Question

Although new TCP implementations use the SACK option to report the out of order and duplicate range of bytes, explain how old implementations can indicate that the bytes in a received segment are out of order or duplicate.

Answer 1

Old TCP implementations indicate out of order or duplicate bytes using sequence numbers.

Step-by-step explanation:

Old TCP implementations can indicate that the bytes in a received segment are out of order or duplicate using sequence numbers. Each TCP segment contains a sequence number that indicates the position of the first data byte in that segment. If a TCP segment arrives out of order or is a duplicate, the sequence number will allow the receiver to identify this. For example, if the receiver receives a segment with a lower sequence number than the previous segment, it can infer that some segments were either lost or delivered out of order.