Ace Test Series: Computer Networks - Tcp

Question

1st seq number is 1093,
2ns seq is 1094,
... 1460th seq number will be 2552. So the ack number sent by the reciever will be 2552+1=2553.

Is this right?

Answer in solution given is 2554.

Comments

Yes, 2553 looks correct.

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Answer in solution given is 2554.

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Any explanation given?

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This is their explaination:

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If initial seq no is 1 and 10B of data is sent then

total seq no consumed = (1 + 10) - 1 = 10

$\therefore$ Next seq no is 11

Similarlly,

total seq no consumed = (1093 + 1460) - 1 = 2552

$\therefore$ Next seq no is 2553

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Yup.

Same logic.

Thanks..

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It should be 1093+1460+1. Not 1093+1460-1

See sequence number definition here: http://www.rhyshaden.com/tcp.htm

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Seq number is say 0. And 1 byte is sent. Next sequence number that receiver will request will not be 0+1(size of pkt)+1.

Take small example and solve.

Answer 1

Answer is Next sequence number will be 2554. Because, receiver has received 2553 Bytes of data. Now it will request for the next byte i.e. 2554. So it will send 2554 as acknowledgement number.

Comments

seq number of the last bit that reciever will recieve will be 2552. According to my calculation.

Answer 2

I'll use following abbreviations :

ISN (initial sequence number)

SN (sequence number)

AN (acknowledgement number )

Solution :

ISN of sender = 1093 

ISN of Receiver = 391

To establish connection one sequence number for each of them would have been eaten up,  therefore 

next SN to be used for sender = 1094 and for receiver = 392

Now sender will send 1460 Bytes of data  with SN=1094 and AN = 392

Receiver will acknowledge the pkt with SN=392 and AN = 1094+1460 = 2554

Hence ack number sent by Receiver will be 2554.