Question 19 (Mandatory) (4 points)
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TCP congestion control example. Consider the figure below, where a TCP sender
sends 8 TCP segments at t = 1, 2, 3, 4, 5, 6, 7, 8. Suppose the initial value of the
sequence number is 0 and every segment sent to the receiver each contains 100
bytes. The delay between the sender and receiver is 5 time units, and so the first
segment arrives at the receiver at t = 6. The ACKs sent by the receiver at t = 6, 7, 8,
10, 11, 12 are shown. The TCP segments (if any) sent by the sender at t = 11, 13, 15,
16, 17, 18 are not shown. The segment sent at t=4 is lost, as is the ACK segment
sent at t=7
What does the sender do at t=17? You can assume for this question that no
timeouts have occurred.
Sets its cwnd window value to 1, and retransmit the segment with sequence
number 300
Cut its value of cwnd in half, and retransmit the segment with sequence number
300
Do nothing except increment the number of duplicate ACKS by 1.
Inform the upper layer that the connection is terminated, and close the socket.
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