Network Protocols and Packet Switching: Question 2
Syllabus 14.2
A telecommunications company is training new engineers on the difference between circuit switching and packet switching, using four candidate descriptions.
Which one of these four statements correctly describes packet switching?
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Worked solution
Why B is correct
Packet switching divides a message into smaller, individually addressed units called packets. Each packet is forwarded independently by the routers it passes through, so packets belonging to the same message can travel via different routes and can arrive at different times, in a different order, from how they were sent. The destination device uses the packet numbers included with each packet to reassemble the original message correctly, whatever order the packets actually arrive in. This matches option B exactly.
Why the other options are wrong
- A describes a single path reserved for the whole communication, released only once it ends. This is the defining feature of circuit switching, not packet switching.
- C is incorrect: a router does not wait for an entire message to arrive before forwarding anything. It makes an independent forwarding decision for each packet as that packet arrives, without needing to know about, or wait for, any other packet from the same message.
- D is incorrect: packet switching does not guarantee packets follow the same route or arrive in order, quite the opposite. Different packets can take different routes, which is exactly why reassembly using packet numbers is needed at the destination.
Final answer
- B. Packet switching divides a message into separately addressed packets, which may travel by different routes and must be reassembled in the correct order at the destination.