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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?
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| (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 |
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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??
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| (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) |
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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。
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| (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) |
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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?
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| (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。 |