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6.14. In the sliding window protocol, the receiver maintains three variables: Receiving Window Size (RWS): Upper bound on the number of out-of-order frames that the receiver is willing to accept; Largest Acceptable Frame (LAF): Sequence number of the largest acceptable frame, and Last Frame Received (LFR): Sequence number of the last frame received.
Which of the following relationship is correct for these three variables ? 下列對於這三個變數的關係哪些是正確的 ? |
| (a) LAF –LFR > RWS | |
| (b) LAF – LFR ≤ RWS | |
| (c) LAF – RWS ≤ LFR | |
| (d) LFR + RWS ≤ LAF | |
| (e) LAF – RWS > LFR |
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6.15 Consider the three variables defined in question 6.14. Which of the following conditions are right timing for the receiver to slide its window ? 考慮在練習提 6.14 定義的三個變數. 下列哪個是接收端滑動視窗的正確時機 ? |
| (a) When a frame with sequence number within the sliding window is received 當收到一個訊框而其序號在滑動視窗內 | |
| (b) When a frame with sequence number of LFR+1 is received 當收到序號為 LFR+1 的訊框 | |
| (c) When a frame with sequence number of LFR +RWS - 1 is received 當接收到序號為 LFR +RWS – 1 的訊框 | |
| (d) When a frame with sequence number of LFR +RWS is received 當接收到序號為 LFR +RWS 的訊框 | |
| (e) When a frame with sequence number LFR +RWS +1 is received 當接收到序號為 LFR +RWS +1 的訊框 |
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6.16 Consider the three variables defined in question 6.14. When the receiver sliding its window, at most how many sequence numbers can be shifted by the window ? 考慮在練習提 6.14 定義的三個變數. 當接收端滑動其視窗時，最多可以移動多少個序號 ? |
| (a) 1 | |
| (b) 2 | |
| (c) RWS-1 | |
| (d) RWS | |
| (e) RWS+1 |
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6.17 Consider the three variables defined in question 6.14. Which of the following statements are correct when the receiver receives a frame with sequence number N ? |
| (a) The receiver will discard the frame if N ≤ LFR. 若 N ≤ LFR，接收端會丟棄此訊框. | |
| (b) The receiver will discard the frame if or N > LAF. 若 N > LAF，接收端會丟棄此訊框. | |
| (c) The receiver will accept the frame if N = LAF + 1 若 N = LAF + 1，接收端會接收此訊框. | |
| (d) The receiver will accept the frame if N = LFR 若 N = LFR，接收端會接受此訊框. | |
| (e) The receiver will accept the frame if LFR < N ≤ LAF 若 LFR < N ≤ LAF，接收端會接受此訊框 |
