Question

consider the sender A transmits 12 data packet to B using stop wait protocol. if every 3rd packet is lost while transmission , then how many packets will the sender A has to send to B in total

Answer 1

Answer:

17

Explanation:

The stop an wait protocol has the sender window as well as receiver window size equal to 1.

It always retransmits the lost packet after time out.

There are 12 packets and every 3rd packet is being lost.

The explanation goes in the following way-

1 2 3 4 5 6 7 8 9 10 11 12(Initially)

     ^

1 2 3 3 4 5 6 7 8 9 10 11 12(Packet no. 3 retransmitted)  

               ^  

1 2 3 3 4 5 5 6 7 8 9 10 11 12(Packet no. 5 retransmitted)

                         ^      

1 2 3 3 4 5 5 6 7 7 8 9 10 11 12(Packet no. 7 retransmitted)

                                   ^

1 2 3 3 4 5 5 6 7 7 8 9 9 10 11 12(Packet no. 9 retransmitted)

                                              ^

1 2 3 3 4 5 5 6 7 7 8 9 9 10 11 11 12(Packet no. 11 retransmitted)

1 2 3 3 4 5 5 6 7 7 8 9 9 10 11 11 12(Result)

here 5 more packets need to be retransmitted namely 3,5,7,9,11

total no. of packets to be transmitted will be 12+5=17