e-Consult | Revision Qns

1.

Describe the function of a router, a switch, and a hub in a network. Explain the key differences between these devices in terms of how they handle data transmission.

A router operates at the network layer (Layer 3) of the OSI model. Its primary function is to forward data packets between different networks. It examines the destination IP address of a packet and uses routing tables to determine the best path to forward the packet towards its destination. Routers are commonly used to connect networks like a home network to the internet, or to connect different subnets within a larger organization. They operate based on logical addresses (IP addresses).

A switch operates at the data link layer (Layer 2) of the OSI model. It connects devices within the same network (e.g., a home or office network). Switches learn the MAC addresses of devices connected to their ports and use this information to forward data frames only to the intended recipient. This targeted forwarding improves network efficiency by reducing unnecessary broadcast traffic. Switches operate based on physical (MAC) addresses.

A hub is a simpler device that also connects devices within a network. However, unlike a switch, a hub broadcasts any data it receives on one port to all other ports. This means that all devices connected to the hub receive the data, regardless of whether it's intended for them. This broadcast nature can lead to network congestion and security vulnerabilities. Hubs operate at the physical layer and are generally considered obsolete in modern networks due to their inefficiency.

Key Differences:

Layer of Operation: Routers (Layer 3), Switches (Layer 2), Hubs (Layer 1)

Addressing: Routers use IP addresses, Switches use MAC addresses, Hubs operate at the physical layer.

Data Forwarding: Routers forward packets between networks, Switches forward frames within a network, Hubs broadcast data to all ports.

Efficiency: Switches are more efficient than hubs due to targeted forwarding. Routers are efficient for inter-network communication. Hubs are the least efficient.

2.

Describe the key characteristics of fibre optic and wireless data transmission methods. In your answer, consider factors such as bandwidth, range, security, and susceptibility to interference.

Fibre Optic Transmission: Fibre optic transmission uses light to transmit data through thin strands of glass or plastic.

Bandwidth: Fibre optic cables offer exceptionally high bandwidth, significantly exceeding that of copper cables. This is due to the use of light and the ability to transmit more data per second.

Range: Fibre optic signals can travel over very long distances (tens or even hundreds of kilometers) with minimal signal degradation, making them ideal for long-haul communication.

Security: Fibre optic cables are inherently more secure than copper cables. It's extremely difficult to tap into a fibre optic cable without disrupting the signal, making eavesdropping challenging.

Interference: Fibre optic cables are immune to electromagnetic interference (EMI) and radio frequency interference (RFI), which can affect copper cables. This ensures a stable and reliable data transmission.

Cost: The initial cost of fibre optic cable installation can be higher than copper cabling. However, the long-term benefits often outweigh this.

Wireless Transmission: Wireless transmission uses radio waves, microwaves, or infrared signals to transmit data without physical cables.

Bandwidth: Bandwidth in wireless systems can vary greatly depending on the technology used (e.g., Wi-Fi, Bluetooth, cellular). Generally, bandwidth is lower than fibre optic.

Range: Range is limited by factors such as signal strength, obstacles (walls, buildings), and power constraints. Cellular networks have a wider range than Wi-Fi.

Security: Wireless networks are more vulnerable to security threats than fibre optic. Data can be intercepted if the network is not properly secured (e.g., using strong encryption).

Interference: Wireless signals are susceptible to interference from other devices operating on the same frequency, as well as from physical obstacles.

Mobility: A key advantage of wireless is mobility. Devices can connect to the network without being physically tethered to a cable.

In summary, fibre optic offers superior bandwidth, range, and security but can be more expensive to install. Wireless provides mobility and convenience but is generally less secure and more susceptible to interference.

3.

Question 3: Describe the differences between LAN, WAN, VPN and Mobile networks in a table format. Include details on typical speeds, geographical scope, security considerations, and common use cases.

Answer:

Network Type	Typical Speed	Geographical Scope	Security Considerations	Common Use Cases
LAN (Local Area Network)	10 Mbps - 10 Gbps	Limited (single building)	Physical security, access control, firewall	Home networks, office networks, school labs, resource sharing.
WAN (Wide Area Network)	1 Mbps - 1 Gbps (variable)	Large (countries, continents)	Encryption (VPN), firewalls, intrusion detection systems	Internet, corporate networks connecting multiple offices, cloud services.
VPN (Virtual Private Network)	Variable (dependent on underlying network)	Global (over public networks)	Encryption, authentication, secure tunneling	Secure remote access, bypassing geo-restrictions, protecting data on public Wi-Fi.
Mobile Network	2G - 5G (variable)	Variable (local to global)	Device security, network security, RF security	Smartphones, tablets, IoT devices, voice and data services.

14 Communications technology (3)