Networks use two main categories of transmission media to connect devices.

Guided (Wired) Media

Guided media transmit data through physical cables. The main types are:

Twisted Pair Cable — The most common Ethernet cable, consisting of copper wires twisted together to reduce electromagnetic interference. There are two variants:

• UTP (Unshielded Twisted Pair): Less expensive, used in most LAN installations. Common categories include Cat5 (up to 100 Mbps), Cat5e (up to 1 Gbps), and Cat6 (up to 10 Gbps).
• STP (Shielded Twisted Pair): Has additional shielding for better protection against interference, used in environments with high electrical noise.

Coaxial Cable — Has better shielding than twisted pair, traditionally used for cable television and some network installations. Standards include RG-58 (thin Ethernet) and RG-11 (thick Ethernet).

Fibre Optic Cable — Transmits data as light pulses through glass or plastic strands. Offers highest bandwidth and longest distances, immune to electromagnetic interference. Used for network backbones.

Unguided (Wireless) Media

Wireless media transmit data through electromagnetic waves without physical cables:

• Radio Waves: Used for Wi-Fi, Bluetooth, and cellular communications
• Microwaves: Point-to-point communication requiring line-of-sight
• Infrared: Short-range communication (TV remotes, Bluetooth)
• Satellite: Long-distance wireless communication

When creating a network, you need to understand the function of each device:

Cable Types for Ethernet

When connecting devices, you must choose the correct cable type:

Straight-Through Cable: Connects different device types. Both ends use the same wiring standard (T568-B). Used for:

• Computer to Switch
• Router to Switch
• Switch to Hub

Crossover Cable: Connects similar device types. One end uses T568-A, other uses T568-B. Used for:

• Computer to Computer
• Switch to Switch
• Router to Router

T568-B Wiring Standard (for Straight-Through)

Wi-Fi Standards

Components of a Wireless Network

• Wireless Access Point (WAP): Bridges wireless and wired networks
• Wireless NIC: Installed in computers for wireless connectivity
• SSID (Service Set Identifier): Network name for identification
• Security Protocols: WEP, WPA, WPA2, WPA3 for encryption

This practical example shows how to create a basic Ethernet network using Cisco Packet Tracer simulation software.

Step 1: Launch Packet Tracer and Add Devices

1. Open Cisco Packet Tracer application
2. From the device box, select "End Devices" and drag three PCs onto the workspace
3. Select "Switches" and drag one switch (e.g., 2960 or 2911) onto the workspace

Step 2: Connect Devices with Cables

1. Click the "Connections" icon (lightning bolt)
2. Select "Copper Straight-Through" cable
3. Click PC0 → choose FastEthernet → drag to Switch0 → choose an available port
4. Repeat for PC1 and PC2
5. Wait for link lights to turn green (Spanning Tree Protocol convergence)

Step 3: Assign IP Addresses

1. Click on PC0 → Desktop tab → IP Configuration
2. Enter IP Address: 192.168.1.2
3. Subnet Mask: 255.255.255.0
4. Repeat for PC1: 192.168.1.3, PC2: 192.168.1.4

Step 4: Test Connectivity

1. Click PC0 → Desktop tab → Command Prompt
2. Type: ping 192.168.1.3
3. A successful ping shows reply from destination

Example: Creating a Wireless Network

To add wireless capability to the network:

1. Add a "Wireless Access Point" from the wireless devices category
2. Connect the AP to the switch using a straight-through cable
3. Add a laptop with a wireless NIC
4. Configure the laptop to connect to the wireless network using the AP's SSID

When creating a network, consider these factors:

Functionality: The network must allow users to meet job requirements with reasonable speed and reliability.

Scalability: The design should accommodate growth without major changes.

Adaptability: Include no elements that limit future technology implementation.

Manageability: Design should facilitate monitoring and management.

Security: Implement appropriate access controls and encryption.

After creating your network, verify it works using these methods:

Ping Test: Uses ICMP to test connectivity between devices

• ping <IP_address> from Command Prompt

Verify Cable Continuity: Use cable testers to check for proper connections

Check Link Lights: Green lights indicate proper connection

Test Network Services: Verify file sharing, internet access, or printer sharing works

Suppose your school needs to create two networks: one for Administration (5 computers) and one for Computer Lab (20 computers). Given the network address 192.168.1.0/24:

Step 1: Determine subnet mask

• Need 2 subnets, borrow 1 bit: /25 (255.255.255.128)

Step 2: Calculate subnet ranges

Step 3: Assign addresses

• Admin network: 192.168.1.0/25 (supports 126 hosts, enough for 5)
• Lab network: 192.168.1.128/25 (supports 126 hosts, enough for 20)

In Tanzania, understanding how to create and manage networks is essential for many professions. For example, a small business owner in Dar es Salaam setting up a shop with multiple point-of-sale (POS) machines needs to create a local network using Ethernet switches and wireless access to connect all devices to the internet router. This allows inventory management software to sync sales data in real-time, enabling the owner to monitor daily transactions and stock levels from a central computer or mobile phone, improving efficiency and reducing losses from unrecorded sales.