Computer Networks and Topologies

This section explores the fundamentals of computer networks and topologies, covering essential concepts like LANs, WANs, client-server and peer-to-peer models, and common network hardware. Understanding the advantages and disadvantages of different topologies is vital for designing effective networks.

Networks

Advantages of Using Networks

• Resource Sharing: Devices, printers, and files can be shared among multiple users.
• Centralised Management: Centralised software updates, backups, and security management.
• Communication: Users can communicate easily through email, messaging, and collaborative tools.
• Flexibility: Users can log on to any computer on the network and access their files.

Disadvantages of Networks

• Security Risks: Networks are vulnerable to hacking, malware, and viruses, especially when connected to the internet.
• Complexity: Networks require management and configuration, which can be challenging and costly.
• Maintenance Costs: Network equipment, software updates, and management require ongoing investment.
• Dependence on Server: In a client-server network, if the server fails, it can disrupt access to resources.

Local Area Networks (LANs) and Wide Area Networks (WANs)

Local Area Network (LAN)

A network that covers a small geographical area, like a single building or campus.

Commonly used in schools, businesses, and homes.

Example: Office networks that connect computers, printers, and other devices within a building.

Wide Area Network (WAN)

A network that covers a large geographical area, connecting multiple LANs.

Usually connected through public networks like the internet.

Example: A company with offices in multiple cities connected through a WAN.

Factors That Affect Network Performance

Latency: The delay between sending and receiving data. High latency can cause lag and slow down data transfer, particularly in real-time applications.

Transmission Errors: Occur when data is corrupted or lost during transmission. Errors can lead to data retransmission, affecting network speed and performance.

Bandwidth: The maximum amount of data that can be transmitted over a network at one time. Higher bandwidth generally improves network speed and performance.

Client-Server and Peer-to-Peer Networks

Client-Server Networks

Central server manages resources, data, and applications.

Clients request services from the server (e.g., file access, printing).

Advantages: Centralised control, improved security, easier data backups.

Disadvantages: Server dependency, requires dedicated server hardware, and increased complexity.

Peer-to-Peer Networks

All devices (peers) share resources directly without a central server.

Suitable for small networks, like home or small office networks.

Advantages: Simple setup, no need for a central server, lower cost.

Disadvantages: Limited security, harder to manage, less efficient for large networks.

Local Area Network Hardware

Network Interface Controllers (NICs): Hardware that allows a device to connect to a network, either wired or wireless.

Transmission Media: Cables (e.g., Ethernet) or wireless signals that carry data across a network.

Network Connection Devices

Hubs: Basic devices that broadcast data to all devices on the network. Slower and less secure than switches.

Switches: Direct data to the specific device that needs it, improving efficiency and security.

Wireless Access Points (WAPs): Allow wireless devices to connect to a network, commonly used in Wi-Fi networks.

Routers: Direct data between different networks (e.g., LANs and the internet) and assign IP addresses within a network.

The Internet

Hosting: Storage of websites, applications, or data on remote servers, accessible over the internet. Companies may host their own websites or use third-party providers.

Domain Name Servers (DNS): Translate human-readable domain names (like www.example.com) into IP addresses. DNS servers help users find and connect to websites using easy-to-remember names.

The Cloud

Definition: Cloud computing stores data and applications on remote servers, accessed over the internet rather than locally.

Advantages: Accessible from any device with an internet connection, reduced hardware costs, automatic backups, and scalability.

Disadvantages: Dependence on internet connection, potential security risks, and subscription costs.

Star Networks

Star Topology

All devices are connected to a central hub or switch.

If one device fails, the network continues to function, but if the central hub fails, the whole network is affected.

Advantages of Star Topology

• Easy to add or remove devices without disrupting the network.
• Isolates device failure, ensuring other devices remain connected.
• High performance as each device has a dedicated connection to the central hub.

Disadvantages of Star Topology

• Dependent on the central hub; if it fails, the entire network goes down.
• Requires more cable than other topologies, increasing costs.

Star Topologies in Use: Commonly used in schools, offices, and home networks where devices are centrally connected for reliability.

Mesh Networks

Mesh Topology

Every device connects directly with multiple other devices, creating a "mesh" of interconnections.

Data can travel through multiple paths, making the network highly resilient to faults.

Advantages of Mesh Topology

• Highly reliable; if one connection fails, data can take another route.
• Better coverage in large areas, especially in wireless networks.

Disadvantages of Mesh Topology

• Expensive to set up due to the large number of connections required.
• Complex configuration and maintenance, especially for larger networks.

Mesh Topologies in Use: Commonly used in wireless networks, IoT systems, and military communications where reliability is crucial.