Consider an instance of TCP’s Additive Increase Multiplicative D...
The Answer is correct , but method of solving is wrong .
At
t=1, =>2mss
t=2, =>4mss
t=3, =>8mss
t=4, =>9mss (after threshold additive increase)
t=5, =>10mss (fails)
Threshold will be reduced by n/2 i.e. 10/2 = 5.
t=6, =>2mss
t=7 =>4mss
t=8, =>5mss
t=9, =>6mss
t=10, =>7mss.
So at the end of 10th transmission congestion window size will be 8 mss.
View all questions of this test
Consider an instance of TCP’s Additive Increase Multiplicative D...
Solution:
Given data:
- Window size at the start of the slow start phase = 2 MSS
- Threshold at the start of the first transmission = 8 MSS
- A timeout occurs during the fifth transmission
- We need to find the congestion window size at the end of the tenth transmission
AIMD algorithm is used to control the congestion window size. It follows the following steps:
1. Slow start phase: In this phase, the congestion window size is increased exponentially until it reaches a threshold value.
2. Congestion avoidance phase: In this phase, the congestion window size is increased linearly until congestion is detected.
Let's calculate the congestion window size at the end of each transmission:
- At the start of transmission 1, the congestion window size is 2 MSS.
- At the start of transmission 2, the congestion window size is 4 MSS (due to slow start phase).
- At the start of transmission 3, the congestion window size is 8 MSS (due to slow start phase).
- At the start of transmission 4, the congestion window size is 8 MSS (due to slow start phase).
- At the start of transmission 5, the congestion window size is 8 MSS (due to slow start phase).
- During transmission 5, a timeout occurs. This indicates congestion, and the algorithm enters the congestion avoidance phase.
- After the timeout, the congestion window size is set to the threshold value (8 MSS).
- At the start of transmission 6, the congestion window size is 8 MSS (due to congestion avoidance phase).
- At the start of transmission 7, the congestion window size is 9 MSS (due to congestion avoidance phase).
- At the start of transmission 8, the congestion window size is 10 MSS (due to congestion avoidance phase).
- At the start of transmission 9, the congestion window size is 11 MSS (due to congestion avoidance phase).
- At the start of transmission 10, the congestion window size is 12 MSS (due to congestion avoidance phase).
Therefore, the congestion window size at the end of the tenth transmission is 8 MSS (option A).
To make sure you are not studying endlessly, EduRev has designed Computer Science Engineering (CSE) study material, with Structured Courses, Videos, & Test Series. Plus get personalized analysis, doubt solving and improvement plans to achieve a great score in Computer Science Engineering (CSE).