Question

Explain fragmentation as it relates to datagrams. Why is it necessary? How does IP keep
track of the fragments? Where does it occur? When and where are the fragments reassembled?
Give examples and be as specific as possible.

Answer 1

Fragmentation is the division of IP datagram into smaller parts so that they can pass through the transmission without any disruption , IP fragmentation is done when there is is limit on the maximum transmission unit and if the frame is greater than the MTU then fragmentation is done. it is necessary to keep the transmission uninterrupted during the whole process. We can keep the track of IP fragmentation by the identification field and the fragment offset where identification field is used to verify the frame number and the fragment offset is used to to verify the fragment number and place them in order. IP fragmentation occurs at the network layer of the sender and it is reassembled at the network layer of the receiver.