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Visit the Go-Back-N Java applet at the companion Web site.

  1. Have the source send five packets, and then pause the animation before any of the five packets reach the destination. Then kill the first packet and resume the animation. Describe what happens.
  2. Repeat the experiment, but now let the first packet reach the destination and kill the first acknowledgment. Describe again what happens.
  3.  Finally, try sending six packets. What happens?
in Computer Networks by Boss (10.3k points) | 23 views

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1.ok first five packets will go then according to you first packet kill that means again you have to send five packets so here you have to send  total total 10 packets  because you send packet and it was kill so receiver always waiting for first packet so remaining packets will discarded.

2.if ack will loss of so avoid this you have to add some sequence number to avoid duplicate packets.

3.here first 10+1 packets to be send.

and after searching the new answer is

1.

Visit the Go-Back-N Java applet at the companion Web site.

  1. Have the source send five packets, and then pause the animation before any of the five packets reach the destination. Then kill the first packet and resume the animation. Describe what happens.

 

Since the first packet is killed, packets will be received out of order so they will be rejected at the receiver and once the timer goes out and the first packet is retransmitted then ACK is received. 

  1. Repeat the experiment, but now let the first packet reach the destination and kill the first acknowledgment. Describe again what happens.

In this case, since the first packet is successfully received, the receiver will accept other packets. However, once timer goes out if all other packets get acknowledged then as Gp Back N uses cumulative ACK, first will automatically get acknowledged. 

  1.  Finally, try sending six packets. What happens?

If the window size is greater than or equal to six, all six packets go through. However, if the window is five then it needs to wait for five packets before sending the sixth one.

 

Hope it is clear.

by (87 points)
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