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Troubleshooting Guide

CloudEngine 16800, 12800, 12800E, 8800, 7800, 6800, and 5800 Series Switches

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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).
OSPF Route Flapping Occurs

OSPF Route Flapping Occurs

Common Causes

This fault is commonly caused by the following:

  • An interface flaps.
  • A neighbor flaps.
  • Router IDs conflict.
  • IP addresses conflict.
  • External routes flap.

Troubleshooting Flowchart

If OSPF route flapping occurs, rectify the fault according to Figure 6-8.

Figure 6-8 Troubleshooting flowchart for OSPF route flapping

Troubleshooting Procedure

Procedure

  1. Check the cause of route flapping.

    Log in to the device that receives routes and run the display ospf spf-statistics verbose command in any view to check the cause of route recalculation.

    <HUAWEI> display ospf spf-statistics verbose
                    OSPF Process 1 with Router ID 192.168.2.200                                                                         
    Routing table change statistics:                                                                                                    
    Index: 1                                                                                                                            
                     Time     : 2015-07-15 11:48:46                                                                                     
                     Intra    : 2     Added,0     Deleted                                                                               
                     Inter    : 0     Added,0     Deleted                                                                               
                     External : 0     Added,0     Deleted                                                                               
                     The reason of calculation is:Topo                                                                                  
                     NO.             LS ID              Adv Router                                         
                     1     Router        192.168.3.200      192.168.3.200                                                               
    Index: 2                                                                                                                            
                     Time     : 2015-07-15 11:48:42                                                                                     
                     Intra    : 1     Added,0     Deleted                                                                               
                     Inter    : 0     Added,0     Deleted                                                                               
                     External : 0     Added,0     Deleted                                                                               
                     The reason of calculation is:Topo                                                                                  
                     NO.             LS ID              Adv Router                                         
                     1     Network       172.16.1.1         192.168.3.200  

    Check the Type field, which indicates the type of LSAs triggering route recalculation.

    • If the Type field displays Router, Router LSAs result in route flapping. Go to step 2.
    • If the Type field displays Network, Network LSAs result in route flapping. Go to step 4.
    • If the Type field displays Sum-Net, Sum-Net LSAs result in route flapping. Go to step 5.
    • If the Type field displays External or NSSA, External LSAs or NSSA LSAs result in route flapping. Go to step 6.

  2. Router LSAs result in route flapping.

    • If the Adv Router field in 1 displays the local device's router ID, Router LSAs are generated by this device. Rectify the fault according to the following procedure.

      • Run the display interface command in any view to check whether an interface flaps according to the Last physical up time and Last physical down time fields. The two fields indicate the time when an interface becomes Up and Down for the last time. If an interface flaps, check whether the device's link is faulty.

        <HUAWEI> display interface 10GE3/0/15
        10GE3/0/15 current state : UP (ifindex: 1760)                                                                                       
        Line protocol current state : UP                                                                                                    
        Description:                                                                                                                        
        Switch Port, PVID :    1, TPID : 8100(Hex), The Maximum Frame Length is 9216                                                        
        Internet protocol processing : disabled                                                                                             
        IP Sending Frames' Format is PKTFMT_ETHNT_2, Hardware address is e468-a3f9-2101                                                     
        Port Mode:  COMMON COPPER,     Port Split:                         -                                                                
        Speed:              10000,     Loopback:                        NONE                                                                
        Duplex:              FULL,     Negotiation:                  DISABLE                                                                
        Input Flow-control: DISABLE,     Output Flow-control:          DISABLE          
        Mdi:                      -,     Fec:                                -
           : 2015-07-15 12:11:35                                               
         : 2015-07-15 11:53:05                                                               
        Current system time: 2015-07-15 15:02:43                                                                                            
        ...
      • If no interface flaps, run the display ospf peer last-nbr-down command in any view to check whether a neighbor flaps. If so, rectify the fault according to OSPF Neighbor Flapping Occurs.

        <HUAWEI> display ospf peer last-nbr-down 
        OSPF Process 1 with Router ID 192.168.2.200                                                                                         
                                                                                                                                            
                                 Last Down OSPF Peer                                                                                        
                                                                                                                                            
                 Neighbor Ip Address : 10.0.0.1                                                                                             
                 Neighbor Area   Id  : 0.0.0.0                                                                                              
                 Neighbor Router Id  : 10.1.1.3                                                                                              
                 Interface           : Vlanif4000 (1803)                                                                                    
                 Immediate Reason    : Neighbor Down Due to Kill Neighbor                                                                   
                 Primary Reason      : Link Fault or Interface Configuration Change                                                         
                 Down Time           : 2015-07-15 11:44:02                                                                                  
                                                                                                                                            
                 Neighbor Ip Address : 10.7.1.1                                                                                             
                 Neighbor Area   Id  : 0.0.0.0                                                                                              
                 Neighbor Router Id  : 10.90.255.254                                                                                        
                 Interface           : 10GE3/0/17 (1762)                                                                                    
                 Immediate Reason    : Neighbor Down Due to Kill Neighbor                                                                   
                 Primary Reason      : Link Fault or Interface Configuration Change                                                         
                 Down Time           : 2015-07-14 19:42:14                                                                                  
                                                                                                                                            
                 Neighbor Ip Address : 10.0.0.1                                                                                             
                 Neighbor Area   Id  : 0.0.0.0                                                                                              
                 Neighbor Router Id  : 10.1.1.3                                                                                              
                 Interface           : Vlanif4000 (1803)                                                                                    
                 Immediate Reason    : Neighbor Down Due to Kill Neighbor                                                                   
                 Primary Reason      : Link Fault or Interface Configuration Change                                                         
                 Down Time           : 2015-07-10 17:17:39    
        

      If the preceding steps cannot locate the cause of route flapping, check whether router IDs conflict. Run the display ospf lsdb router self-originate command in any view multiple times to check Router LSAs. If the seq field keeps increasing and the Ls age field remains a small value, the Router LSA keeps being refreshed. When this occurs, router IDs conflict in an OSPF area.

      <HUAWEI> display ospf lsdb router self-originate
      OSPF Process 1 with Router ID 192.168.2.200                                                                                         
      Area: 0.0.0.0                                                                                                                       
      ----------------------------------------------------------------------------                                                        
                                                                                                                                          
        Type      : Router                                                                                                                
        Ls id     : 192.168.2.200                                                                                                         
        Adv rtr   : 192.168.2.200                                                                                                         
        Ls age    : 1020                                                                                                                  
        Len       : 72                                                                                                                    
        Options   :  E                                                                                                                    
        seq#      : 80000247                                                                                                              
        chksum    : 0x4d35                                                                                                                
        Link count: 4                                                                                                                     
           Link ID: 192.168.2.200                                                                                                         
           Data   : 255.255.255.255                                                                                                       
           Link Type: StubNet                                                                                                             
           Metric : 0                                                                                                                     
           Link ID: 10.7.1.0                                                                                                              
           Data   : 255.255.255.0                                                                                                         
           Link Type: StubNet                                                                                                             
           Metric : 1                                                                                                                     
           Link ID: 10.0.0.2                                                                                                              
           Data   : 10.0.0.2                                                                                                              
           Link Type: TransNet                                                                                                            
           Metric : 1                                                                                                                     
           Link ID: 10.1.1.60                                                                                                              
           Data   : 255.255.255.255                                                                                                       
           Link Type: StubNet                                                                                                             
           Metric : 0  
      

      Check the interface's IP address in the Router LSA to locate the device with a conflicting router ID. Rectify the router ID conflict in the area according to 3.

    • If the Adv Router field in 1 does not display the local device's router ID, the router LSA is not generated by this device. Rectify the fault according to the following procedure.
      • Run the display ospf lsdb router link-state-id command in any view of the local device multiple times to check the Router LSA of the device. link-state-id specifies the LS ID in 1. If the seq# field keeps increasing and the Ls age field remains a small value, the LSA keeps being refreshed. Observe the Link ID field of the LSA.
        1. If the Link ID field keeps changing, the related device's interface or neighbor flaps frequently. To get information about the relationships between the Link ID and interface IP addresses, see 3. After finding the flapping interface, log in to the device identified by the Adv rtr field to check the interface or neighbor specified by the Link ID field flaps or send related logs to technical support personnel for further analysis.
        2. If the Link ID field remains unchanged or shows different values in command outputs, router IDs conflict in the area. See 3 to rectify the fault.

  3. Rectify a router ID conflict in an area.

    Check the device's logs to confirm whether a Router ID conflict has occurred. A router ID conflict trap will be generated when router ID conflicts are detected for a specified number of times.

    OSPF_1.3.6.1.4.1.2011.5.25.155.31.3 hwOspfv2IntraAreaRouteridConflict
    in an intra area. (ProcessId=[ProcessId], AreaId=[AreaId], SelfIfnetIndex=[SelfIfnetIndex], NbrIpAddr=[NbrIpAddr], RouterId=[RouterId], NbrRtrId=[NbrRtrId])

    Generally, an OSPF router ID conflict in an area can be solved automatically because a new Router ID will be elected within a specified period. However, it may take a long period for such a conflict to be solved automatically. You can locate the device with a conflicting router ID and solve the conflict manually according to the following procedure:

    If you check the Router LSA of the local device and find a router ID conflict, log in to other devices in the area to locate the device with the conflicting router ID because the local device displays only its Router LSA.

    1. Run the display ospf lsdb router link-state-id command in any view continuously to observe the Link ID field of the Router LSA. link-state-id specifies the LS ID in 1, and the Link ID field indicates the set of interfaces that connect the LSA generator to the area.
      <HUAWEI> display ospf lsdb router 10.1.1.3
      
                OSPF Process 1 with Router ID 192.168.2.200                                                                                         
      Area: 0.0.0.0                                                                                                                       
      ----------------------------------------------------------------------------                                                        
                                                                                                                                          
        Type      : Router                                                                                                                
        Ls id     : 10.1.1.3                                                                                                               
        Adv rtr   : 10.1.1.3                                                                                                               
        Ls age    : 1162                                                                                                                  
        Len       : 60                                                                                                                    
        Options   :  ABR  E                                                                                                               
        seq#      : 80000157                                                                                                              
        chksum    : 0x4011                                                                                                                
        Link count: 3                                                                                                                     
           Link ID: 10.0.0.2                                                                                                              
           Data   : 10.0.0.1                                                                                                              
           : TransNet                                                                                  
           Metric : 1                                                                                                                     
           Link ID: 10.1.1.127                                                                                                             
           Data   : 255.255.255.255                                                                                                       
           Link Type: StubNet                                                                                                             
           Metric : 0                                                                                                                     
           Link ID: 10.6.1.1                                                                                                              
           Data   : 10.6.1.2                                                                                                              
           Link Type: TransNet                                                                                                            
           Metric : 1          
      • If the Link Type field displays P2P, the Data field indicates the IP address of the P2P interface that connects the device to the current area.
      • If the Link Type field displays TransNet, the Data field indicates the IP address of the broadcast interface that connects the device to the current area.
      • If the Link Type field displays StubNet and the Data field displays 255.255.255.255, the Data field indicates a loopback interface. The Link ID field indicates the loopback interface's IP address of the device.

      If the Link ID field displays different values, one of which indicates the Router LSA of the device with a conflict router ID, find the device's interface IP address or loopback interface IP address and then locate the device according to the preceding procedure.

    2. In most situations, LSAs are refreshed fast when a router ID conflict occurs. Therefore, the device with the conflicting router ID cannot be found according to the preceding procedure. To find such a device, run the display ospf brief command in any view of each device in the area and check the router ID of each process. Solve the router ID conflict according to the following procedure.
      <HUAWEI> display ospf brief
      OSPF Process 1 with Router ID 192.168.2.200                                                                                        
                                                                                                                                          
       RouterID: 192.168.2.200          Border Router:                                                                                    
       Multiple VPN instance is not enabled                                                                                               
       Global DS-TE Mode is disabled                                                                                                      
       Graceful-restart capability is disabled                                                                                            
       Helper support capability is not configured                                                                                        
       SPF schedule interval        : Max 10000ms, Start 500ms, Hold 1000ms                                                               
       Default ASE parameters       : Metric: 1 Tag: 1 Type: 2                                                                            
       Route preference             : 10                                                                                                  
       ASE route preference         : 150                                                                                                 
       Intra route preference       : 10                                                                                                  
       Inter route preference       : 10                                                                                                  
       SPF computation count        : 32                                                                                                  
       RFC 1583 compatible                                                                                                                
       Retransmission limitation is disabled                                                                                              
       BFD enabled                                                                                                                        
       BFD Timers: Tx-Interval 50, Rx-Interval 50, Multiplier 3                                                                           
       Area count                   : 1                                                                                                   
       Nssa area count              : 0                                                                                                   
       Exchange/Loading neighbors   : 0  
      ...
      

      Run the ospf router-id router-id command in the system view to configure a new router ID and restart the OSPF process to make the router ID take effect. router-id specifies a new router ID.

  4. Network LSAs result in route flapping.

    1. If the Adv Router field in 1 displays the router ID of the local device, Network LSAs are generated by this device. Rectify the fault according to the following procedure.

      Run the display ospf peer last-nbr-down command in any view to check whether a neighbor flaps.

      • If a neighbor flaps, rectify the fault according to 6.8.2-OSPF Neighbor Flapping Occurs.
      • If no neighbor flaps, an IP address conflict may have occurred in the area. Run the display ospf lsdb network command in any view to check a Network LSA. If the seq# field keeps increasing and the Ls age field remains a small value, the Network LSA keeps being refreshed. In this situation, an IP address conflict exists in the area.
        <HUAWEI> display ospf lsdb network 10.0.0.2
        OSPF Process 1 with Router ID 192.168.2.200                                                                                         
        Area: 0.0.0.0                                                                                                                       
        ----------------------------------------------------------------------------                                                        
                                                                                                                                            
          Type      : Network                                                                                                               
          Ls id     : 10.0.0.2                                                                                                              
          Adv rtr   : 192.168.2.200                                                                                                         
          Ls age    : 1507                                                                                                                  
          Len       : 32                                                                                                                    
          Options   :  E                                                                                                                    
          seq#      : 800001b9                                                                                                              
          chksum    : 0xa264                                                                                                                
          Net mask  : 255.255.255.0                                                                                                         
             Attached Router: 10.1.1.3                                                                                                       
             Attached Router: 192.168.2.200   
        

        Find the device with a conflicting IP address using the following methods:

        1. Log in to a non-DR device on the same network segment and in the same area as the local device. Use the tracert command to trace the conflicting IP address from the non-DR device, check whether different paths are displayed. If different paths are displayed, find the device with a conflicting IP address.
        2. On the local device, check all Router LSAs in the area and find the interface with a conflicting IP address according to 2.
        3. Check the configurations of the area to find the device with a conflicting IP address.

        After finding the conflicting IP address, specify a new IP address according to network planning.

    2. If the Adv Router field in 1 does not display the router ID of the local device, the Network LSA is not generated by this device. Run the display ospf lsdb network command continuously to check a Network LSA. If an IP address conflict occurs, rectify the fault according to the preceding procedure.
    3. If the cause of the route flapping cannot be located, log in to the device identified by the Adv rtr field and perform this operation again or send related logs to technical support personnel for further analysis.

  5. Sum-Net LSAs result in route flapping.

    If the Type field in 1 displays Sum-Net, route flapping occurs in another OSPF area. Rectify the fault according to the following procedure.

    Run the display ospf lsdb summary command continuously to check which prefixes of Summary LSAs change.

    <HUAWEI> display ospf lsdb summary
    OSPF Process 1 with Router ID 192.168.2.200                                                                                         
    Area: 0.0.0.0                                                                                                                       
    ----------------------------------------------------------------------------                                                        
                                                                                                                                        
      Type      : Sum-Net                                                                                                               
      Ls id     : 10.1.1.0                                                                                                             
      Adv rtr   : 10.1.1.3                                                                                                               
      Ls age    : 1547                                                                                                                  
      Len       : 28                                                                                                                    
      Options   :  E                                                                                                                    
      seq#      : 80000067                                                                                                              
      chksum    : 0x8294                                                                                                                
      Net mask  : 255.255.255.0                                                                                                         
      Tos 0  metric: 1                                                                                                                  
                                                                                                                                        
      Type      : Sum-Net                                                                                                               
      Ls id     : 10.1.1.0                                                                                                             
      Adv rtr   : 10.1.1.3                                                                                                               
      Ls age    : 1547                                                                                                                  
      Len       : 28                                                                                                                    
      Options   :  E                                                                                                                    
      seq#      : 80000067                                                                                                              
      chksum    : 0x68ac                                                                                                                
      Net mask  : 255.255.255.0                                                                                                         
      Tos 0  metric: 1                                               
    

    Log in to the ABR identified by the Adv rtr field and run the display ospf routing command to check which area routes are learned from and locate routing flapping in this area according to the preceding procedures.

    <HUAWEI> display ospf routing 10.1.1.1
    
                                                                                                                                        
              OSPF Process 1 with Router ID 192.168.80.182                                                                              
                                                                                                                                        
     Destination    : 10.1.1.1/32                                                                                                       
     AdverRouter    : 192.168.80.182           Area                : 0.0.0.0                                                            
     Cost           : 0                        Type                : Direct                                                             
     NextHop        : 10.1.1.1                 Interface           : Loop0                                                              
     Priority       : Medium                   Age                 : 16h03m05s                                                          

  6. External LSAs or NSSA LSAs result in route flapping.

    If the Type field in 1 displays External or NSSA, rectify the fault according to the following procedure. The following procedure describes how to solve the route flapping caused by External LSAs. This fault location procedure for NSSA LSAs is similar.

    1. A common cause of this fault is that external routes change. If you log in to the ASBR identified by the Adv rtr field, you will see that routes of other routing protocols are flapping. Rectify the fault according to the troubleshooting procedures of these routing protocols.
    2. Another cause of the fault is that routing protocols import routes from each other but the route priorities are configured incorrectly. For example, two OSPF-enabled routers import static routes, and a low priority is configured for static routes. One router also receives OSPF routes from the other router and replaces low-priority static routes in the IP routing table with these OSPF routes. Consequently, static routes disappear from the IP routing table and the OSPF routes also disappear because their dependent routes (static routes) disappear. Static routes then become active and replace the OSPF routes in the IP routing table. This process repeats. To rectify the fault, configure a correct priority for routes according to network planning.
    3. If external routes do not change, check whether interface or neighbor flapping occurs on the ASBR according to the preceding procedures.
    4. If the cause of route flapping cannot be located, a router ID conflict may exist. Run the display ospf lsdb ase command in any view continuously to check External LSAs. If External LSAs remain unchanged, the seq# field keeps increasing and the Ls age field remains a small value, a router ID conflict exists in the current AS. To rectify the fault, find the device with the conflicting router ID and assign a new router ID to the device according to network planning.
      <HUAWEI> display ospf lsdb ase                                                                                                                                    
      OSPF Process 1 with Router ID 192.168.2.200                                                                                         
      Area: 0.0.0.0                                                                                                                       
      ----------------------------------------------------------------------------                                                        
                                                                                                                                          
        Type      : Sum-Net                                                                                                               
        Ls id     : 10.1.1.0                                                                                                             
        Adv rtr   : 10.1.1.3                                                                                                               
        Ls age    : 1547                                                                                                                  
        Len       : 28                                                                                                                    
        Options   :  E                                                                                                                    
        seq#      : 80000067                                                                                                              
        chksum    : 0x8294                                                                                                                
        Net mask  : 255.255.255.0                                                                                                         
        Tos 0  metric: 1                                                                                                                  
                                                                                                                                          
        Type      : Sum-Net                                                                                                               
        Ls id     : 10.1.2.0                                                                                                             
        Adv rtr   : 10.1.1.3                                                                                                               
        Ls age    : 1547                                                                                                                  
        Len       : 28                                                                                                                    
        Options   :  E                                                                                                                    
        seq#      : 80000067                                                                                                              
        chksum    : 0x68ac                                                                                                                
        Net mask  : 255.255.255.0                                                                                                         
        Tos 0  metric: 1                                                                                                                  
      

  7. Collect the following information and contact technical support personnel.

    • Results of the preceding troubleshooting procedure
    • Configuration file, logs, and alarms of the device

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Updated: 2020-01-07

Document ID: EDOC1000060766

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