CODEWITHSUNDEEP
network-programmingtcpnetwork-protocols
Shine Ten
Shine Ten

Reputation: 1

TCP sliding window problem about largest sequence number

If a sender sends a packet with sequence number 1000 and its window size has been constant at 20, what is the largest sequence number that the receiver has definitely received?()

The answer is 980.

How can I solve this problem? I think the the largest sequence number is 1000.

I'm going to cry.Thanks

Upvotes: 0

Views: 582

Answers (1)

Zac67
Zac67

Reputation: 2910

The sliding send window is the data "in flight" - it's been sent but not acknowledged yet. If the sender receives acknowledgement for the lowest sequence in the windows, the window advances and the next segment is sent.

Therefore, when the sequence 1000 has just been sent, the window contains sequences 981-1000. 980 is the highest sequence that has slid out of the window after acknowledgment.

Upvotes: 2

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