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Question

Consider a TCP message that contains 1024 bytes of data and 20 bytes of TCP header is passed to IP for delivery across two networks interconnected by a router (i.e., it travels from the source host to a router to the destination host). The first network has an MTU of 1024 bytes and the second has an MTU of 576 bytes. If all packets are correctly delivered, the number of bytes, including headers, are delivered to the IP layer at the destination for TCP message, in the best
case is _________ bytes. (Assume all IP headers are 20 bytes)

 

MY DOUBT IS IS INVOLVING 2 CASES:

1) DOES THE TCP WILL GENERATE SEGMENT  1024+20(HEADER). i.e. 1044 BYTE  SINGLE SEGMENT

                                                                              OR

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2)DOES THE TCP GENERATE 2 SEGMENT  FIRST ONE (984+20) SECOND ONE (40+20)

 

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P.S. "answer give is according to the 1044 single segment " . But as maximum tcp segment size we know at sender to be 1004(according to MTU=1024) then why have we considered a single segment of size 1044 size

Answer 1

Have a look to my solution 

Comments

Taking ip payload 1044B gives the correct result

but i am confused in 1 thing as host itself can do segmentation by knowing MTU of its own network so why did you considered tcp data(tcp payload +header)as 1044

 TCP should GENERATE 2 SEGMENTS FIRST ONE (984+20) SECOND ONE (40+20) by checking its MTU

and then forward it to network layer

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This is for visualization: