Hi there, everyone!
This post is about the issue that the AR OSPF neighbor relationship is down. Please see more details as you read further down this post.
1.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 contro board or interface board of the faulty device is too high.
The ink is faulty.
The interface is not Up.
The IP addresses of the two devices on both ends of the ink are on different network segments.
The router IDs of the two devices confict.
The area types of the two devices are inconsistent.
The parameter settings of the two devices are inconsistent.
2.Troubleshooting Flowchart
After OSPF is configured on the network, it is found that the OSPF neighbor relationship is Down. Figure 1-1 shows the Troubleshooting Flowchart.
Figure 1-1 Troubleshooting Flowchart for the fault that the OSPF neighbor relationship is Down
3.Troubleshooting Procedure
Context
Saving the results of each Troubleshooting step is recommended. If you are unable to correct the fault, you wi have a record of your actions to provide Huawei technical support personnel.
Procedure
Step 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(): Neighbor state eaves fu or changed to Down. (ProcessId=[USHORT], NeighborRouterId=[IPADDR], NeighborAreaId=[UONG], 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 Heo 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 Ki 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 reationship.
Neighbor Down Due to 1-Wayheo 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 Heo packet to the oca device, causing OSPF on the oca 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.
Step 2 Check that the link between the two devices is normal.
Step 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 fap. In this case, go to Step 9. If the CPU usage is within the normal range, go to Step 4.
Step 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 cumuative command to check whether the number of interfaces with OSPF enabed in the OSPF process exceeds the upper threshod. If so, reduce the number of interfaces with OSPF enabed. For the detais about upper threshod of the interfaces, see the /icense fie of the product.
<Huawei> display ospf cumuative
OSPF Process 1 with Router ID 1.1.1.1
Cumuations
IO Statistics
Type Input Output
Heo 0 86
DB Description 0 0
ink-State Req 0 0
ink-State Update 0 0
ink-State Ack 0 0
SendPacket Peak-Contro: (Disabed)
ASE: (Disabed)
SAs originated by this router
Router: 1
Network: 0
Sum-Net: 0
Sum-Asbr: 0
Externa: 0
NSSA: 0
Opq-ink: 0
Opq-Area: 0
Opq-As: 0
SAs Originated: 1 SAs Received: 0
Routing Tabe:
Intra Area: 1 Inter Area: 0 ASE: 0
Up Interface Cumuate: 1
If the OSPF status of the interface is not Down, go to Step 5.
Step 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 Step 6.
Step 6 Check that the MTUs of the interfaces on both ends are consistent.
If the ospf mtu-enabe 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.
Step 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 ony 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
Step 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 Protoco Information
If the IDs are the same, run the ospf router-id router-id command to modify the OSPF router IDs of the two devices. The router ID of each device shoud 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
Genera 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 virtua ink 0 : Bad authentication type
0 : Bad authentication key 0 : Packet too sma
0 : Packet size > ip ength 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
HEO packet errors:
0 : Netmask mismatch 0 : Heo timer mismatch
0 : Dead timer mismatch 0 : Virtua neighbor unknown
0 : NBMA neighbor unknown 0 : Invaid Source Address
DD packet errors:
0 : Neighbor state ow 0 : Unknown SA type
0 : MTU option mismatch
S ACK packet errors:
0 : Neighbor state ow 0 : Unknown SA type
S REQ packet errors:
0 : Neighbor state ow 0 : Empty request
0 : Bad request
S UPD packet errors:
0 : Neighbor state ow 0 : Newer sef-generate SA
0 : SA checksum bad 0 : Received ess recent SA
0 : Unknown SA type
Opaque errors:
0 : 9-out of fooding scope 0 : 10-out of fooding scope
0 : 11-out of fooding scope 0 : Unknown TV type
Retransmission for packet over imitation errors:
0 : Number for DD Packet 0 : Number for Update Packet
0 : Number for Request Packet
Receive Grace SA errors:
0 : Number of invaid SAs 0 : Number of poicy faied SAs
0 : Number of wrong period SAs
Configuration errors:
0 : Tunne 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 Heo timer mismatch fied. If the value of this field keeps increasing, the value of the Heo 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 heo command to set the same value for the Heo 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.
Step 9 Contact contact technical support personnel and provide them with the following information.
Results of the preceding Troubleshooting procedure
Configuration fies, og fies, and aarm fies of the devices
----End
4.Reevant Aarms and logs
Reevant Aarms
OSPF_1.3.6.1.2.1.14.16.2.2 ospfNbrStateChange
Reevant logs
OSPF/4/NBR_DOWN_REASON
