A hospital connects the computers on a ward using wired connections.
Describe how using wired connections can reduce latency on this network.
Mark scheme
Award up to two marks for a linked description such as:
- Data travels along the cable directly to the switch on a single continuous path (1) so the time between sending and receiving the data is short (1)
- A cable is not affected by interference from other devices/wireless traffic nearby (1) so packets are not lost and resent, which would add to the delay (1)
- The switch sends the data only to the port of the correct device, not to every device (1) so the data spends less time travelling and the delay is lower (1)
- Fewer devices share a cable than share a wireless channel (1) so packets do not queue/wait before they are sent (1)
The first mark is for the way the wired connection carries the data; the second mark is for how this reduces the delay between sending and receiving.
Do not accept responses about bandwidth or the amount of data a cable can carry, as latency is the delay between sending and receiving.
Do not accept responses that confuse latency with speed/bandwidth, e.g. 'a wired connection is faster so there is less latency', unless they describe how the delay is reduced.
Do not accept answers that only say a wired connection is faster, with no link to the delay.
Example answers and how they were marked
The cable is not affected by interference from other devices (1) so packets do not need to be resent and the delay stays low (1).
Why: First mark for the cable being free of interference (1); linked development that no packets are resent and so the delay is lower (1).
There is no interference from other devices on a cable.
Why: Gives the first point of a linked pair (1) but does not say how this reduces the delay between sending and receiving.
Wired connections have a higher bandwidth so there is less latency.
Why: Confuses bandwidth with latency, which the 'Do not accept' lines rule out (0).