課程影片與練習
課程簡介
第1週：網路架構與七層參考模式簡介
第2週：IEEE 802.3 乙太網路 (Ethernet)
第3週：IEEE 802.11 無線區域網路 (Wireless LAN)
第4週：IEEE 802.1D 交換機的擴張樹演算法 (Spanning Tree Algorithm)
第5週：IEEE 802.1Q 虛擬區域網路 (Virtual LAN)
第6週：區域網路可靠傳輸技術 －－ 滑動視窗技術
※觀看影片請點擊影片名稱後方的"YOUTUBE"或"YOUKU"，
觀看YOUKU影片，請輸入密碼：mooc01004
第7週：路由器運作原理以及網路互連技術
第8週：TCP 與網路阻塞偵測與控制技術
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6.11 In the sliding window protocol, the sender assigns a sequence number (denoted as SeqNum) to each frame and also maintains three variables: Sending Window Size (SWS): Upper bound on the number of outstanding (unacknowledged) frames that the sender can transmit; Last Acknowledgement Received (LAR): Sequence number of the last acknowledgement received, and Last Frame Sent (LFS): Sequence number of the last frame sent.
在滑動視窗協議中, 傳送端會給每個訊框一個序號 (記為SeqNum)和維護三個變數: Sending Window Size (SWS): 傳送端可傳送不同訊框(未收到肯定回覆的訊框)數量的上限; Last Acknowledgement Received (LAR): 最後收到的肯定回覆序號， 以及 Last Frame Sent (LFS): 最後送出的訊框序號
Which of the following relationship is correct for these three variables ? 下列有關此三個變數的關係哪些是正確的 ?
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| (a) LFS – LAR ≤ SWS | |
| (b) LFS – LAR > SWS | |
| (c) LFS – SWS ≤ LAR | |
| (d) LAR + SWS ≤ LFS | |
| (e) LFS – SWS > LAR | |
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6.12 Consider the three variables defined in question 6.11. Which of the following conditions are right timing for the sender to slide its window ?
考慮在練習題 6.11 所定義的三個變數. 下列何者是傳送端滑動視窗正確的時機 ?
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| (a) When the acknowledgement of any frame within the sliding window is received 當接收到任何一個在滑動視窗內的訊框的肯定回覆 | |
| (b) When the acknowledgement of LAR+1 is received 當接收到序號為 LAR+1 的訊框的肯定回覆 | |
| (c) When the acknowledgement of LAR+SWS is received 當接收到序號為 LAR+SWS 的訊框的肯定回覆 | |
| (d) When the acknowledgement of LAR+2 is received 當接收到序號為 LAR+2 的訊框的肯定回覆 | |
| (e) When the acknowledgement of LAR+SWS-1 is received 當接收到序號為 LAR+SWS-1 的訊框的肯定回覆 | |
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6.13 Consider the three variables defined in question 6.11. When the sender sliding its window, at most how many sequence numbers can be shifted by the window ?
考慮在練習題 6.11 定義的三個變數. 當傳送端滑動視窗時, 最多可以移動多少個序號 ?
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| (a) 1 | |
| (b) 2 | |
| (c) SWS | |
| (d) SWS-1 | |
| (e) SWS+1 | |
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