S5560

DLDP配置举例（自动模式）

1. 组网需求

·            Device A和Device B各自的接口GigabitEthernet1/0/1和GigabitEthernet1/0/2之间分别通过一对光纤进行连接。

·            要求通过配置DLDP功能，使接口上发生单向链路故障后由DLDP自动关闭故障接口，并在网络管理员排除故障后，故障接口自动恢复。

2. 组网图

图1-5 DLDP配置组网图（自动模式）

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3. 配置步骤

(1)       配置Device A

# 全局开启DLDP功能。

<DeviceA> system-view

[DeviceA] dldp global enable

# 在接口GigabitEthernet1/0/1上配置双工模式为全双工、接口速率为1000Mbps，并开启DLDP功能。

[DeviceA] interface gigabitethernet 1/0/1

[DeviceA-GigabitEthernet1/0/1] duplex full

[DeviceA-GigabitEthernet1/0/1] speed 1000

[DeviceA-GigabitEthernet1/0/1] dldp enable

[DeviceA-GigabitEthernet1/0/1] quit

# 在接口GigabitEthernet1/0/2上配置双工模式为全双工、接口速率为1000Mbps，并开启DLDP功能。

[DeviceA] interface gigabitethernet 1/0/2

[DeviceA-GigabitEthernet1/0/2] duplex full

[DeviceA-GigabitEthernet1/0/2] speed 1000

[DeviceA-GigabitEthernet1/0/2] dldp enable

[DeviceA-GigabitEthernet1/0/2] quit

# 配置DLDP发现单向链路后接口的关闭模式为自动模式。

[DeviceA] dldp unidirectional-shutdown auto

(2)       配置Device B

# 全局开启DLDP功能。

<DeviceB> system-view

[DeviceB] dldp global enable

# 在接口GigabitEthernet1/0/1上配置双工模式为全双工、接口速率为1000Mbps，并开启DLDP功能。

[DeviceB] interface gigabitethernet 1/0/1

[DeviceB-GigabitEthernet1/0/1] duplex full

[DeviceB-GigabitEthernet1/0/1] speed 1000

[DeviceB-GigabitEthernet1/0/1] dldp enable

[DeviceB-GigabitEthernet1/0/1] quit

# 在接口GigabitEthernet1/0/2上配置双工模式为全双工、接口速率为1000Mbps，并开启DLDP功能。

[DeviceB] interface gigabitethernet 1/0/2

[DeviceB-GigabitEthernet1/0/2] duplex full

[DeviceB-GigabitEthernet1/0/2] speed 1000

[DeviceB-GigabitEthernet1/0/2] dldp enable

[DeviceB-GigabitEthernet1/0/2] quit

# 配置DLDP发现单向链路后接口的关闭模式为自动模式。

[DeviceB] dldp unidirectional-shutdown auto

4. 验证配置

配置完成后，通过使用display dldp命令可以查看DLDP的全局配置信息和接口上的DLDP信息。例如：

# 查看Device A上DLDP的全局配置信息和所有接口上的DLDP信息。

[DeviceA] display dldp

 DLDP global status: Enabled

 DLDP advertisement interval: 5s

 DLDP authentication-mode: None

 DLDP unidirectional-shutdown mode: Auto

 DLDP delaydown-timer value: 1s

 Number of enabled ports: 2

Interface GigabitEthernet1/0/1

 DLDP port state: Bidirectional

 Number of the port’s neighbors: 1

  Neighbor MAC address: 0023-8956-3600

  Neighbor port index: 1

  Neighbor state: Confirmed

  Neighbor aged time: 11s

Interface GigabitEthernet1/0/2

 DLDP port state: Bidirectional

 Number of the port’s neighbors: 1

  Neighbor MAC address: 0023-8956-3600

  Neighbor port index: 2

  Neighbor state: Confirmed

  Neighbor aged time: 12s

以上信息表明，接口GigabitEthernet1/0/1和GigabitEthernet1/0/2上的DLDP接口状态均为Bidirectional，说明这两个接口所在的链路均处于双通状态。

# 在Device A上配置允许日志信息输出到当前终端，且输出的日志信息最低为6级。

[DeviceA] quit

<DeviceA> terminal monitor

<DeviceA> terminal logging level 6

此后某刻，Device A上输出了以下日志信息：

<DeviceA>%Jul 11 17:40:31:089 2012 DeviceA IFNET/3/PHY_UPDOWN: GigabitEthernet1/0/1 link status is DOWN.

%Jul 11 17:40:31:091 2012 DeviceA IFNET/5/LINK_UPDOWN: Line protocol on the interface GigabitEthernet1/0/1 is DOWN.

%Jul 11 17:40:31:677 2012 DeviceA IFNET/3/PHY_UPDOWN: GigabitEthernet1/0/2 link status is DOWN.

%Jul 11 17:40:31:678 2012 DeviceA IFNET/5/LINK_UPDOWN: Line protocol on the interface GigabitEthernet1/0/2 is DOWN.

%Jul 11 17:40:38:544 2012 DeviceA IFNET/3/PHY_UPDOWN: GigabitEthernet1/0/1 link status is UP.

%Jul 11 17:40:38:836 2012 DeviceA IFNET/3/PHY_UPDOWN: GigabitEthernet1/0/2 link status is UP.

以上信息表明，接口GigabitEthernet1/0/1和GigabitEthernet1/0/2的物理状态都先down后up，而链路状态则都down后未再up。网络管理员进行进一步检查：

# 查看Device A上DLDP的全局配置信息和所有接口上的DLDP信息。

<DeviceA> display dldp

 DLDP global status: Enabled

 DLDP advertisement interval: 5s

 DLDP authentication-mode: None

 DLDP unidirectional-shutdown mode: Auto

 DLDP delaydown-timer value: 1s

 Number of enabled ports: 2

Interface GigabitEthernet1/0/1

 DLDP port state: Unidirectional

 Number of the port’s neighbors: 0 (Maximum number ever detected: 1)

Interface GigabitEthernet1/0/2

 DLDP port state: Unidirectional

 Number of the port’s neighbors: 0 (Maximum number ever detected: 1)

以上信息表明，接口GigabitEthernet1/0/1和GigabitEthernet1/0/2上的DLDP接口状态均为Unidirectional，说明这两个接口所在的链路均处于单通状态。

由此可知，DLDP在接口GigabitEthernet1/0/1和GigabitEthernet1/0/2上都检测到了单向链路，并自动关闭了这两个接口。经检查，网络管理员发现连接Device A和Device B的两对光纤被错误地进行了交叉连接，于是他将这两对光纤重新进行了正确连接。随后，Device A上输出了以下日志信息：

<DeviceA>%Jul 11 17:42:57:709 2012 DeviceA IFNET/3/PHY_UPDOWN: GigabitEthernet1/0/1 link status is DOWN.

%Jul 11 17:42:58:603 2012 DeviceA IFNET/3/PHY_UPDOWN: GigabitEthernet1/0/2 link status is DOWN.

%Jul 11 17:43:02:342 2012 DeviceA IFNET/3/PHY_UPDOWN: GigabitEthernet1/0/1 link status is UP.

%Jul 11 17:43:02:343 2012 DeviceA DLDP/6/DLDP_NEIGHBOR_CONFIRMED: A neighbor was confirmed on interface GigabitEthernet1/0/1. The neighbor"s system MAC is 0023-8956-3600, and the port index is 1.

%Jul 11 17:43:02:344 2012 DeviceA DLDP/6/DLDP_LINK_BIDIRECTIONAL: DLDP detected a bidirectional link on interface GigabitEthernet1/0/1.

%Jul 11 17:43:02:353 2012 DeviceA IFNET/5/LINK_UPDOWN: Line protocol on the interface GigabitEthernet1/0/1 is UP.

%Jul 11 17:43:02:357 2012 DeviceA IFNET/3/PHY_UPDOWN: GigabitEthernet1/0/2 link status is UP.

%Jul 11 17:43:02:362 2012 DeviceA DLDP/6/DLDP_NEIGHBOR_CONFIRMED: A neighbor was confirmed on interface GigabitEthernet1/0/2. The neighbor"s system MAC is 0023-8956-3600, and the port index is 2.

%Jul 11 17:43:02:362 2012 DeviceA DLDP/6/DLDP_LINK_BIDIRECTIONAL: DLDP detected a bidirectional link on interface GigabitEthernet1/0/2.

%Jul 11 17:43:02:368 2012 DeviceA IFNET/5/LINK_UPDOWN: Line protocol on the interface GigabitEthernet1/0/2 is UP.

以上信息表明，接口GigabitEthernet1/0/1和GigabitEthernet1/0/2的物理状态和链路状态均已up，并各自确定了DLDP邻居，所在链路也变为双通状态。

1.9.2  DLDP配置举例（手动模式）

1. 组网需求

·            Device A和Device B各自的接口GigabitEthernet1/0/1和GigabitEthernet1/0/2之间分别通过一对光纤进行连接。

·            要求通过配置DLDP功能，使接口上发生单向链路故障后，需要由网络管理员手工关闭和恢复故障接口。

2. 组网图

图1-6 DLDP配置组网图（手动模式）

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3. 配置步骤

(1)       配置Device A

# 全局开启DLDP功能。

<DeviceA> system-view

[DeviceA] dldp global enable

# 在接口GigabitEthernet1/0/1上配置双工模式为全双工、接口速率为1000Mbps，并开启DLDP功能。

[DeviceA] interface gigabitethernet 1/0/1

[DeviceA-GigabitEthernet1/0/1] duplex full

[DeviceA-GigabitEthernet1/0/1] speed 1000

[DeviceA-GigabitEthernet1/0/1] dldp enable

[DeviceA-GigabitEthernet1/0/1] quit

# 在接口GigabitEthernet1/0/2上配置双工模式为全双工、接口速率为1000Mbps，并开启DLDP功能。

[DeviceA] interface gigabitethernet 1/0/2

[DeviceA-GigabitEthernet1/0/2] duplex full

[DeviceA-GigabitEthernet1/0/2] speed 1000

[DeviceA-GigabitEthernet1/0/2] dldp enable

[DeviceA-GigabitEthernet1/0/2] quit

# 配置DLDP发现单向链路后接口的关闭模式为手动模式。

[DeviceA] dldp unidirectional-shutdown manual

(2)       配置Device B

# 全局开启DLDP功能。

<DeviceB> system-view

[DeviceB] dldp global enable

# 在接口GigabitEthernet1/0/1上配置双工模式为全双工、接口速率为1000Mbps，并开启DLDP功能。

[DeviceB] interface gigabitethernet 1/0/1

[DeviceB-GigabitEthernet1/0/1] duplex full

[DeviceB-GigabitEthernet1/0/1] speed 1000

[DeviceB-GigabitEthernet1/0/1] dldp enable

[DeviceB-GigabitEthernet1/0/1] quit

# 在接口GigabitEthernet1/0/2上配置双工模式为全双工、接口速率为1000Mbps，并开启DLDP功能。

[DeviceB] interface gigabitethernet 1/0/2

[DeviceB-GigabitEthernet1/0/2] duplex full

[DeviceB-GigabitEthernet1/0/2] speed 1000

[DeviceB-GigabitEthernet1/0/2] dldp enable

[DeviceB-GigabitEthernet1/0/2] quit

# 配置DLDP发现单向链路后接口的关闭模式为手动模式。

[DeviceB] dldp unidirectional-shutdown manual

4. 验证配置

配置完成后，通过使用display dldp命令可以查看DLDP的全局配置信息和接口上的DLDP信息。例如：

# 查看Device A上DLDP的全局配置信息和所有接口上的DLDP信息。

[DeviceA] display dldp

 DLDP global status: Enabled

 DLDP advertisement interval: 5s

 DLDP authentication-mode: None

 DLDP unidirectional-shutdown mode: Manual

 DLDP delaydown-timer value: 1s

 Number of enabled ports: 2

Interface GigabitEthernet1/0/1

 DLDP port state: Bidirectional

 Number of the port’s neighbors: 1

  Neighbor MAC address: 0023-8956-3600

  Neighbor port index: 1

  Neighbor state: Confirmed

  Neighbor aged time: 11s

Interface GigabitEthernet1/0/2

 DLDP port state: Bidirectional

 Number of the port’s neighbors: 1

  Neighbor MAC address: 0023-8956-3600

  Neighbor port index: 2

  Neighbor state: Confirmed

  Neighbor aged time: 12s

以上信息表明，接口GigabitEthernet1/0/1和GigabitEthernet1/0/2上的DLDP接口状态均为Bidirectional，说明这两个接口所在的链路均处于双通状态。

# 在Device A上配置允许日志信息输出到当前终端，且输出的日志信息最低为6级。

[DeviceA] quit

<DeviceA> terminal monitor

<DeviceA> terminal logging level 6

此后某刻，网络管理员在Device A上看到如下Log信息：

<DeviceA>%Jul 12 08:29:17:786 2012 DeviceA IFNET/3/PHY_UPDOWN: GigabitEthernet1/0/1 link status is DOWN.

%Jul 12 08:29:17:787 2012 DeviceA IFNET/5/LINK_UPDOWN: Line protocol on the interface GigabitEthernet1/0/1 is DOWN.

%Jul 12 08:29:17:800 2012 DeviceA IFNET/3/PHY_UPDOWN: GigabitEthernet1/0/2 link status is DOWN.

%Jul 12 08:29:17:800 2012 DeviceA IFNET/5/LINK_UPDOWN: Line protocol on the interface GigabitEthernet1/0/2 is DOWN.

%Jul 12 08:29:25:004 2012 DeviceA IFNET/3/PHY_UPDOWN: GigabitEthernet1/0/1 link status is UP.

%Jul 12 08:29:25:005 2012 DeviceA IFNET/5/LINK_UPDOWN: Line protocol on the interface GigabitEthernet1/0/1 is UP.

%Jul 12 08:29:25:893 2012 DeviceA IFNET/3/PHY_UPDOWN: GigabitEthernet1/0/2 link status is UP.

%Jul 12 08:29:25:894 2012 DeviceA IFNET/5/LINK_UPDOWN: Line protocol on the interface GigabitEthernet1/0/2 is UP.

以上信息表明，接口GigabitEthernet1/0/1和GigabitEthernet1/0/2的物理状态和链路状态都先down后up。网络管理员进行进一步检查：

# 查看Device A上DLDP的全局配置信息和所有接口上的DLDP信息。

<DeviceA> display dldp

 DLDP global status: Enabled

 DLDP advertisement interval: 5s

 DLDP authentication-mode: None

 DLDP unidirectional-shutdown mode: Manual

 DLDP delaydown-timer value: 1s

 Number of enabled ports: 2

Interface GigabitEthernet1/0/1

 DLDP port state: Unidirectional

 Number of the port’s neighbors: 0 (Maximum number ever detected: 1)

Interface GigabitEthernet1/0/2

 DLDP port state: Unidirectional

 Number of the port’s neighbors: 0 (Maximum number ever detected: 1)

以上信息表明，接口GigabitEthernet1/0/1和GigabitEthernet1/0/2上的DLDP接口状态均为Unidirectional，说明这两个接口所在的链路均处于单通状态。

由此可知，DLDP在接口GigabitEthernet1/0/1和GigabitEthernet1/0/2上都检测到了单向链路，但并未关闭这两个接口。经检查，网络管理员发现连接Device A和Device B的两对光纤被错误地进行了交叉连接，于是他分别将Device A的两个接口手工关闭：

# 关闭接口GigabitEthernet1/0/1。

<DeviceA> system-view

[DeviceA] interface gigabitethernet 1/0/1

[DeviceA-GigabitEthernet1/0/1] shutdown

Device A上随即输出以下日志信息：

[DeviceA-GigabitEthernet1/0/1]%Jul 12 08:34:23:717 2012 DeviceA IFNET/3/PHY_UPDOWN: GigabitEthernet1/0/1 link status is DOWN.

%Jul 12 08:34:23:718 2012 DeviceA IFNET/5/LINK_UPDOWN: Line protocol on the interface GigabitEthernet1/0/1 is DOWN.

%Jul 12 08:34:23:778 2012 DeviceA IFNET/3/PHY_UPDOWN: GigabitEthernet1/0/2 link status is DOWN.

%Jul 12 08:34:23:779 2012 DeviceA IFNET/5/LINK_UPDOWN: Line protocol on the interface GigabitEthernet1/0/2 is DOWN.

以上信息表明，接口GigabitEthernet1/0/1和GigabitEthernet1/0/2的物理状态和链路状态均已变为down。

# 关闭接口GigabitEthernet1/0/2。

[DeviceA-GigabitEthernet1/0/1] quit

[DeviceA] interface gigabitethernet 1/0/2

[DeviceA-GigabitEthernet1/0/2] shutdown

然后，网络管理员将连接Device A和Device B的两对光纤重新进行了正确连接，检查无误后，他又分别将Device A的两个接口重新打开：

# 打开接口GigabitEthernet1/0/2。

[DeviceA-GigabitEthernet1/0/2] undo shutdown

Device A上随即输出以下日志信息：

[DeviceA-GigabitEthernet1/0/2]%Jul 12 08:46:17:677 2012 DeviceA IFNET/3/PHY_UPDOWN: GigabitEthernet1/0/2 link status is UP.

%Jul 12 08:46:17:678 2012 DeviceA IFNET/5/LINK_UPDOWN: Line protocol on the interface GigabitEthernet1/0/2 is UP.

%Jul 12 08:46:17:959 2012 DeviceA DLDP/6/DLDP_NEIGHBOR_CONFIRMED: A neighbor was confirmed on interface GigabitEthernet1/0/2. The neighbor"s system MAC is 0023-8956-3600, and the port index is 2.

%Jul 12 08:46:17:959 2012 DeviceA DLDP/6/DLDP_LINK_BIDIRECTIONAL: DLDP detected a bidirectional link on interface GigabitEthernet1/0/2.

以上信息表明，接口GigabitEthernet1/0/2的物理状态和链路状态均已up，并确定了DLDP邻居，所在链路也变为双通状态。

# 打开接口GigabitEthernet1/0/1。

[DeviceA-GigabitEthernet1/0/2] quit

[DeviceA] interface gigabitethernet 1/0/1

[DeviceA-GigabitEthernet1/0/1] undo shutdown

Device A上随即输出以下日志信息：

[DeviceA-GigabitEthernet1/0/1]%Jul 12 08:48:25:952 2012 DeviceA IFNET/3/PHY_UPDOWN: GigabitEthernet1/0/1 link status is UP.

%Jul 12 08:48:25:952 2012 DeviceA DLDP/6/DLDP_NEIGHBOR_CONFIRMED: A neighbor was confirmed on interface GigabitEthernet1/0/1. The neighbor"s system MAC is 0023-8956-3600, and the port index is 1.

%Jul 12 08:48:25:953 2012 DeviceA IFNET/5/LINK_UPDOWN: Line protocol on the interface GigabitEthernet1/0/1 is UP.

%Jul 12 08:48:25:953 2012 DeviceA DLDP/6/DLDP_LINK_BIDIRECTIONAL: DLDP detected a bidirectional link on interface GigabitEthernet1/0/1.

以上信息表明，接口GigabitEthernet1/0/1的物理状态和链路状态均已up，并确定了DLDP邻居，所在链路也变为双通状态。

1.9.3  DLDP配置举例（混合模式）

1. 组网需求

·            Device A和Device B各自的接口GigabitEthernet1/0/1和GigabitEthernet1/0/2之间分别通过一对光纤进行连接。

·            要求通过配置DLDP功能，使接口上发生单向链路故障后由DLDP自动关闭故障接口，并在网络管理员排除故障后，手工恢复故障接口。

2. 组网图

图1-7 DLDP配置组网图（混合模式）

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3. 配置步骤

(1)       配置Device A

# 全局开启DLDP功能。

<DeviceA> system-view

[DeviceA] dldp global enable

# 在接口GigabitEthernet1/0/1上配置双工模式为全双工、接口速率为1000Mbps，并开启DLDP功能。

[DeviceA] interface gigabitethernet 1/0/1

[DeviceA-GigabitEthernet1/0/1] duplex full

[DeviceA-GigabitEthernet1/0/1] speed 1000

[DeviceA-GigabitEthernet1/0/1] dldp enable

[DeviceA-GigabitEthernet1/0/1] quit

# 在接口GigabitEthernet1/0/2上配置双工模式为全双工、接口速率为1000Mbps，并开启DLDP功能。

[DeviceA] interface gigabitethernet 1/0/2

[DeviceA-GigabitEthernet1/0/2] duplex full

[DeviceA-GigabitEthernet1/0/2] speed 1000

[DeviceA-GigabitEthernet1/0/2] dldp enable

[DeviceA-GigabitEthernet1/0/2] quit

# 配置DLDP发现单向链路后接口的关闭模式为混合模式。

[DeviceA] dldp unidirectional-shutdown hybrid

(2)       配置Device B

# 全局开启DLDP功能。

<DeviceB> system-view

[DeviceB] dldp global enable

# 在接口GigabitEthernet1/0/1上配置双工模式为全双工、接口速率为1000Mbps，并开启DLDP功能。

[DeviceB] interface gigabitethernet 1/0/1

[DeviceB-GigabitEthernet1/0/1] duplex full

[DeviceB-GigabitEthernet1/0/1] speed 1000

[DeviceB-GigabitEthernet1/0/1] dldp enable

[DeviceB-GigabitEthernet1/0/1] quit

# 在接口GigabitEthernet1/0/2上配置双工模式为全双工、接口速率为1000Mbps，并开启DLDP功能。

[DeviceB] interface gigabitethernet 1/0/2

[DeviceB-GigabitEthernet1/0/2] duplex full

[DeviceB-GigabitEthernet1/0/2] speed 1000

[DeviceB-GigabitEthernet1/0/2] dldp enable

[DeviceB-GigabitEthernet1/0/2] quit

# 配置DLDP发现单向链路后接口的关闭模式为混合模式。

[DeviceB] dldp unidirectional-shutdown hybrid

4. 验证配置

配置完成后，通过使用display dldp命令可以查看DLDP的全局配置信息和接口上的DLDP信息。例如：

# 查看Device A上DLDP的全局配置信息和所有接口上的DLDP信息。

[DeviceA] display dldp

 DLDP global status: Enabled

 DLDP advertisement interval: 5s

 DLDP authentication-mode: None

 DLDP unidirectional-shutdown mode: Hybrid

 DLDP delaydown-timer value: 1s

 Number of enabled ports: 2

Interface GigabitEthernet1/0/1

 DLDP port state: Bidirectional

 Number of the port’s neighbors: 1

  Neighbor MAC address: 0023-8956-3600

  Neighbor port index: 1

  Neighbor state: Confirmed

  Neighbor aged time: 11s

Interface GigabitEthernet1/0/2

 DLDP port state: Bidirectional

 Number of the port’s neighbors: 1

  Neighbor MAC address: 0023-8956-3600

  Neighbor port index: 2

  Neighbor state: Confirmed

  Neighbor aged time: 12s

以上信息表明，接口GigabitEthernet1/0/1和GigabitEthernet1/0/2上的DLDP接口状态均为Bidirectional，说明这两个接口所在的链路均处于双通状态。

# 在Device A上配置允许日志信息输出到当前终端，且输出的日志信息最低为6级。

[DeviceA] quit

<DeviceA> terminal monitor

<DeviceA> terminal logging level 6

此后某刻，Device A上输出了以下日志信息：

<DeviceA>%Jan  4 07:16:06:556 2011 DeviceA DLDP/5/DLDP_NEIGHBOR_AGED: A neighbor on interface

GigabitEthernet1/0/1 was deleted because the neighbor was aged. The neighbor"s system MAC is 0023-8956-3600, and the port index is 162.

%Jan  4 07:16:06:560 2011 DeviceA DLDP/5/DLDP_NEIGHBOR_AGED: A neighbor on interface

GigabitEthernet1/0/2 was deleted because the neighbor was aged. The neighbor"s system MAC is 0023-8956-3600, and the port index is 165.

%Jan  4 07:16:06:724 2011 DeviceA IFNET/3/PHY_UPDOWN: Physical state on the interface GigabitEthernet1/0/1 changed to down.

%Jan  4 07:16:06:730 2011 DeviceA IFNET/3/PHY_UPDOWN: Physical state on the interface GigabitEthernet1/0/2 changed to down.

%Jan  4 07:16:06:736 2011 DeviceA IFNET/5/LINK_UPDOWN: Line protocol state on the interface GigabitEthernet1/0/1 changed to down.

%Jan  4 07:16:06:738 2011 DeviceA IFNET/5/LINK_UPDOWN: Line protocol state on the interface GigabitEthernet1/0/2 changed to down.

%Jan  4 07:16:07:152 2011 DeviceA DLDP/3/DLDP_LINK_UNIDIRECTIONAL: DLDP detected a unidirectional link on interface GigabitEthernet1/0/1. DLDP automatically shut down the interface. Please manually bring up the interface.

%Jan  4 07:16:07:156 2011 DeviceA DLDP/3/DLDP_LINK_UNIDIRECTIONAL: DLDP detected a unidirectional link on interface GigabitEthernet1/0/2. DLDP automatically shut down the interface. Please manually bring up the interface.

以上信息表明，接口GigabitEthernet1/0/1和GigabitEthernet1/0/2的物理状态与链路状态都down了。网络管理员进行进一步检查：

# 查看Device A上DLDP的全局配置信息和所有接口上的DLDP信息。

<DeviceA> display dldp

 DLDP global status: Enabled

 DLDP advertisement interval: 5s

 DLDP authentication-mode: None

 DLDP unidirectional-shutdown mode: Hybrid

 DLDP delaydown-timer value: 1s

 Number of enabled ports: 2

Interface GigabitEthernet1/0/1

 DLDP port state: Inactive

 Number of the port"s neighbors: 0 (Maximum number ever detected: 1)

Interface GigabitEthernet1/0/2

 DLDP port state: Inactive

 Number of the port"s neighbors: 0 (Maximum number ever detected: 1)

以上信息表明，接口GigabitEthernet1/0/1和GigabitEthernet1/0/2上的DLDP接口状态均为Inactive，说明这两个接口所在的链路均处于去激活状态。

由此可知，DLDP在接口GigabitEthernet1/0/1和GigabitEthernet1/0/2上都检测到了单向链路，且自动关闭了这两个接口。

经检查，网络管理员发现Device B上连接DeviceA的两个端口上的发光光纤被错误的进行了交叉连接。然后，网络管理员将光纤重新进行正确连接，检查无误后，再将Device A的两个接口重新打开：

# 打开接口GigabitEthernet1/0/1。

<DeviceA> system-view

[DeviceA] interface gigabitethernet 1/0/1

[DeviceA-GigabitEthernet1/0/1] undo shutdown

Device A上随即输出以下日志信息：

[DeviceA-GigabitEthernet1/0/1]%Jan  4 07:33:26:574 2011 DeviceA IFNET/3/PHY_UPDOWN: Physical state on the interface GigabitEthernet1/0/1 changed to up.

%Jan  4 07:33:57:562 2011 DeviceA DLDP/6/DLDP_NEIGHBOR_CONFIRMED: A neighbor was confirmed on interface GigabitEthernet1/0/1. The neighbor"s system MAC is 0023-8956-3600, and the port index is 162.

%Jan  4 07:33:57:563 2011 DeviceA DLDP/6/DLDP_LINK_BIDIRECTIONAL: DLDP detected a bidirectional link on interface GigabitEthernet1/0/1.

%Jan  4 07:33:57:590 2011 DeviceA IFNET/5/LINK_UPDOWN: Line protocol state on the interface GigabitEthernet1/0/1 changed to up.

%Jan  4 07:33:57:609 2011 DeviceA STP/6/STP_DETECTED_TC: Instance 0"s port GigabitEthernet1/0/1 detected a topology change.

以上信息表明，接口GigabitEthernet1/0/1的物理状态和链路状态均已up，并确定了DLDP邻居，所在链路也变为双通状态。

# 打开接口GigabitEthernet1/0/2。

[DeviceA-GigabitEthernet1/0/2] quit

[DeviceA] interface GigabitEthernet1/0/2

[DeviceA-GigabitEthernet1/0/2] undo shutdown

Device A上随即输出以下日志信息：

[DeviceA-GigabitEthernet1/0/2]%Jan  4 07:35:26:574 2011 DeviceA IFNET/3/PHY_UPDOWN: Physical state on the interface GigabitEthernet1/0/2 changed to up.

%Jan  4 07:35:57:562 2011 DeviceA DLDP/6/DLDP_NEIGHBOR_CONFIRMED: A neighbor was confirmed on interface GigabitEthernet1/0/2. The neighbor"s system MAC is 0023-8956-3600, and the port index is 162.

%Jan  4 07:35:57:563 2011 DeviceA DLDP/6/DLDP_LINK_BIDIRECTIONAL: DLDP detected a bidirectional link on interface GigabitEthernet1/0/2.

%Jan  4 07:35:57:590 2011 DeviceA IFNET/5/LINK_UPDOWN: Line protocol state on the interface GigabitEthernet1/0/2 changed to up.

%Jan  4 07:35:57:609 2011 DeviceA STP/6/STP_DETECTED_TC: Instance 0"s port GigabitEthernet1/0/2 detected a topology change.

以上信息表明，接口GigabitEthernet1/0/2的物理状态和链路状态均已up，并确定了DLDP邻居，所在链路也变为双通状态。