3 Data Transmission

Question 1

3.1.6

Define protocol

Answer 1

A set of rules and procedures for exchanging data between computers.

Question 2

3.1.6

Define data packet

Answer 2

A data packet is one unit of data that computers use to send and receive messages or files over a network.

Question 3

3.1.6

What are the parts of a data packet?

Answer 3

Header:
* Receiver address: Identifies the packet destination
* Sender address: Identifies where the packet came from
* Protocol: Specifies the protocol to be used to handle the data packet
* Sequence number: The number specifies the order in which the packets should be reassembled.

Payload: The actual data being transported by the packet.

Trailer:
* Error-checking codes: Verifies the integrity of the data
* Transmission codes: To show whether the data packet is transmitted or re-transmitted

Question 4

3.1.7

List the essential functions of protocols

Answer 4

• Maintaining data integrity
• Manage flow control (managing the rate of data transmission, ensuring that the receiving device can process the data withotu being overwhelmed)
• Prevent deadlock (A deadlock is a situation where two sets of processes are blocked because they are waiting for each other to release a resource or perform an action)
• Manage congestion (congestion occurs when the data load on a network exceeds its data carrying capacity)
• Perform error checking (detect impairments introduced to data during transmission)

Question 5

3.1.8

Explain why the speed of data transmission across a network can vary

Answer 5

• Environmental interference (e.g. physical obstructions) typically affects data transmission speeds in wireless networks.
• Physical distance is a factor because it takes time for data to travel over a distance.
• Bandwidth limitations: Bandwidth refers to the maximum rate of data transfer across a network.
• Network congestion: Network congestion occurs when the amount of data moving through a network exceeds its capacity. When congestion occurs, it slows down the network because data packets have to wait for other data packets to be transmitted before them. Congestion may also cause packet loss.
• Configuration errors: Misconfiguration of network devices, such as routing tables or access control lists can disrupt network traffic and lead to slowdowns.

Question 6

3.1.9

Explain why compression of data is often necessary when transmitting across a network.

Answer 6

It is often necessary to reduce the amount of data being sent, thereby saving bandwidth and increasing transmission speeds. This can result in a more efficient use of network resources and significant cost savings.

Question 7

3.1.10

Outline the characteristics of metal conductor cables as transmission media

Answer 7

Reliability:
* highly reliable and have a long lifespan
* Less susceptible to interference compared to other transmission media

Cost: Relatively inexpensive
Security Less susceptible to eavesdropping and data interception compared to wireless transmission
Speed: Supports many transmission speeds

Question 8

3.1.10

Outline the characteristics of fibre optic cable as transmission media

Answer 8

Reliability: Highly reliable and not susceptible to many types of interference. Can also travel over long distances without signal loss.
Cost: It has high initial costs but typically requires less maintenance
Security: Highly secure because it is difficult to eavesdrop
Speed: Provides the extremely high bandwidth and data transmission speeds

Question 9

3.1.10

Outline the characteristics of wireless transmission media (typically radio waves)

Answer 9

Reliability: More susceptible to environmental interference and signal degration over physical distances
Cost: It can be cost effective as it eliminates the need for extensive cabling
Security: Depends on how robust the security measures are
Speed: Wireless networks are typically slower and have lower bandwidth than wireless networks. The signal speed also degrades with distance.

Question 10

3.1.11

Explain how data is transmitted through packet switching

Answer 10

Packet switching is when data is broken into data packets and then individually sent over the network and reassembled at the end.

1. The data is segmented into individual data packets.
2. The packets are routed into the network, and the routers decide how to forward the packet to its destination.
3. The packets travel across the network, possibly taking different routes to reach their destination.
4. The packets arrive at their destination and are reassembled in the correct order.
5. If the receiver detects that any data packets are corrupted or missing, it may send a request for retransmission to the sender. The sender, upon receiving the request, retransmits the missing packet.