An IP packet with a payload size of 1200 bytes is fragmented into 3 equal sized
ID: 3707757 • Letter: A
Question
An IP packet with a payload size of 1200 bytes is fragmented into 3 equal sized fragments. Answer questions 12-15 corresponding to such a scenario. 12. The MF flag and "fragment offset" field for the first packet are O MF=1, offset=1 O MF=0, offset=0 O MF=1, offset=0 O MF=1, offset=8 13. The MF flag and "fragment offset" field for the second packet are O MF=1, offset=400 O MF=0, offset=50 O MF=1, offset=50 O MF=0, offset=400 14. The MF flag and "fragment offset" field for the third packet are O MF=1, offset=800 O MF=0, offset=100 O MF=1, offset=100 O MF=0, offset=1200 15. If the identity field in the original packet (before fragmentation) was X, then O The three fragments have identities X+1, X+2 and X+3 respectively O The three fragments have identities X+2,X+4,and X+6 respectively O The three fragments have identities X,X+8,and X+16 respectively O All three fragments have the same identity XExplanation / Answer
Question 12: (c) MF = 1, Offset = 0 ( First Packet )
Question 13: (a) MF = 1, Offset = 400 ( Second Packet )
Question 14: (a) MF = 1, Offset = 800 ( Third Packet )
Question 15: All three fragments have same identities X. ( To identify which packet this fragment belong to, the ID must be same for all fragments)
Please refer below packet structure for clear understanding of fragmented packets.
Frame 1 : payload 0-400 bytes (400 bytes)
Frame 2 : payload 401-800 bytes (400 bytes)
Frame 3 : payload 801-1200 bytes (400 bytes)
But in Question 13, the 3rd packet (supposed to be the last packet) should have the more fragments flag set to zero, because no more fragments present as it is the last fragment. But in the option, there is no such option MF = 0, Offset = 800. So I chose MF = 1, Offset = 800 considering it is expecting to send some more bytes(optional flags). But as frame 1 and frame 2 are expecting one frames to be sent after it, so MF will be set to 1 is those fragmented packets.