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

4.4 Which of the following statements are correct?

下列有關橋接網路的敘述何者正確?

(a) To provide a reliable network connectivity, many physical loops may exist in a bridged LAN (BLAN). 為了提供網路穩定連結,橋接網路(BLAN) 拓樸可以存在一些迴圈.
(b) No physical loop is allowed in a bridge LAN. 橋接網路拓樸不允許存在迴圈.
(c) Before transmitting frames, the spanning tree of a BLAN should be constructed first. 在傳輸訊框以前,橋接網路的擴張樹必須先建立好.
(d) Based on the spanning tree structure, there is only one communication path between each pair of bridges. 根據擴張樹的結構,任兩個橋接器之間只會有一個傳輸路徑.
(e) For the spanning tree constructed by the IEEE 802.1D spanning tree algorithm, the communication path between each pair of bridges is optimized (shortest). 由IEEE 802.1D 擴張樹演算法所造出的擴張樹,任兩個橋接器之間的傳輸路徑一定最佳的 (最短的).

4.5 What may happen if loops exist in a bridged LAN and the spanning tree is not established ?

當橋接網路存在迴圈,且擴張樹尚未建立時,下列哪些狀況可能會發生?

(a) The receiver may receive duplicated frames. 接收者可能會重複收到訊框.
(b) The bridges may learn wrong ports for MAC addresses. 橋接器可能會將MAC位址對應的隸屬埠學習錯誤.
(c) The frames will be filtered by bridges correctly. 橋接器可以正確的過濾訊框.
(d) Each frame will be delivered to the destination via the shortest path between the source and destination stations. 每個訊框都可以經由傳送端與接收端之間最短路徑來傳送.

4.6 Which bridge in a bridged LAN will become the “root bridge” of the spanning tree ?

橋接網路中的哪個橋接器將會成為擴張樹中的根橋接器 (root bridge) ?

(a) The bridge is selected randomly 該橋接器是隨機選取的
(b) The bridge with the largest bridge ID 擁有最大識別碼的橋接器
(c) The bridge with the smallest bridge ID擁有最小識別碼的橋接器
(d) The bridge in the “center” of the bridged LAN 位於橋接網路最中心位置的橋接器

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