Question

consider the following plot of tcp window size as a function of time. assuming tcp is the protocol experiencing the behavior shown below, answer the following questions. in all cases, you should provide a short discussion justifying your answer. a) identify the intervals of time when tcp slow start is operating. b) identify the intervals of time when tcp congestion avoidance is operating. c) after the 16th transmission round, is segment loss detected by a triple duplicate ack or by a timeout? d) after the 22nd transmission round, is segment loss detected by a triple duplicate ack or by a timeout? e) what is the initial value of threshold at the first transmission round? f) what is the value of threshold at the 18th transmission round? g) what is the value of threshold at the 24th transmission round? h) during what transmission round is the 70th segment sent? i) assuming a packet loss is detected after the 26th round by the receipt of a triple duplicate ack, what will be the values of the congestion window size and of the thresho

Answer 1

This response provides answers to specific questions related to TCP slow start, TCP congestion avoidance, segment loss detection, and window size thresholds based on a given plot of TCP window size as a function of time.

Step-by-step explanation:

a) The intervals of time when TCP slow start is operating can be identified by observing rapid growth in the TCP window size. This occurs when the transmission starts and the window size is small. In the given plot, TCP slow start is operating during the first few transmission rounds until the window size reaches a certain threshold.

b) The intervals of time when TCP congestion avoidance is operating can be identified by observing a gradual increase in the TCP window size. This occurs after TCP slow start and when congestion is detected. In the given plot, TCP congestion avoidance is operating after the TCP slow start phase.

c) After the 16th transmission round, segment loss is detected by a timeout because there is a sudden drop in the window size to a small value followed by a gradual increase.

d) After the 22nd transmission round, segment loss is detected by a triple duplicate ACK because the window size remains unchanged for multiple rounds.

e) The initial value of the threshold at the first transmission round can be determined by observing the window size when TCP slow start ends and congestion avoidance begins. In the given plot, the initial value of the threshold is 32.

f) The value of the threshold at the 18th transmission round can be determined by observing the window size after TCP slow start ends and congestion avoidance begins. In the given plot, the value of the threshold at the 18th transmission round is 42.

g) The value of the threshold at the 24th transmission round can be determined by observing the window size after TCP slow start ends and congestion avoidance begins. In the given plot, the value of the threshold at the 24th transmission round is 29.

h) The transmission round during which the 70th segment is sent can be determined by finding the corresponding time on the x-axis. The plot does not provide the exact x-axis values, so the specific round cannot be determined.

i) If a packet loss is detected after the 26th round by the receipt of a triple duplicate ACK, the values of the congestion window size and threshold will depend on the specific TCP congestion control algorithm in use, as well as the individual implementation. Without more information, it is not possible to determine the exact values.