# Recent questions tagged congestion-control

1
Closed - Loop control mechanism try to : Remove congestion after it occurs Remove congestion after sometime Prevent congestion before it occurs Prevent congestion before sending packets
2
When we use slow-start algorithm, the size of the congestion window increases _______ until it reaches a threshold. Additively Multiplicatively Exponentially None of the options
1 vote
3
True or false? Consider congestion control in TCP. When the timer expires at the sender, the value of ssthresh is set to one half of its previous value.
1 vote
4
Suppose two TCP connections are present over some bottleneck link of rate R bps. Both connections have a huge file to send (in the same direction over the bottleneck link). The transmissions of the files start at the same time. What transmission rate would TCP like to give to each of the connections?
5
Suppose that the TCP congestion window is set to 18 KB and a timeout occurs. How big will the window be if the next four transmission bursts are all successful? Assume that the maximum segment size is 1 KB.
1 vote
6
Consider the effect of using slow start on a line with a 10-msec round-trip time and no congestion. The receive window is 24 KB and the maximum segment size is 2 KB. How long does it take before the first full window can be sent?
7
Some other policies for fairness in congestion control are Additive Increase Additive Decrease (AIAD), Multiplicative Increase Additive Decrease (MIAD), and Multiplicative Increase Multiplicative Decrease (MIMD). Discuss these three policies in terms of convergence and stability.
8
In Figure 6-20, suppose a new flow E is added that takes a path from R1 to R2 to R6. How does the max-min bandwidth allocation change for the five flows?
9
which value do we have to return when the question is like this ..what is the window size at the end of nth transmission? do we have to return window size at nth transmission or window size of (n+1)th transmission ...there always comes a single value gap which ... to be true in test series and sometimes false? pls clarify this ..don't want to loose marks if this comes in actual gate exam.
10
I thought 2600 cause after 34, it takes one RTT and size becomes 36 before sending the 14th segment(i.e., segment with window size = 36KB). Questions based on this are confusing. Please clarify.
1 vote
11
12
Consider a TCP connection using the multiplicative additive congestion control algorithm where the window size is 1 MSS and the threshold is 32 MSS. At the $8^{th}$ transmission timeout occurs and enters in the congestion detection phase. The value of the window size (in MSS) at the ... end of $12^{th}$ transmission. So we have to take the window size after the 12 RTTs right and not at 12th RTT?
1 vote
13
Consider an instance of TCP additive increase multiplicative decrease (AIMD) algorithm where the window size at the start of the slow start phase is 2 MSS and the threshold at the start of the first transmission is 12 MSS. Assume that a time out occurs during the ... ______. (in MSS) My question is, After reached to threshold, should we have to increase congestion window with 1MSS or with 2MSS.
14
here TOTAL 2000 segments need to be sent, and after x RTT, it will send 2001 segments but for total we shall take count of addition of all the previous also na?
1 vote
15
Please help, I am getting total number of transmission to get BACK TO 38 as 14 and NOT 15. after 14th, it would have became 38, so no need to consider 15th segment right?
1 vote
16
1 vote
17
Consider an instance of TCP's Additive Increase Multiplicative Decrease (AIMD) algorithm where the window size at the start of slow start phase is 2 MSS and the threshold at the start of 1 st transmission is 16 MSS. Assume TCP use over a lossy link i.e., timeout occur ... given window at the start of slow start phase is 2 MSS ;so when timeout occur should'nt we start with window size of 2 MSS]
18
Consider the following plot of TCP window size as a function of time. Assume TCP is operating with slow start, congestion avoidance, fast retransmit and fast recovery mechanism. What is the time interval where the slow start runs again because of a time-out ... cwnd to the value of threshold. It starts congestion avoidance phase again. Please explain in more details about the concept underlying?
1 vote
19
I am getting answer as 9, someone please post their solution stepwise, that would be of great help to identify the mistake.
1 vote
20
shouldn’t the ans be 5600? as it takes 14 RTTs to get back to full size ans given is considered 15 RTTs please confirm
21
Assume the scenario where size of the congestion window of a TCP connection be 40KB when timeout occurs. The MSS is 2KB. Propagation delay be 200msec. Time taken by TCP connection to get back to 40KB congestion window is …...
22
Consider an instance of TCP’s Additive Increase Multiplicative Decrease (AIMD) algorithm where the window size at the start of slow start phase is 1 MSS and the threshold at the start is 1st transmission is 16 MSS. Assume TCP use over a lossy link i.e., timeout occur after transmission of 7th packet . What is the congestion window size at the end of 14 RTT (in MSS)?
1 vote
23
Suppose you are using TCP to transfer a 4 MB file over a network. The receiver advertises a receive window of 4 MB. Assume that the retransmission timers expire after 5 RTTs. (a) If TCP sends 4KB segments, how many RTTs does it take to send the ... using implements fast retransmit and fast recovery. How many RTTs are saved by the fact that your TCP implements fast retransmit and fast recovery?
1 vote