In stop and wait protocol , every 4th packet is lost.Find number of packets ?

Question

In stop and wait protocol , every 4th packet is lost.If 8 packets are being sent, Find number of packets ?

Answer given is : 10

 

Shouldn't Acknowledgements considered as well , in such case answer should be 18 , Right ?

Comments

how many packets are being sent

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My bad , 8 packets are being sent ; edited.

Answer 1

Stop and Wait are easy to calculate- a resent happens only for the lost packet.

After 4 sends, we have a loss.

So, packet 4 lost, resent.

Packet 7 lost (since 4 was resent), resent.

So, totally 2 packets needs to be resent out of 8- 10 packets needs to be sent.

ACK won't be counted as packets as they are usually very very small.

Comments

I'm bit torn in accepting Acks are not data packets.Wiki mentions them as packets and it drives above question in more of ambiguous state.

https://en.wikipedia.org/wiki/Acknowledgement_(data_networks)

Answer 2

1 2 3 4 4 5 6 7 7 8   total 10 packet

Answer 3

We can always draw according the question and answer the related query.

Here it could be seen that every 4^th packet is lost so we marked it and re send .

Effectively we need to total 10 transmission for sending 8 packets.

(According to stop and wait protocol)

Answer 4

1 2 3 4 4 5 6 7 7 8

Total  of 10 packet sent. In given question , they ask every 4th packet is lost.