. Owned and managed by a single organization or individual. Nigerian
Example: The network connecting computers in a specific branch of Zenith Bank, a cyber cafe in Surulere, or the computer lab in a secondary school.
2. Metropolitan Area Network (MAN): * Definition: A network that spans a larger geographical area than a LAN but is smaller than a WAN, typically a limited geographical area, such as a home, office building, school campus, or a group of adjacent buildings.
Characteristics: Typically uses Ethernet cables or Wi-Fi. Data transfer rates are high. Owned and managed by a single organization or individual. Nigerian
Example: The network connecting computers in a specific branch of Zenith Bank, a cyber cafe in Surulere, or the computer lab in a secondary school.
2. Metropolitan Area Network (MAN): Definition: A network that spans a larger geographical area than a LAN but is smaller than a WAN, typically covering a city or a large campus.
Characteristics: Connects multiple LANs within a city. Often uses fiber optic cables. Data transfer rates are moderate to high. Can be owned by a single entity or a consortium. Nigerian
Example: A network connecting all the branches of a bank (e.g., First Bank) within Lagos metropolis, or the network connecting various government ministries within Abuja city center.
3. Wide Area Network (WAN): Definition: A network that extends over a large geographical distance, connecting LANs and MANs across cities, states, or even countries.
Characteristics: Uses public or private data transmission media, including telephone lines, fiber optic cables, satellite links, and cellular networks. Data transfer rates are generally lower than LANs. Often involves telecommunication providers. Nigerian
Example: The internet itself is the largest WAN. The network connecting all the branches of GTBank across Nigeria, or the network infrastructure used by MTN or Globacom to provide cellular and internet services nationwide. D. Types of Network Topologies Network topology refers to the physical or logical arrangement of connected devices (nodes) in a computer network. The physical topology describes the actual layout of cables and devices, while logical topology describes how data flows through the network. This lesson focuses on physical topologies.
1. Bus Topology: Description: All devices are connected to a single central cable, called the "backbone" or "bus." Data travels along this single cable in both directions, and each device checks if the data is intended for it. Terminators are used at both ends of the backbone to absorb signals and prevent reflections. Flow Diagram (Teacher should illustrate/guide students to draw): ``` [Terminator] -- [Computer A] -- [Computer B] -- [Computer C] -- [Computer D] -- [Terminator] | | | | (Cable/Backbone)--------------------------------- ``` Illustration Guide: Draw a straight horizontal line representing the backbone cable. Draw vertical lines connecting individual computers (nodes) to this backbone. Add "Terminator" at each end of the backbone.
Advantages: Inexpensive and easy to install for small networks. Requires less cable than other topologies.
Disadvantages: A break in the central cable brings down the entire network. Difficult to troubleshoot. Performance degrades with many devices. Not suitable for large networks.
2. Star Topology: Description: All devices are connected individually to a central hub, switch, or router. Each device has a dedicated cable segment connecting it to the central device. Flow Diagram (Teacher should illustrate/guide students to draw): ``` [Hub/Switch] / | \ / | \ [Computer A] [Computer B] [Computer C] | | | \---------|---------/ | [Computer D] ``` Illustration Guide: Draw a central circle or rectangle representing the hub/switch. Draw lines radiating outwards from the center, with a computer (node) at the end of each line.
Advantages: Easy to install and manage. If one cable fails, only that connected device is affected; the rest of the network remains operational. Easy to add or remove devices. High performance for smaller networks.
Disadvantages: Requires more cabling than bus topology. If the central device (hub/switch) fails, the entire network goes down. More expensive due to the central device.
3. Ring Topology: Description: Each device is connected to exactly two other devices, forming a circular pathway for data. Data travels in one direction around the ring, passing through each device until it reaches its destination. Flow Diagram (Teacher should illustrate/guide students to draw): ``` [Computer A] --- [Computer B] | | [Computer D] --- [Computer C] ``` Illustration Guide:* Draw devices (nodes) arranged in a circle. Connect each device to its immediate neighbours to form a closed loop. Add goes down. More expensive due to the central device.
3. Ring Topology: Description: Each device is connected to exactly two other devices, forming a circular pathway for data. Data travels in one direction around the ring, passing through each device until it reaches its destination. Flow Diagram (Teacher should illustrate/guide students to draw): ``` [Computer A] --- [Computer B] | | [Computer D] --- [Computer C] ``` Illustration Guide: Draw devices (nodes) arranged in a circle. Connect each device to its immediate neighbours to form a closed loop. Add arrows on the connecting lines to show unidirectional data flow.
Advantages: Data packets travel quickly with minimal collisions. Consistent performance under heavy network load.
Disadvantages: A break in any single cable or failure of a single device can disrupt the entire network. Adding or removing devices disrupts the network. Difficult to troubleshoot.
4. Mesh Topology: Description: Each device is connected directly to every other device in the network. This creates multiple paths for data transmission. Flow Diagram (Teacher should illustrate/guide students to draw): ``` [Computer A] --- [Computer B] | \ / | | \ / | [Computer D] --- [Computer C] ``` Illustration Guide: Draw devices (nodes). Connect every device to every other device with a direct line. For N devices, there are N(N-1)/2 connections.
Advantages: Highly fault-tolerant and reliable; if one path fails, data can be rerouted. Provides high security.
Disadvantages: Very expensive and complex to implement due to extensive cabling. Difficult to install and manage. Not practical for large networks.
5. Tree Topology (Hierarchical Topology): Description: A hybrid of bus and star topologies. Multiple star networks are connected to a central bus backbone. It's essentially a hierarchical structure where a central root node branches out to connect to lower-level nodes. Flow Diagram (Teacher should illustrate/guide students to draw): ``` [Main Server/Hub] | ----------------------- | | [Hub A] [Hub B] / | \ / | \ C1 C2 C3 C4 C5 C6 ``` Illustration Guide: Draw a main "root" hub/server. Branch out from this root to several secondary hubs (like a bus). From each secondary hub, draw lines connecting to individual computers (like a star).
Advantages: Offers good scalability. Point-to-point wiring to individual segments. Easier to manage and maintain large networks.
Disadvantages: If the main bus cable fails, the entire network fails. More complex to configure than a simple star or bus.
6. Hybrid Topology: Description: Any combination of two or more different topologies. For example, a star-bus topology where multiple star networks are connected via a bus backbone. Flow Diagram (Teacher should illustrate/guide students to draw): Illustration Guide: Combine elements from two or more basic topologies. For instance, draw two star networks, then connect the central hubs of these two star networks with a bus line.
Advantages: Highly flexible and scalable. Can be designed to optimize network performance and cost for specific needs.
Disadvantages: Can be very complex to design, install, and manage. More expensive due to the complexity. E. Network Devices These are hardware components used to connect computers and other devices to a network.
1. Network Interface Card (NIC) / Network Adapter: Function: A hardware component installed in a computer that allows it to connect to a network. It provides the physical connection to the network medium (e.g., Ethernet cable or Wi-Fi signal). Each NIC has a unique Media Access Control (MAC) address.
2. Hub: Function: A basic network device that connects multiple computers or other network devices. When a data packet arrives at one port, the hub simply broadcasts it to all other ports. It does not intelligently direct traffic.
Analogy: Imagine a busy market square where someone shouts a message, and everyone hears it, whether it's for them or not.
3. Switch: Function: An intelligent network device that connects multiple computers and network devices. Unlike a hub, a switch learns the MAC addresses of devices connected to its ports and forwards data packets only to the specific port where the destination device is located, improving efficiency and reducing network congestion.
Analogy: