blade88
Junior Member level 2
Hello,
I solved an exercise regarding the TCP congestion control algorithm and I want your feedback
because I have a few questions.
The exercise says:
Given that MSS(Maximum Segment Size)=2KBytes and the Congestion Window at the time of a timeout is CongWin=36KBytes,
find CongWin after 5 ACKs.
My solution is the following:
At the time of the timeout, CongWin=36KBytes, so I set the variable threshold ssth=CongWin/2=18KBytes and Congwin is initialized in 1MSS.
From theory, when congwin becomes 18KBytes, I will move to the phase of congestion avoidance.
So, the slow start phase begins again:
After 1 ACK->Congwin=2MSS=2*2KB=4KB
After 2ACKs->Congwin=4MSS=4*2KB=8KB
After 3 ACKs-> Congwin=8MSS=8*2KB=16KB
After 4ACKs->Congwin=16MSS=32KB which is greater than ssth, so I enter the congestion avoidance phase, where Congwin increases linearly:
After 5Acks-> Congwin=17*MSS=34KB.
My question is should I enter the avoidance congestion phase when Congwin surpasses the threshold or when is it a little smaller than this?
My notes say that this happens when Congwin equals the threshold, but this is not the case here.
Thank you.
I solved an exercise regarding the TCP congestion control algorithm and I want your feedback
because I have a few questions.
The exercise says:
Given that MSS(Maximum Segment Size)=2KBytes and the Congestion Window at the time of a timeout is CongWin=36KBytes,
find CongWin after 5 ACKs.
My solution is the following:
At the time of the timeout, CongWin=36KBytes, so I set the variable threshold ssth=CongWin/2=18KBytes and Congwin is initialized in 1MSS.
From theory, when congwin becomes 18KBytes, I will move to the phase of congestion avoidance.
So, the slow start phase begins again:
After 1 ACK->Congwin=2MSS=2*2KB=4KB
After 2ACKs->Congwin=4MSS=4*2KB=8KB
After 3 ACKs-> Congwin=8MSS=8*2KB=16KB
After 4ACKs->Congwin=16MSS=32KB which is greater than ssth, so I enter the congestion avoidance phase, where Congwin increases linearly:
After 5Acks-> Congwin=17*MSS=34KB.
My question is should I enter the avoidance congestion phase when Congwin surpasses the threshold or when is it a little smaller than this?
My notes say that this happens when Congwin equals the threshold, but this is not the case here.
Thank you.