Packet & Circuit switching - internet structure 3

Question 1

What is circuit switching?

Answer 1

A method of communication where a direct link is created between two devices. The direct link is maintained for the duration of the entire conversation between devices. This process required two devices to transfer and receive data at the same rate.

• Provides the basis for traditional telephone networks
• Creates a temporary and dedicated link of fixed bandwidth between the source and destination that only lasts until the transmission is complete

Question 2

What is an advantage of circuit switching?

Answer 2

Guaranteed quality of transmission through dedicated bandwidth

• Excellent for data that needs constant link end-to-end, such as real-time video

Question 3

What is a disadvantage of circuit switching?

Answer 3

A lot of potential bandwidth can be wasted

Question 4

What is Packet Switching?

Answer 4

A method of communication in which data is communicated using packets across a network.

Breaks streams of data into smaller blocks, each sent independently of one another

Question 5

What are the Pros and Cons of Packet Switching?

Answer 5

At each node, packets are sent via whichever route the node decides is the least congested - this maximises bandwidth but doesn’t guarantee the quality of the transmission

Packets can take different routes to their destination and may arrive out of order

It is more affordable and efficient than circuit switching, as all bandwidth can be used at once.

Requires less complex infrastructure and can easily respond if parts of the network fail

Question 6

Compare Packet Switching and Circuit Switching

Answer 6

In CS, each data unit knows the entire path address which is provided by the source. In packet switching, each data unit just knows the final destination address intermediate path is decided by the routers. In packet switching, data is processed at all intermediate nodes, including the source system.

Question 7

Circuit switching vs Packet Switching

State their differences

Answer 7

CS:
- physical path between source and destination
- all packets use the same path
- reserves bandwidth in advance
- can cause a lot of bandwidth wastage
- no store and forward transmission

PS:
- no physical path
- packets travel interdependently
- does not reserve bandwidth
- supports store and forward transmission