Discovery 17: Configure and Verify EtherChannel探索活動 17：設定並驗證 EtherChannel

Start by accessing the console of SW1 and displaying the interface status summary on SW1.

首先存取 SW1 的主控台，並顯示 SW1 的介面狀態摘要。

On SW1, enter the following command:

在 SW1 上，輸入以下指令：

Ethernet0/2 and Ethernet 0/3, which are connected to SW3 are trunk interfaces. Trunking is configured with the native VLAN set to VLAN 99.

連接到 SW3 的 Ethernet0/2 與 Ethernet 0/3 是中繼介面。中繼已設定，原生 VLAN 設為 VLAN 99。

Ethernet1/0 is an access interface, assigned to VLAN 10.

Ethernet1/0 是存取介面，指派給 VLAN 10。

Ethernet 0/0 and Ethernet 0/1 are also trunk interfaces. They are connected to SW4 switch, and configured with the native VLAN set to VLAN 99.

Ethernet 0/0 與 Ethernet 0/1 也是中繼介面。它們連接到 SW4 交換器，並設定原生 VLAN 為 VLAN 99。

Interfaces Ethernet 1/1, Ethernet 1/2, and Ethernet 1/3 are not in use and are disabled.

介面 Ethernet 1/1、Ethernet 1/2 與 Ethernet 1/3 未被使用，且已停用。

Examine the topology. Switches are interconnected with multiple trunk connections. There are many physical loops in the topology. To understand what the topology is, after the STP performs its processing, you need to examine the STP information on the switches. You need to establish what the resulting topology is for each VLAN after STP calculations. To begin, display the spanning tree information for VLAN 10 on SW1. To view STP information, use the show spanning-tree command. To view STP information for a specific VLAN, use the show spanning-tree vlan vlan-id command with the appropriate VLAN identifier. Display the spanning tree information for VLAN 10 on the other switches to complete your understanding of the VLAN 10 topology. Then examine the STP configuration for VLANs 20 and 1, to determine the STP topology for these VLANs.

檢視拓樸。交換器之間以多條中繼連線互連，拓樸中存在許多實體迴圈。為了瞭解 STP 處理完成後的實際拓樸，你需要檢視各交換器上的 STP 資訊，並判斷每個 VLAN 在 STP 計算後的結果拓樸。首先，在 SW1 上顯示 VLAN 10 的生成樹資訊。若要檢視 STP 資訊，可使用 show spanning-tree 指令；若要檢視特定 VLAN 的 STP 資訊，可使用 show spanning-tree vlan vlan-id 指令並指定對應的 VLAN 識別碼。請在其他交換器上顯示 VLAN 10 的生成樹資訊，以完整瞭解 VLAN 10 的拓樸。接著檢視 VLAN 20 與 VLAN 1 的 STP 設定，判斷這些 VLAN 的 STP 拓樸。

On SW1, enter the following command:

在 SW1 上，輸入以下指令：

The output you are seeing displays STP-related information for VLAN 10. The VLAN0010 "title" indicates that you are seeing STP information only for VLAN 10, which is named VLAN0010.

你看到的輸出顯示 VLAN 10 的 STP 相關資訊。VLAN0010「標題」表示你所看到的是僅限 VLAN 10 的 STP 資訊，該 VLAN 名稱為 VLAN0010。

The first part of the output provides two blocks of similar information. The first block gives information about the root switch and the second block gives information about the switch you are administering. The STP information for the root switch provides the STP priority and MAC address, the STP cost to the root switch, root port identifier (on your switch), and the STP timers. When the switch you are administering is the root switch, in place of the cost and port identifier, you will see the phrase This bridge is the root. As you can see from the output, SW1 is not the root switch.

輸出的第一部分提供兩組類似的資訊。第一組提供根交換器的資訊，第二組提供你正在管理的交換器的資訊。根交換器的 STP 資訊包含 STP 優先權與 MAC 位址、到根交換器的 STP 成本、根埠識別碼（在你的交換器上），以及 STP 計時器。當你正在管理的交換器就是根交換器時，成本與埠識別碼的位置會顯示「本橋接器即為根」字樣。從輸出可以看出，SW1 並非根交換器。

The second block of information provides STP priority and MAC address, STP timers, and aging time for the switch you are administering.

第二組資訊提供你正在管理的交換器的 STP 優先權與 MAC 位址、STP 計時器，以及老化時間。

The second part of the output is the table showing interface STP information, in particular STP role, STP status, STP cost, STP interface priority, and STP type, for all interfaces that are part of the VLAN that you specified in the command.

輸出的第二部分是表格，顯示介面的 STP 資訊，包括你在指令中指定的 VLAN 內所有介面的 STP 角色、STP 狀態、STP 成本、STP 介面優先權，以及 STP 類型。

Both Eternet0/2 and 0/3 connect to SW3, but only Ethernet0/2 is forwarding traffic. The STP is blocking Ethernet0/3 to prevent a loop. Only half of the potential bandwidth in this pair of links is in use. Ethernet 0/0 and Ethernet 0/1 interfaces are both in the blocking state. They are not forwarding traffic. All interfaces have STP cost of 100.

Ethernet0/2 與 0/3 都連接到 SW3，但只有 Ethernet0/2 在轉送流量。STP 正在阻斷 Ethernet0/3 以防止迴圈。這對連結中僅有一半的潛在頻寬被使用。Ethernet 0/0 與 Ethernet 0/1 介面都處於阻斷狀態，並未轉送流量。所有介面的 STP 成本都是 100。

To determine the resulting STP topology for VLAN 10, you need to examine the STP information on other switches also.

要判斷 VLAN 10 最終的 STP 拓樸，你也需要檢視其他交換器上的 STP 資訊。

To identify the root switch in the topology, follow the direction in which the Root port is facing. In this case, the Root port is Etherent0/2 facing toward SW3. On SW3, enter the show spanning-tree vlan 10 command.

若要找出拓樸中的根交換器，可依照根埠所指方向追蹤。在此案例中，根埠是朝向 SW3 的 Ethernet0/2。在 SW3 上，輸入 show spanning-tree vlan 10 指令。

Notice the previously mentioned This bridge is the root message—you have discovered the root switch. Also notice that none of the interfaces have the Root role, they are all designated ports, which is another indicator that you have discovered the root switch.

請注意先前提到的「本橋接器即為根」訊息，這表示你已找到根交換器。另外也請留意，沒有任何介面具有根埠角色，全部都是指定埠，這也是另一個判斷你已找到根交換器的指標。

After you examine STP information for VLAN 10 on all the switches, the resulting topology should look like the one in the following figure.

在你檢視所有交換器上 VLAN 10 的 STP 資訊之後，最終的拓樸應如下圖所示。

Also, examine the STP configuration for other VLANs and determine the STP topology for VLAN 20 and VLAN 1. For your reference, these two STP topologies are also shown below.

另外，也請檢視其他 VLAN 的 STP 設定，判斷 VLAN 20 與 VLAN 1 的 STP 拓樸。作為參考，這兩個 STP 拓樸也顯示於下方。

To better utilize the links between the SW1 and SW3 switches, you will aggregate them into a Layer 2 EtherChannel link. Start the configuration by shutting down interfaces Ethernet0/2 and Ethernet0/3 on the SW1 switch. Disable both interfaces at the same time.

為了更有效利用 SW1 與 SW3 交換器之間的連結，你將把它們聚合成一條第 2 層 EtherChannel 連結。先在 SW1 交換器上關閉 Ethernet0/2 與 Ethernet0/3 介面，開始進行設定。請同時停用這兩個介面。

On SW1, enter the following commands:

在 SW1 上，輸入以下指令：

Having interfaces disabled while you are configuring them ensures that the incomplete configuration will not create activity on the link.

在設定過程中停用介面，可確保不完整的設定不會在連結上產生活動。

Shut down interfaces Ethernet0/2 and Ethernet0/3 on switch SW3.

在 SW3 交換器上關閉 Ethernet0/2 與 Ethernet0/3 介面。

On SW3, enter the following commands:

在 SW3 上，輸入以下指令：

On SW1, bundle Ethernet0/2 and Ethernet 0/3 interfaces to the logical interface port-channel 1. The aggregation should be negotiated by the LACP protocol.

在 SW1 上，將 Ethernet0/2 與 Ethernet 0/3 介面綁定到邏輯介面 port-channel 1。聚合應由 LACP 協定協商。

On SW1, enter the following commands:

在 SW1 上，輸入以下指令：

On SW3, bundle Ethernet0/2 and Ethernet 0/3 to logical interface port channel 1 using the LACP protocol active mode.

在 SW3 上，使用 LACP 協定的主動模式，將 Ethernet0/2 與 Ethernet 0/3 綁定到邏輯介面 port channel 1。

On SW3, enter the following commands:

在 SW3 上，輸入以下指令：

Note that you have configured both sides of the links to be in the LACP active state, which means to actively negotiate link aggregation. For successful aggregation, it would be enough to have only one side operating in the LACP active mode; the other could be configured to be in passive mode.

請注意，你已將兩側的連結都設定為 LACP 主動狀態，表示雙方都會主動協商鏈路聚合。要成功聚合，其實只要一側設為 LACP 主動模式即可，另一側可設定為被動模式。

Ethernet 0/2 and Ethernet 0/3 interfaces on both switches have a matching configuration regarding the following: speed and duplex attributes, switchport mode set to trunk, native VLAN, and all allowed VLANs on the trunk. Thus, the preconditions for successful establishment of the EtherChannel link are fulfilled. You can enable interfaces Ethernet0/2 and Ethernet0/3 on switch SW1.

兩台交換器上的 Ethernet 0/2 與 Ethernet 0/3 介面，在速度與雙工屬性、switchport 模式設為 trunk、原生 VLAN，以及中繼上允許的所有 VLAN 等方面均相符。因此，成功建立 EtherChannel 連結的先決條件已滿足。你可以在 SW1 交換器上啟用 Ethernet0/2 與 Ethernet0/3 介面。

On SW1, enter the following commands:

在 SW1 上，輸入以下指令：

Enable interfaces Ethernet0/2 and Ethernet0/3 on switch SW3.

在 SW3 交換器上啟用 Ethernet0/2 與 Ethernet0/3 介面。

On SW3, enter the following commands:

在 SW3 上，輸入以下指令：

Line protocol for physical interfaces Ethernet 0/2 and Ethernet 0/3 changes state to up. Logical interface port channel 1 also transitions to the up state.

實體介面 Ethernet 0/2 與 Ethernet 0/3 的線路協定狀態轉為 up。邏輯介面 port channel 1 也隨之轉為 up 狀態。

Add the description EChannel to SW3 to port channel 1 interface on SW1 switch.

在 SW1 交換器的 port channel 1 介面上新增描述 description EChannel to SW3。

On SW1, enter the following commands:

在 SW1 上，輸入以下指令：

Add the description EChannel to SW1 to port channel 1 interface on SW3 switch.

在 SW3 交換器的 port channel 1 介面上新增描述 description EChannel to SW1。

On SW3, enter the following commands:

在 SW3 上，輸入以下指令：

Display the interface status summary on SW1.

顯示 SW1 上的介面狀態摘要。

On SW1, enter the following command:

在 SW1 上，輸入以下指令：

Ethernet0/2 and 0/3 information is still present in the output, like when you first displayed interface statuses. In addition, now Po1 is also listed. The port channel is up on SW1.

Ethernet0/2 與 0/3 的資訊仍如你第一次顯示介面狀態時一樣存在。此外，現在也列出了 Po1。port channel 在 SW1 上已啟動。

Display the interface status summary on SW3.

顯示 SW3 上的介面狀態摘要。

On SW3, enter the following command:

在 SW3 上，輸入以下指令：

Port Po1 is listed in the output, along with all other SW3 interfaces. The port channel is up on SW3.

輸出中列出了 Po1 連接埠，以及 SW3 的所有其他介面。port channel 在 SW3 上已啟動。

To analyze whether and how the bundling of ports affected the STP topology, display the spanning tree information for VLAN 10 on SW1 again. You should notice changes compared to what you were seeing before the links were aggregated.

為了分析連接埠綁定是否以及如何影響 STP 拓樸，請再次在 SW1 上顯示 VLAN 10 的生成樹資訊。你應該會注意到與連結聚合之前所見到的情況有所不同。

On SW1, enter the following command:

在 SW1 上，輸入以下指令：

If you display spanning tree information quickly enough, you may find interfaces Ethernet0/0 and 0/1 in listening or learning state. If so, repeat the command until all interfaces are in the forwarding state. The cost of the port channel is 56, which is much lower than the cost of 100, assigned to individual interfaces.

如果你夠快顯示生成樹資訊，可能會發現介面 Ethernet0/0 與 0/1 處於偵聽（listening）或學習（learning）狀態。若是如此，請重複執行該指令，直到所有介面都進入轉送（forwarding）狀態為止。port channel 的成本是 56，遠低於個別介面的成本 100。

Ethernet0/2 and 0/3 are no longer visible to the spanning tree. Instead, they have been replaced by the logical port channel 1 interface. The port channel is in the forwarding state. The forwarding state implies that the port channel is forwarding on all member interfaces. The cost of the port channel is 56, which is much lower than the cost of 100, assigned to individual interfaces. The following figure shows the STP topology for VLAN 10, after the link aggregation.

Ethernet0/2 與 0/3 在生成樹中已不再可見，取而代之的是邏輯介面 port channel 1。該 port channel 處於轉送狀態，這代表 port channel 會在所有成員介面上進行轉送。port channel 的成本是 56，遠低於個別介面的成本 100。下圖顯示鏈路聚合後 VLAN 10 的 STP 拓樸。

The Ethernet0/0 and Ethernet 0/1 are not in the blocking state any more. They are now forwarding. These interfaces connect to SW4. Since the path from SW1 back to the root (SW3) now costs less due to the port channel establishment, its ports have been selected as the designated ports for these two links. However, the ports on SW4 side of the links are now in the blocking state, which you can verify by issuing the show spanning-tree vlan 10 command on SW4:

Ethernet0/0 與 Ethernet 0/1 不再處於阻斷狀態，而是開始轉送。這些介面連接到 SW4。由於建立 port channel 後，從 SW1 回到根交換器（SW3）的路徑成本降低，因此其連接埠已被選為這兩條連結的指定埠。然而，連結在 SW4 那一側的連接埠現在處於阻斷狀態，你可以在 SW4 上執行 show spanning-tree vlan 10 指令加以驗證：

Note that aggregating links does not affect STP root switch selection. The root selection is based on the switch STP priority and its MAC address.

請注意，聚合連結並不會影響 STP 根交換器的選擇。根交換器的選擇是根據交換器的 STP 優先權及其 MAC 位址決定的。

Now that you have successfully configured link aggregation, verify the configuration by displaying the interface information of the port channel 1 interface on SW1.

既然你已成功設定鏈路聚合，請透過顯示 SW1 上 port channel 1 介面的介面資訊來驗證設定。

On SW1, enter the following command:

在 SW1 上，輸入以下指令：

From the output, you can determine that the port channel 1 bundles Ethernet0/2 and Ethernet 0/3 interfaces, and that the logical bandwidth of the aggregated link is 20 Mbps (20000 Kbit/s), twice the bandwidth of the individual interfaces.

從輸出中可以判斷，port channel 1 綁定了 Ethernet0/2 與 Ethernet 0/3 介面，且聚合連結的邏輯頻寬為 20 Mbps（20000 Kbit/s），是個別介面頻寬的兩倍。

To view aggregation details, such as aggregation method and how long the aggregated link has been up, display the detailed EtherChannel information on SW1.

若要檢視聚合詳細資訊，例如聚合方法以及聚合連結已啟動多久，請在 SW1 上顯示詳細的 EtherChannel 資訊。

On SW1, enter the following command:

在 SW1 上，輸入以下指令：

From the output, you can determine that the number of ports in this port channel is two. The members are the Ethernet0/2 and Ethernet0/3 interfaces. The protocol that was used to build the bundle is LACP.

從輸出中可以判斷，此 port channel 中的連接埠數量為兩個，成員是 Ethernet0/2 與 Ethernet0/3 介面。用來建立此綁定的協定是 LACP。

View summarized information about the aggregated EtherChannel links on the SW1 switch.

在 SW1 交換器上檢視聚合 EtherChannel 連結的摘要資訊。

On SW1, enter the following command:

在 SW1 上，輸入以下指令：

The EtherChannel information is shown in one line, and includes EtherChannel type, status of the port channel interface and its member interfaces, and aggregation method. From the output, you can determine that the Layer 2 port channel 1 is operational (indicated by SU flags), that it has two member interfaces that are both active in the aggregated link (indicated by the P flag), and that aggregation was performed using LACP.

EtherChannel 資訊以一行顯示，包括 EtherChannel 類型、port channel 介面及其成員介面的狀態，以及聚合方法。從輸出中可以判斷，第 2 層 port channel 1 正在運作（以 SU 旗標表示），它有兩個成員介面，且都在聚合連結中處於作用中狀態（以 P 旗標表示），聚合是透過 LACP 完成的。