这三条命令是v5的环路检测吗，对应v7什么命令

  环路检测基本功能配置举例

1. 组网需求

·     三台设备Device A、Device B和Device C组成一个物理上的环形网络。

·     通过在Device A上配置环路检测功能，使系统能够自动关闭Device A上出现环路的端口，并通过打印日志信息来通知用户检查网络。

2. 组网图

图1-3 环路检测基本功能配置组网图

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3. 配置步骤

(1)     配置Device A

# 创建VLAN 100，并全局开启该VLAN内的环路检测功能。

<DeviceA> system-view

[DeviceA] vlan 100

[DeviceA–vlan100] quit

[DeviceA] loopback-detection global enable vlan 100

# 配置端口Ten-GigabitEthernet1/0/1和Ten-GigabitEthernet1/0/2为Trunk类型，并允许VLAN 100通过。

[DeviceA] interface ten-gigabitethernet 1/0/1

[DeviceA-Ten-GigabitEthernet1/0/1] port link-type trunk

[DeviceA-Ten-GigabitEthernet1/0/1] port trunk permit vlan 100

[DeviceA-Ten-GigabitEthernet1/0/1] quit

[DeviceA] interface ten-gigabitethernet 1/0/2

[DeviceA-Ten-GigabitEthernet1/0/2] port link-type trunk

[DeviceA-Ten-GigabitEthernet1/0/2] port trunk permit vlan 100

[DeviceA-Ten-GigabitEthernet1/0/2] quit

# 全局配置环路检测的处理模式为Shutdown模式。

[DeviceA] loopback-detection global action shutdown

# 配置环路检测的时间间隔为35秒。

[DeviceA] loopback-detection interval-time 35

(2)     配置Device B

# 创建VLAN 100。

<DeviceB> system-view

[DeviceB] vlan 100

[DeviceB–vlan100] quit

# 配置端口Ten-GigabitEthernet1/0/1和Ten-GigabitEthernet1/0/2为Trunk类型，并允许VLAN 100通过。

[DeviceB] interface ten-gigabitethernet 1/0/1

[DeviceB-Ten-GigabitEthernet1/0/1] port link-type trunk

[DeviceB-Ten-GigabitEthernet1/0/1] port trunk permit vlan 100

[DeviceB-Ten-GigabitEthernet1/0/1] quit

[DeviceB] interface ten-gigabitethernet 1/0/2

[DeviceB-Ten-GigabitEthernet1/0/2] port link-type trunk

[DeviceB-Ten-GigabitEthernet1/0/2] port trunk permit vlan 100

[DeviceB-Ten-GigabitEthernet1/0/2] quit

(3)     配置Device C

# 创建VLAN 100。

<DeviceC> system-view

[DeviceC] vlan 100

[DeviceC–vlan100] quit

# 配置端口Ten-GigabitEthernet1/0/1和Ten-GigabitEthernet1/0/2为Trunk类型，并允许VLAN 100通过。

[DeviceC] interface ten-gigabitethernet 1/0/1

[DeviceC-Ten-GigabitEthernet1/0/1] port link-type trunk

[DeviceC-Ten-GigabitEthernet1/0/1] port trunk permit vlan 100

[DeviceC-Ten-GigabitEthernet1/0/1] quit

[DeviceC] interface ten-gigabitethernet 1/0/2

[DeviceC-Ten-GigabitEthernet1/0/2] port link-type trunk

[DeviceC-Ten-GigabitEthernet1/0/2] port trunk permit vlan 100

[DeviceC-Ten-GigabitEthernet1/0/2] quit

4. 验证配置

当配置完成后，系统在一个环路检测时间间隔内在Device A的端口Ten-GigabitEthernet1/0/1和Ten-GigabitEthernet1/0/2上都检测到了环路，于是将这两个端口自动关闭，并打印了如下日志信息：

[DeviceA]

%Feb 24 15:04:29:663 2013 DeviceA LPDT/4/LPDT_LOOPED: A loop was detected on Ten-GigabitEthernet1/0/1.

%Feb 24 15:04:29:664 2013 DeviceA LPDT/4/LPDT_VLAN_LOOPED: A loop was detected on Ten-GigabitEthernet1/0/1 in VLAN 100.

%Feb 24 15:04:29:667 2013 DeviceA LPDT/4/LPDT_LOOPED: A loop was detected on Ten-GigabitEthernet1/0/2.

%Feb 24 15:04:29:668 2013 DeviceA LPDT/4/LPDT_VLAN_LOOPED: A loop was detected on Ten-GigabitEthernet1/0/2 in VLAN 100.

%Feb 24 15:04:44:243 2013 DeviceA LPDT/5/LPDT_VLAN_RECOVERED: A loop was removed on Ten-GigabitEthernet1/0/1 in VLAN 100.

%Feb 24 15:04:44:243 2013 DeviceA LPDT/5/LPDT_RECOVERED: All loops were removed on Ten-GigabitEthernet1/0/1.

%Feb 24 15:04:44:248 2013 DeviceA LPDT/5/LPDT_VLAN_RECOVERED: A loop was removed on Ten-GigabitEthernet1/0/2 in VLAN 100.

%Feb 24 15:04:44:248 2013 DeviceA LPDT/5/LPDT_RECOVERED: All loops were removed on Ten-GigabitEthernet1/0/2.

使用display loopback-detection命令可以查看Device A上环路检测的配置和运行情况：

# 显示Device A上环路检测的配置和运行情况。

[DeviceA] display loopback-detection

Loop detection is enabled.

Loop detection interval is 35 second(s).

No loop is detected.

由此可见，Device A上并未显示在端口Ten-GigabitEthernet1/0/1和Ten-GigabitEthernet1/0/2上检测到环路，这是由于环路检测功能运行在Shutdown模式下，端口Ten-GigabitEthernet1/0/1和Ten-GigabitEthernet1/0/2上出现环路后均已被自动关闭，因此这两个端口上的环路已消除。此时，使用display interface命令分别查看Device A上端口Ten-GigabitEthernet1/0/1和Ten-GigabitEthernet1/0/2的状态信息：

# 显示Device A上端口Ten-GigabitEthernet1/0/1的状态信息。

[DeviceA] display interface ten-gigabitethernet 1/0/1

Ten-GigabitEthernet1/0/1 current state: DOWN (Loopback detection down)

...

# 显示Device A上端口Ten-GigabitEthernet1/0/2的状态信息。

[DeviceA] display interface ten-gigabitethernet 1/0/2

Ten-GigabitEthernet1/0/2 current state: DOWN (Loopback detection down)

...

由此可见，端口Ten-GigabitEthernet1/0/1和Ten-GigabitEthernet1/0/2均已被环路检测模块自动关闭。

loopback-detection enable  开启环路检测功能

 loopback-detection control enable    使能Trunk接口的环路阻断功能

 loopback-detection per-vlan enable  配置在Trunk端口和Hybrid端口允许通过的所有VLAN内进行环回监测

V7缺省情况下，当系统检测到端口出现环路时不对该端口进行任何处理，仅生成日志信息 。

loopback-detection enable vlan all