11 / 14 IP & Addressing

Offset Three Seventy

A 4000 byte IPv4 datagram (20 byte header, no options, 3980 bytes of payload, Identification 0x2C1F) must cross a link with a 1500 byte MTU. The router fragments it into the smallest number of pieces. Each fragment carries its own 20 byte header.

Fragment Payload bytes Total Length MF Fragment Offset
1 1480 1500 1 0
2 1480 1500 1 185
3 ? ? ? ?

Fill in row 3.

A

1040 payload bytes, Total Length 1060, MF = 1, offset 371

B

1020 payload bytes, Total Length 1040, MF = 0, offset 370

C

1020 payload bytes, Total Length 1020, MF = 0, offset 370

D

1020 payload bytes, Total Length 1040, MF = 0, offset 2960