Folks, there was some discussion after class today about the correctness of slides 49 and 53 (same picture). I said there may have been a mistake, but the slides are actually correct.
Here's what happens:
- When Alice receives Bob's ACK 500, she sets her window to 250 bytes. At that point she has already sent out 100 unacknowledged bytes (her SEQ 500), so she can send 150 more. She creates two segments: one with SEQ 600 (carries 100 bytes) and one with SEQ 700 (carries 50 bytes).
- When Alice receives Bob's ACK 600, she sets her window to 240 bytes. At that point she has already sent out 150 unacknowledged bytes (her SEQ 600 and her SEQ 700), so she can send 140 more. She creates two segments: one with SEQ 750 (carries 100 bytes), and one with SEQ 850 (carries 40 bytes).
