User receives the OSPF-4-NONEIGHBOR error message and database description from an unknown neighbor

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Wed, 07/22/2009 - 19:33
Jun 22nd, 2009
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Core Issue

The received error is a transient, or self-correcting, error message. The cause consists of flapping links, a change in the router ID of the neighboring router, or missed Database (DB)   packets. This means that the router received a DB packet from a neighbor that was considered dead for one of the same reasons (flapping links, a change in the router ID of the neighboring router, or missed DB packets).

To find out the cause of the error, issue the log-neighbor-changes command under Open Shortest Path First (OSPF). If the error message occurs on an infrequent basis (every few months), the cause is usually link congestion, or a link that went down.


The CPU utilization increased due to the shortest path first (SPF) algorithm being run again.


Resolution

Although it is unlikely that you will know when you missed a packet, or when your link flaps, the log-neighbor-changes command can help you know when this occurs. Once this is accomplished, you can compare it with the times of the error messages, and figure out the problem.

Configure the log-neighbor-changes command under OSPF. This helps you understand what is taking place between the neighbors.

If this is occurring every few months, it is probably due to link congestion, or a link that no longer connects. Check the underlying Layer 2 topology. If that does not help, collect data from the technical support, and open a TAC Service Request with the Cisco Technical Assistance Center (TAC).


OSPF Errors, Warnings, and Log Messages

Receiving "%ospf-4-NONEIGHBOR" error message

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