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AR Router Troubleshooting Guide

This Product Documentation provides guidance for maintaining AR Enterprise Router, covering common information collection and fault diagnostic commands, typical fault troubleshooting guide, and troubleshooting.
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Huawei uses machine translation combined with human proofreading to translate this document to different languages in order to help you better understand the content of this document. Note: Even the most advanced machine translation cannot match the quality of professional translators. Huawei shall not bear any responsibility for translation accuracy and it is recommended that you refer to the English document (a link for which has been provided).
The OSPF Neighbor Relationship Is Down

The OSPF Neighbor Relationship Is Down

Common Causes

This fault is commonly caused by one of the following:

  • The BFD is faulty.
  • The other device is faulty.
  • CPU usage on the main control board or interface board of the faulty device is too high.
  • The link is faulty.
  • The interface is not Up.
  • The IP addresses of the two devices on both ends of the link are on different network segments.
  • The router IDs of the two devices conflict.
  • The area types of the two devices are inconsistent.
  • The parameter settings of the two devices are inconsistent.

Troubleshooting Flowchart

After OSPF is configured on the network, it is found that the OSPF neighbor relationship is Down. Figure 19-3 shows the troubleshooting flowchart.

Figure 19-3  Troubleshooting flowchart for the fault that the OSPF neighbor relationship is Down

Troubleshooting Procedure

Context

NOTE:

Saving the results of each troubleshooting step is recommended. If you are unable to correct the fault, you will have a record of your actions to provide Huawei technical support personnel.

Procedure

  1. Check logs to find the cause of the fault.

    Run the display logbuffer command, and you can find the following log information:
    NBR_DOWN_REASON(l): Neighbor state leaves full or changed to Down. (ProcessId=[USHORT], NeighborRouterId=[IPADDR], NeighborAreaId=[ULONG],  NeighborInterface=[STRING],NeighborDownImmediate reason=[STRING], NeighborDownPrimeReason=[STRING], NeighborChangeTime=[STRING])

    Check the NeighborDownImmediate reason field which records the cause of the fault. The possible causes of the fault are as follows:

    • Neighbor Down Due to Inactivity

      If a device does not receive a Hello packet from its neighbor within the timeout period, the OSPF neighbor relationship goes Down. In this case, go to Step 2.

    • Neighbor Down Due to Kill Neighbor

      If the interface is Down, BFD is Down, or the reset ospf process command is run, the OSPF neighbor relationship goes Down. In this case, check the NeighborDownPrimeReason field to determine the specific cause of the fault.

      • If the value of the NeighborDownPrimeReason field is Physical Interface State Change, it indicates that the interface status has changed. In this case, run the display interface [ interface-type [ interface-number ] ] command to check the interface status, and then troubleshoot the interface fault.
      • If the value of the NeighborDownPrimeReason field is BFD Session Down, it indicates that the BFD session status is Down. In this case, troubleshoot the BFD fault.
      • If the value of the NeighborDownPrimeReason field is OSPF Process Reset, it indicates that the reset ospf process command has been run. The OSPF process is restarting. Wait until OSPF re-establishes the OSPF neighbor relationship.
    • Neighbor Down Due to 1-Wayhello Received or Neighbor Down Due to SequenceNum Mismatch

      When the OSPF status on the remote device goes Down first, the remote device sends a 1-Way Hello packet to the local device, causing OSPF on the local device to go Down. In this case, troubleshoot the fault that caused OSPF on the remote device to go Down.

    • In other cases, go to Step 9.

  2. Check that the link between the two devices is normal.

  3. Check that the CPU usage is within the normal range.

    Run the display cpu-usage command to check whether the CPU usage of the faulty device is higher than 60%. If the CPU usage is too high, OSPF fails to normally send and receive protocol packets, causing the neighbor relationship to flap. In this case, go to Step 9. If the CPU usage is within the normal range, go to Step 4.

  4. Check that the interface status is Up.

    Run the display interface [ interface-type [ interface-number ] ] command to check the physical status of the interface. If the physical status of the interface is Down, troubleshoot the interface fault.

    If the physical status of the interface is Up, run the display ospf interface command to check whether the OSPF status of the interface is Down. The normal status is DR, BDR, DR Other, or P2P.

    <Huawei> display  ospf interface
                 OSPF Process 1 with Router ID 1.1.1.1
                         Interfaces
     Area: 0.0.0.0          
     IP Address      Type         State    Cost    Pri   DR              BDR
     192.168.1.1     Broadcast    DR       1       1     192.168.1.1     0.0.0.0
    

    • If the OSPF status of the interface is Down, run the display ospf cumulative command to check whether the number of interfaces with OSPF enabled in the OSPF process exceeds the upper threshold. If so, reduce the number of interfaces with OSPF enabled. For the details about upper threshold of the interfaces, see the /License file of the product.

      <Huawei> display ospf cumulative
                OSPF Process 1 with Router ID 1.1.1.1
                        Cumulations
        IO Statistics
                   Type        Input     Output
                  Hello            0         86
         DB Description            0          0
         Link-State Req            0          0
      Link-State Update            0          0
         Link-State Ack            0          0
        SendPacket Peak-Control: (Disabled)
        ASE: (Disabled)
        LSAs originated by this router
        Router: 1
        Network: 0
        Sum-Net: 0
        Sum-Asbr: 0
        External: 0
        NSSA: 0
        Opq-Link: 0
        Opq-Area: 0
        Opq-As: 0
        LSAs Originated: 1  LSAs Received: 0
        Routing Table:
          Intra Area: 1  Inter Area: 0  ASE: 0
        Up Interface Cumulate: 1
      
    • If the OSPF status of the interface is not Down, go to Step 5.

  5. If the interface is connected to a broadcast network or an NBMA network, ensure that the IP addresses of the two devices are on the same network segment.
    • If the IP addresses of the two devices are on different network segments, modify the IP addresses of the devices to ensure that the IP addresses are on the same network segment.

    • If the IP addresses of the two devices are on the same network segment, go to 6.

  6. Check that the MTUs of the interfaces on both ends are consistent.

    If the ospf mtu-enable command is run on interfaces on both ends, the MTUs of the two interfaces must be consistent. If the MTUs are inconsistent, the OSPF neighbor relationship cannot be established.

    • If the MTUs of the two interfaces are inconsistent, run the mtu mtu command in the interface view to change the MTUs of the two interfaces to be consistent.

    • If the MTUs of the two interfaces are consistent, go to Step 7.

  7. Check whether there is an interface with a priority that is not 0.

    On broadcast and NBMA network segments, there must be at least one interface with a priority that is not 0 to ensure that the DR can be correctly elected. Otherwise, the OSPF neighbor relationship can only reach the two-way state.

    Run the display ospf interface command to view the interface priority.

    <Huawei> display ospf interface
             OSPF Process 100 with Router ID 1.1.1.1 
                     Interfaces 
     Area: 0.0.0.0           
     IP Address      Type         State    Cost  Pri   DR              BDR 
     1.1.1.1         Broadcast    DR       1      1    1.1.1.1         0.0.0.0

  8. Ensure that the OSPF configurations on the two devices are correct.

    1. Check whether the OSPF router IDs of the two devices are the same.

      <Huawei> display ospf brief
                OSPF Process 1 with Router ID 1.1.1.1
                        OSPF Protocol Information
      

      If the IDs are the same, run the ospf router-idrouter-id command to modify the OSPF router IDs of the two devices. The router ID of each device should be unique within an AS. If the router IDs are not the same, proceed with this step.

    2. Check whether the OSPF Area ID configurations on the two devices are consistent.

      <Huawei> display ospf interface
                OSPF Process 1 with Router ID 10.1.1.1
                        Interfaces
       Area: 0.0.0.0          
       IP Address      Type         State    Cost  Pri   DR              BDR
       10.1.1.1        Broadcast    BDR      1     1     10.1.1.2        10.1.1.1
      

      If the OSPF Area ID configurations on the two devices are inconsistent, modify the OSPF Area ID. If they are consistent, proceed with this step.

    3. Check whether other OSPF configurations on the two devices are consistent.

      Run the display ospf error command every 10s for 5 m.

      <Huawei> display ospf error
                OSPF Process 1 with Router ID 10.1.1.1
                        OSPF error statistics
      
      General packet errors:
       0     : IP: received my own packet     0     : Bad packet
       0     : Bad version                    0     : Bad checksum
       0     : Bad area id                    0     : Drop on unnumbered interface
       1     : Bad virtual link               0     : Bad authentication type
       0     : Bad authentication key         0     : Packet too small
       0     : Packet size > ip length        0     : Transmit error
       0     : Interface down                 0     : Unknown neighbor
       0     : Bad net segment                0     : Extern option mismatch
       0     : Router id confusion                0     : Bad authentication sequence number
      
      
      HELLO packet errors:
       0     : Netmask mismatch               0     : Hello timer mismatch
       0     : Dead timer mismatch            0     : Virtual neighbor unknown
       0     : NBMA neighbor unknown          0     : Invalid Source Address
      
      DD packet errors:
       0     : Neighbor state low             0     : Unknown LSA type
       0     : MTU option mismatch
      
      LS ACK packet errors:
       0     : Neighbor state low             0     : Unknown LSA type
      
      LS REQ packet errors:
       0     : Neighbor state low             0     : Empty request
       0     : Bad request
      
      LS UPD packet errors:
       0     : Neighbor state low             0     : Newer self-generate LSA
       0     : LSA checksum bad               0     : Received less recent LSA
       0     : Unknown LSA type
      
      Opaque errors:
       0     : 9-out of flooding scope        0     : 10-out of flooding scope
       0     : 11-out of flooding scope       0     : Unknown TLV type
      
      Retransmission for packet over Limitation errors:
       0     : Number for DD Packet           0     : Number for Update Packet
       0     : Number for Request Packet
      
      Receive Grace LSA errors:
       0     : Number of invalid LSAs         0     : Number of policy failed LSAs
       0     : Number of wrong period LSAs
      
      Configuration errors:
      0     : Tunnel cost mistake
      • Check the Bad authentication type field. If the value of this field keeps increasing, the OSPF authentication types of the two devices that establish the neighbor relationship are inconsistent. In this case, run the area-authentication-mode command to configure the same authentication type for the two devices.
      • Check the Hello timer mismatch field. If the value of this field keeps increasing, the value of the Hello timers on the two devices that establish the neighbor relationship are inconsistent. In this case, check the interface configurations of the two devices and run the ospf timer hello command to set the same value for the Hello timers.
      • Check the Dead timer mismatch field. If the value of this field keeps increasing, the values of the dead timers on the two devices that establish the neighbor relationship are inconsistent. In this case, check the interface configurations of the two devices and run the ospf timer dead command to set the same value for the dead timers.

    If the fault persists, go to Step 9.

  9. Step 9 Contact contact technical support personnel and provide them with the following information.

    • Results of the preceding troubleshooting procedure
    • Configuration files, log files, and alarm files of the devices

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Updated: 2019-05-10

Document ID: EDOC1000079719

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