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E5000E OSPF Neighbor Fails to Be Established Because of the Link Problem

Publication Date:  2012-07-27 Views:  85 Downloads:  0
Issue Description
NE5000E�non-Huawei device
The NE5000E OSPF neighbor fails to be established. Its status is Exchange.

Area interface’s neighbors
Router ID: Address: GR State: Normal
State: Exchange Mode:Nbr is Master Priority: 1
DR: None BDR: None MTU: 4470
Dead timer due in 38 sec
Neighbor is up for 00:00:00
Authentication Sequence: [ 0 ] 
Alarm Information
Handling Process
1. Check the configuration to ensure that the configurations are correct.
2. Check if OSPF parameters are configured correctly on the interface.
3. Debug non-Huawei devices and find that the problem is caused by the failure of MTU negotiation. The value of the MTU at the two ends of the NE5000E is 4470, but the value of the MTU received by non-Huawei devices is 0, which means that non-Huawei devices do not receive the MTU value from the peer device. It is concluded that the link is not connected properly.
Ping the directly connected interface of the peer device from the NE5000E, and find that packet loss occurs.
PING 56 data bytes, press CTRL_C to break
Request time out
Reply from bytes=56 Sequence=2 ttl=255 time=5 ms
Reply from bytes=56 Sequence=3 ttl=255 time=5 ms
Reply from bytes=56 Sequence=4 ttl=255 time=5 ms
Request time out
40.00% packet loss
Ensure through the transport side that the link has no problem.
Perform traffic statistics on the NE5000E, and find that packets do not arrive at the interface of the NE5000E, which means that packets may be lost on the peer device or in the link.
Through the traffic statistics on the peer device, it is confirmed that the problem is caused by the board of non-Huawei devices.
The fault is rectified after the board is changed. 
Root Cause
1. The configuration problem
2. The parameter problem
3. The device problem 
There are multiple causes for the failure to receive OSPF packets. Enable OSPF debugging to check whether the link is reachable. The errors of an OSPF process can be displayed by the disp ospf error command or debug commands, such as the debug ospf packet command and the debug ospf event command.
If the OSPF process is normal, run the debug ip packet command to check whether the packet is forwarded successfully on the IP layer.