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4.18 Consider the procedure to maintain the spanning tree. For a bridge B with three ports x,y,z and root bridge ID = w, rpc = p. Assume port x is an R port, port y is a D port of a LAN1, port z is blocked and connected to a LAN2. Which of the following statements are correct for Bridge B ? 考慮維護擴張樹的過程。對於一個橋接器B，其上有三個埠，x,y,z，而其根橋接器辨識碼=w, 根路徑費用=p。假設埠x為一個R port，埠y為區域網路1的D port，埠z連接區域網路2且其目前在”blocking”狀態。下列哪些關於橋接器B的敘述是正確的? |
| The “hello” BPDUs will be received periodically only from port x. 只有埠x會週期性的收到“hello” BPDUs. | |
| The “hello” BPDUs will be received periodically from ports x and y. 埠x和埠y將會週期性的收到“hello” BPDUs. | |
| The “hello” BPDUs will be received periodically only from port z 只有埠z會週期性的收到“hello” BPDUs. | |
| The “hello” BPDUs will be received periodically from ports x and z. 埠x和埠z將會週期性的收到“hello” BPDUs. | |
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4.19 Consider the procedure to maintain the spanning tree. For a bridge B with three ports x,y,z and root bridge ID = w, rpc = p. Assume port x is an R port, port y is a D port of a LAN1, port z is blocked and connected to a LAN2. For bridge B, what actions will be taken if the hello BPDUs suppose to be received from port z are lost for a long time (a timeout event) ? 考慮維護擴張樹的過程。對於一個橋接器B，其上有三個埠，x,y,z，而其根橋接器辨識碼=w, 根路徑費用=p。假設埠x為一個R port，埠y為區域網路1的D port，埠z連接區域網路2且其目前在”blocking”狀態。當原本應該由埠z收到的hello BPDU遺失很長一段時間(逾時)時，橋接器B會採取什麼舉動? |
| Port z is selected as a new R port. 埠z 將會被選為新的R port. | |
| Port z is selected as a D port. 埠z 將會被選為新的D port. | |
| A BPDU with (with root bridge ID = w, rpc =p) is forwarded to port x 一個BPDU(根橋接器識別碼=w, 根路徑費用=p) 將會被轉送到埠x. | |
| A BPDU (with root bridge ID = w, rpc =p) is forwarded to port y. 一個BPDU (根橋接器識別碼=w, 根路徑費用=p) 將會被轉送到埠y. | |
| A BPDU (with root bridge ID = w, rpc =p) is forwarded to port z. 一個BPDU(根橋接器識別碼=w, 根路徑費用=p) 將會被轉送到埠z. | |
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4.20 Consider the procedure to maintain the spanning tree. For a bridge B with three ports x,y,z and root bridge ID = w, rpc = p. Assume port x is an R port, port y is a D port, port z is blocked and connected to a LAN m. For bridge B, what actions will be taken if the hello BPDUs suppose to be received from port x and port z are lost for a long time (a timeout event) ? 考慮維護擴張樹的過程。對於一個橋接器B，其上有三個埠，x,y,z，而其根橋接器辨識碼=w, 根路徑費用=p。假設埠x為一個R port，埠y為D port，埠z連接區域網路m且其目前在”blocking”狀態。當原本應該由埠x收到的hello BPDU遺失很長一段時間(逾時)時，且埠z也未收到hello BPDU，橋接器B會採取什麼舉動? |
| Bridge B will consider itself as a new root bridge and start the procedure to construct the spanning tree. 橋接器B 將會視自己為新的根橋接器並且開始進行建立擴張樹. | |
| port y is selected as a new R port. 埠y將會被選為新的R port. | |
| Ports x,y,z are selected as D port.埠 x,y,z 將會被選為D port. | |
| A BPDU with (with root bridge ID = B, rpc =0) is forwarded to ports x, y,z. 一個BPDU (根橋接器識別碼=B, 根路徑費用=0) 將會被轉送到埠x, y,z. | |
| A BPDU (with root bridge ID = w, rpc =q) is forwarded to port z. 一個BPDU (根橋接器識別碼=w, 根路徑費用=q) 將會被轉送到埠z. | |
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4.21 Consider the procedure to maintain the spanning tree. For a bridge B with three ports x,y,z and root bridge ID = w, rpc = p. Assume port x is an R port, port y is a D port, port z is blocked and connected to a LAN m. Which of the following statements are correct for the transmission of TCN (topology change notification) BDPU ? 考慮維護擴張樹的過程。對於一個橋接器B，其上有三個埠，x,y,z，而其根橋接器辨識碼=w, 根路徑費用=p。假設埠x為一個R port，埠y為D port，埠z連向區域網路m且其目前在”blocking”狀態。下列哪些關於傳輸 “拓樸架構變更(TCN)” BDPU 的敘述是正確的 ? |
| A TCN BPDU will be sent to port x if state of port z is changed to forwarding state. 如果埠z的狀態改為forwarding狀態時，一個TCN BPDU 將會被送到埠x. | |
| A TCN BPDU will be sent to port x if state of port y is changed to blocking state. 如果埠y的狀態改為blocking 狀態，則一個TCN BPDU將會被送到埠x. | |
| A TCN BPDU will be sent to port y if state of port z is changed to forwarding state. 如果埠z的狀態改為forwarding狀態，則一個TCN BPDU將會被送到埠y . | |
| A TCN BPDU will be sent to port z if state of port y is changed to blocked state. 如果埠y的狀態改為blocking狀態，則一個TCN BPDU將會被送到埠z. | |
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4.22 Consider the procedure to maintain the spanning tree of a BLAN. Which of the following statements are correct for the transmission of TCN (topology change notification) BDPU ?考慮維護擴張樹的過程。下列哪些關於傳輸 “拓樸架構變更(TCN)” BDPU 的敘述是正確的 ? |
| A bridge will send a TCN BDPU to the root bridge if one of its ports changed state (from blocking state to forwarding state, or vise versa) 一個橋接器的任何一個埠的狀態改變時 (由blocking狀態 轉為forwarding 狀態, 或反過來)，此橋接器會傳送一個TCN BDPU到根橋接器 | |
| The TCN BPDU will be delivered to the root bridge along the spanning tree. 此 TCN BPDU將會沿著擴張樹的路徑傳送到根橋接器. | |
| The TCN BPDU will be delivered to the root bridge along multiple communication paths. 此TCN BPDU將會沿著多條傳送路徑傳送到根橋接器. | |
| The TCN BPDU is delivered via a reliable, hop-by-hop method. 此TCN BPDU將會由橋接器以接力的方式可靠的傳送到根橋接器. | |
| The TCN BPDU is delivered via a best effort method. 此TCN BPDU將會以盡力方式傳送到根橋接器, 不保證根橋接器會收到. | |
