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+22 votes
2k views

Which of the following statements are TRUE?

  • S1:  TCP handles both congestion and flow control
  • S2:  UDP handles congestion but not flow control
  • S3:  Fast retransmit deals with congestion but not flow control
  • S4:  Slow start mechanism deals with both congestion and flow control
  1. $S1$, $S2$ and $S3$ only
  2. $S1$ and $S3$only
  3. $S3$and $S4$ only
  4. $S1$, $S3$ and $S4$ only
asked in Computer Networks by Boss (19.1k points)
edited by | 2k views
–2
s2 and s4 are only correct
0
s3 is also correct because in slow start we consider both the receiver window size and congestion window size. so it takes care of both flow control and congestion control
0
see the gate ques...explaination in ans
–1
you are correct . ss deals with congestion control only
+1
Imp point -> Slow start is way Sender tries to gauge network capacity.

2 Answers

+40 votes
Best answer

(S1)  TCP handles both congestion and flow control $\Rightarrow$ True.
 IT uses congestion window for congestion control & Advertisement window for flow control
(S2)  UDP handles congestion but not flow control $\Rightarrow$ UDP does not handle
congestion but also not handle flow control.
(S3)  Fast retransmit deals with congestion but not flow control$\Rightarrow$ Yes.
Fast Retransmit is technique for detecting out of Order Datagram & Sending it.
It is congestion control technique and has no relation with Flow control
(S4)  Slow start mechanism deals with both congestion and flow control $\Rightarrow$ False.
It has nothing to do with Flow control. Flow control is taken care by Advertisement window.
Slow start is way Sender tries to gauge network capacity !

Answers : S1 and S3 only.

answered by Boss (42.8k points)
edited by
+2

Excellent explanation.yes

+1
Flow control also uses fast tramsmission rule.

Even if we are not apllying congestion policies say rcvd<cwd,in this case also if some frame's ack is lost then also tcp transmits after 3 dup acks,please check and tell.
0
can somebody expalain s3 statment in detail
0

@ Moin Mukhtar

In fast retransmit whenever the sender gets 3 ack of same sequence number it can safely assume that that packet has been lost and it retransmits the packet without waiting for the time out.

+12 votes

Tcp handles both Congestion Control and Flow Control. For Flow Control it uses Sliding Window Protocol Algorithms and for Congestion Control it uses four congestion control algorithms: slow start, congestion avoidance, fast re-transmit, and fast recovery.

So Option (B)

answered by Active (3.8k points)
0
Yes, and UDP has no congestion avoidance whatsoever!

So, option B.
0
I think option should be D. Because Slow start also considers receiver window size.
0
B should be the answer
0
Can you explain what is fast recovery?

@Danish
Answer:

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