課程影片與練習

課程簡介
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
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
1.29.Which of the following factors are usually included to calculate the delay (latency) of transmitting a packet from a source device (such as switch) to a destination device ?  
    下列哪些是計算從來源裝置(例如交換機)到目的裝置傳輸延遲時間的主要因素?
(a)Queuing time 排隊時間
(b)Transmission time 傳輸時間
(c)Propagation time 傳播時間
(d)Receiving time of the destination device 目的裝置的接收時間
(e)Table lookup time 查表時間

1.30.The “transmission time” of a network interface (card) to transmit a packet is defined as packet size/bandwidth. For a 1Mbps Ethernet interface, what is the transmission time to transmit a packet of size 1Kbytes ? 
     一個網路介面(卡)傳輸一個封包的“傳輸時間”是指將該封包大小除以網路卡頻寬。在1Mbps 乙太網路介面上傳輸一個大小為 1K 位元組的封包需多少時間??
(a)1 ms (毫秒)
(b)8 ms (毫秒)
(c)10 ms (毫秒)
(d)80 ms (毫秒)
(e)800 us (毫秒)

1.31.The “propagation time” of a link to transmit a bit from one end to another end is defined as link distance/speed of light. For a link of 30Km, what is the propagation time of such a link ? Assume the speed of light is 3 x 10^8 m/second.
     一個位元從鏈路的一端傳送到另外一端點的“傳播時間”是指該鏈路的距離/光速。若現有一鏈路長30公里,請問此鏈路的傳播時間為何 ? 假設光速是 3 x 10^8 公尺/秒。
(a)1 us (微秒)
(b)10 us (微秒)
(c)100 us (微秒)
(d)1 ms (毫秒)
(e)10 ms (毫秒)

1.32.Which of the following statements are correct for “transmission time” and “propagation time” ?   
     下列哪些對於”傳輸時間”與”傳播時間”的敘述是正確的?
(a)For short packet, the propagation time is more important as the packet will be complete transmitted quickly but needs a longer time to propagate to the other end of the link. 對短封包來說,傳播時間較為重要,因為短封包會很快傳送完成,但需要較長的時間來傳送到另一端。
(b)For short packet, the transmission time (bandwidth) is more important as the packet will be complete transmitted quickly and only needs a shorter time to propagate to the other end of the link. 對短封包來說,傳輸時間(頻寬)較為重要,因為短封包會很快傳送完成,而且需要較短的時間來傳送到另一端。
(c)For long packet, the propagation time is more important as the packet will be complete transmitted slowly but needs a longer time to propagate to the other end of the link. 對長封包來說,傳播時間較為重要,因為長封包會較慢完成傳送,但需要較長的時間來傳送到另一端。
(d)For long packet, the transmission time (bandwidth) is more important as the packet will be complete transmitted slowly but the first bit only needs a shorter time to propagate to the other end of the link. 對長封包來說,傳輸時間(頻寬)較為重要,因為長封包會較慢完成傳送,但第一個位元只需較短時間就可以傳播到另一端。
(e)The transmission time and propagation time are equal important for both short packet and long packet. 傳輸時間和傳播時間對於短封包和長封包同等重要。

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