Applied Test Series

Question

Let an IP datagram of the following data and header sizes be sent through a network of MTU 500 bytes. Calculate the fragment offset values that should be set for 3rd fragment ?

IP header = 40 bytes TCP header = 60 bytes•   Data = 1000 bytes•   MTU = 500 bytes•

Answer 1

IP datagram = 

1000

40

MTU = 500 Bytes

Therfore fragments are –

456

40

 

456

40

 

88

40

Fragment offset for 3^rd frame = 57 + 57

= 114 B

Comments

No need to consider TCP header ?

in such questions we only have to consider IP header ?

or we need to consider other headers also ..

please explain

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@casberg Fragmentation is done at Network layer so it can only see IP header while if we break the data at Transport layer it is known as segmentation.

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I got it buddy,

thanks

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Datagram length should be 

40B(IP Header) + [ 60B(TCP header) + 1000B(Data) ]

and 1060B will be fragmented.