Automatically shutting down unidirectional links

As shown in Figure 10, Device A and Device B are connected through two fiber pairs.

Configure DLDP to automatically shut down the faulty port upon detecting a unidirectional link, and automatically bring up the port after you clear the fault.

1. Configure Device A:

   # Enable DLDP globally.

   <DeviceA> system-view
   [DeviceA] dldp global enable
   

   # Configure GigabitEthernet 1/0/1 to operate in full duplex mode and at 1000 Mbps, and enable DLDP on the port.

   [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
   

   # Configure GigabitEthernet 1/0/2 to operate in full duplex mode and at 1000 Mbps, and enable DLDP on the port.

   [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
   

   # Set the port shutdown mode to auto.

   [DeviceA] dldp unidirectional-shutdown auto
   

2. Configure Device B:

   # Enable DLDP globally.

   <DeviceB> system-view
   [DeviceB] dldp global enable
   

   # Configure GigabitEthernet 1/0/1 to operate in full duplex mode and at 1000 Mbps, and enable DLDP on it.

   [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
   

   # Configure GigabitEthernet 1/0/2 to operate in full duplex mode and at 1000 Mbps, and enable DLDP on it.

   [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
   

   # Set the port shutdown mode to auto.

   [DeviceB] dldp unidirectional-shutdown auto
   

3. Verify the configuration:

   # Display the DLDP configuration globally and on all the DLDP-enabled ports of Device A.

   [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
   

   The output shows that both GigabitEthernet 1/0/1 and GigabitEthernet 1/0/2 are bidirectional.

   # Enable the monitoring of logs on the current terminal on Device A. Set the lowest level of the logs that can be output to the current terminal to 6.

   [DeviceA] quit
   <DeviceA> terminal monitor
   <DeviceA> terminal logging level 6
   

   The following log information is displayed on Device A:

   <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.
   

   The output shows the following:

   • The port status of both GigabitEthernet 1/0/1 and GigabitEthernet 1/0/2 is down and then up.

   • The link status of both GigabitEthernet 1/0/1 and GigabitEthernet 1/0/2 is always down.

   # Display the DLDP configuration globally and of all the DLDP-enabled ports.

   <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)
   

   The output shows that the DLDP port status of both GigabitEthernet 1/0/1 and GigabitEthernet 1/0/2 is unidirectional. DLDP detects unidirectional links on them and automatically shuts down the two ports.

   The unidirectional links are caused by cross-connected fibers. Correct the fiber connections. As a result, the ports shut down by DLDP automatically recover, and Device A displays the following log information:

   <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.
   

   The output shows that the port status and link status of both GigabitEthernet 1/0/1 and GigabitEthernet 1/0/2 are now up and their DLDP neighbors are determined.