What are the 7 layers of the OSI model and their functions? Discuss switches, Ethernet, parity check, network topologies, and IP addressing.

Here is the solution to question 4:

a)

i) The 7 layers of the OSI model in chronological order (from Application to Physical) are:

1. Application Layer
2. Presentation Layer
3. Session Layer
4. Transport Layer
5. Network Layer
6. Data Link Layer
7. Physical Layer

ii)

• Device applicable in Layer 2: Switch
• Network protocol applicable in Layer 2: Ethernet

b)

i) One method to detect errors during data transmission is Parity Check.
Parity check involves adding an extra bit (parity bit) to a block of data. This bit is set to either 0 or 1 to make the total number of 1s in the data block either even (even parity) or odd (odd parity). The receiver then checks the parity of the received data; if it doesn't match the agreed-upon parity, an error is detected.

ii) Two major considerations for selecting a topology for a school network are:

• Cost: The expense associated with cabling, network devices (switches, routers), and installation. Different topologies have varying hardware and cabling requirements.
• Reliability and Fault Tolerance: How resilient the network is to failures. Some topologies, like mesh, offer high redundancy, while others, like bus, are more vulnerable to single points of failure.

iii) Consider the internet protocol address 172.16.1.45

iv) Every IP address has two parts. For 172.16.1.45:

• Network ID: 172.16
• Host ID: 1.45

v) The class of the IP address 172.16.1.45 is Class B.

c)
Synchronous communication involves data transmission where both the sender and receiver are synchronized by a common clock signal. Data is sent in continuous blocks or frames, and timing is crucial for proper interpretation.
Asynchronous communication transmits data in discrete units, typically characters or bytes, with start and stop bits to frame each unit. There is no shared clock, and timing is managed by the individual data units themselves.

d)
Two guided transmission media:

• Twisted Pair Cable: Consists of pairs of insulated wires twisted together to reduce electromagnetic interference. It is commonly used in local area networks (LANs) for Ethernet connections.
• Fiber Optic Cable: Transmits data as pulses of light through thin strands of glass or plastic. It offers high bandwidth, long-distance transmission, and immunity to electromagnetic interference.

One unguided transmission medium:

• Radio Waves: Transmit data wirelessly through the air using electromagnetic waves. This medium is used in technologies like Wi-Fi, Bluetooth, and cellular networks for broadcasting and point-to-point communication.