CN:Transport Layer: Data Transfer

Question

What should be the value of Y, when P has no data to send to Q?

Comments

@akb

this seems correct! but what does this mean that server is sending back the same data to client? what is title of this diagram? can you post the whole page please here, please?

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It is from kurose and ross book page number 237

link of this book

http://web.csulb.edu/~rlaster/docs/cecs572.pdf

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Many thanks @akb!

Answer 1

Here we know that : 

TCP is full duplex as far as data communication is concerned . Also acknowledgement is piggy-backed here i.e. acknowledgement along its own data is sent by the receiver to sender and vice versa in their own turns.

So

a) Sender sends data with sequence numbers (0 - 99) to receiver at the first step.

b) Receiver is free to send data beginning with other sequence number so sends data from sequence number (200-299)..And it sends the acknowledgement as well with the acknowledgement number as indicated by the next byte sequence number it is expecting from sender which is 100 in this case.So X = 100

c) So sequence number in the next round by the sender will be (100) i.e. sender will start transmitting from sequence number 100.At the same time it acknowledges receiver data and hence sends next expected byte sequence no from receiver which is 300 in this case.So Y = 100 , Z = 300

From "Computer Networking A Top Down Approcah by Kruose"

Hence D) should be correct option.

Comments

Habib, please note that P has nothing to send to Q, then what will be the sequence used by P?

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@Habib for your reference:

From Forozuan, see the last transition, if the sequence number used by client is 10001 it means, client is sending 1 byte to server.

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I would say there are some mistakes which are in "Forouzan" , possibly printing mistake etc.. Wht is the point of sending same data again when u have transmitted it to receiver successfully.

Till now wht I have learnt will not change by a single misprint in the book . I hope u get my point @manu00x..

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@Habib can you post a screenshot here?

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I think I have explained every aspect wht is required in this question in my answer itself. Okay I will attach that soon as well

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@habib whatever you explained if it is true :) then definitely same should be in some book?

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Keep on doubting . Same u can verify from previous year's questions also.

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ok, link of any previous year questions?

Answer 2

option D

Comments

This is a place of systematic discussion @1gate_cracker..Not the platform for playing KBC by reporting just option a) ,b) etc..I hope my message is clear to you @1gate_cracker..:)