?PLEASE HELP ME WITH TCP TRANSMISSION PROBLEM. 3. (21 pts: 5 for a, 2 each for b

Question

?PLEASE HELP ME WITH TCP TRANSMISSION PROBLEM.

3. (21 pts: 5 for a, 2 each for b-i) We are using TCP Reno. ssthresh is set to 16. Assume no errors a. (5 pts) Starting from a window size of 1, calculate how many round you need to send 30 packets, as the window size (cwnd) grows each round. Subtract that from your remaining total to show how many packets remain in the last column Round # Packets Sent Packets Remaining 4 b. If you had 30 packets to send instead of 31, would anything change? Assume a packet is determined to be lost when cwnd-32 and ssthresh-16. Will ssthresh be changed? To what value? c. d. If you are in slow start, will cwnd pass through each integer value? In other words when we move in one round from cwnd-8 packets to the next round when cwnd-16, will cwnd jump to 16 or will it grow one by one? Why? When TCP sends an entire window's worth of many packets at a time, how many RTT's (round-trip times) is that considered to take? e. For the next questions, assume MSS is 1000 bytes, cwnd is 10,000 bytes f. How many packets can be sent in one window's worth of transmissions? g. When you are in slow start, and you receive an ACK, how much does cwnd grow? h. When you are in congestion avoidance, and you receive an ACK, by how much does each ACK cause the value of cwnd to increase? Assume MSS-1000 bytes cwnd-10,000 bytes, and show the equation and result.

Explanation / Answer

Solution:

a)

below is the table for how the cwnd will grow

#Round

Packets

#packets sent

packets remaining

1

1

1

30

2

2

3

28

3

3

6

25

4

4

10

21

5

5

15

16

b)

No, nothing will change

Explanation:

The packets sent value is reaching only 15 when we are sending 31 packets, there is no way it will reach the ssthreshold. So nothing will change.

c)

·         So if the packet is lost in case of TCP Reno, then there will be a timeout and slow start will happen after this so the value of cwnd will again be set to 1 or 2.

·         then again we will start to increase the size of the cwnd, by cwnd = cwnd + 1, at each recieved ACKs.

·         In this case the value of ssthresh will be changed and it will become Flight size/2.

·         Flight size=> The size of the data which was sent the last time when timeout happended.

d)

the value of cwnd will be growing one by one, this is how TCP Reno works. to avoid congestion.

e)

then expected RTT is 32 unit of time.

f)

The number of packets which can be sent in one window's worth of transmissions=

Since MSS is 1000 bytes, and each packet is of size 1000 bytes.

After getting the acknowledgment the cwnd size increases by 1 packet

which is going to be

1000 bytes.

g)

After getting the ACK the cwnd grow by one

and again we will start to increase the size of the cwnd, by cwnd = cwnd + 1, at each recieved ACKs.

please repost h part.

I hope this helps if you find any problem. Please comment below. Don't forget to give a thumbs up if you liked it. :)

#Round

Packets

#packets sent

packets remaining

1

1

1

30

2

2

3

28

3

3

6

25

4

4

10

21

5

5

15

16

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