IP Routing

Troubleshooting OSPF

Document ID: 12151

Updated: Sep 15, 2008



This document provides troubleshooting information for common problems with Open Shortest Path First (OSPF). To see more infomation, or to go to the next flowchart, click the command boxes in red.



There are no specific requirements for this document.

Components Used

This document is not restricted to specific software and hardware versions.

The information in this document was created from the devices in a specific lab environment. All of the devices used in this document started with a cleared (default) configuration. If your network is live, make sure that you understand the potential impact of any command.


Refer to Cisco Technical Tips Conventions for more information on document conventions.

Main Flowchart

If you have the output of a show ip ospf neighbor, show ip ospf neighbor, or show tech-support command from your Cisco device, you can use Output Interpreter (registered customers only) to display potential issues and fixes. To use Output Interpreter, you must have JavaScript enabled.


Troubleshoot OSPF Neighbor States

Refer to OSPF Neighbor States for neighbor state descriptions.


Troubleshoot the OSPF Routing Table


Troubleshoot OSPF Init State

Refer to Why Does the show ip ospf neighbor Command Reveal Neighbors in the Init State? for an Init State problem description and troubleshooting steps.


Troubleshoot OSPF MTU


Note: If the problem is related to Layer 2, check if a proxy ARP is enabled. If it is enabled, disable it, and use the clear ip arp command in order to clear the ARP cache.

Troubleshoot OSPF Corrupt Packets


Troubleshoot OSPF Two-Way State

Refer to Why Does the show ip ospf neighbor Command Reveal Neighbors Stuck in 2-Way State? for an OSPF Two-way State problem description and troubleshooting steps.


Troubleshoot OSPF Links


You can use an Embedded Event Manager (EEM) script to troubleshoot the links flapping.

For more information, refer to this Cisco Support Community document that describes how to use an EEM script in order to collect information from a router when there is an OSPF flap: Troubleshooting OSPF Flaps with EEM Script

Troubleshoot Full Adjacency


Troubleshoot External Link-State Advertisements

Refer to Common Routing Problem with OSPF Forwarding Address for a description of forwarding addresses in external LSA, and for troubleshoot steps concerning the most common problems with LSAs having non-zero forwarding addresses.


Troubleshoot OSPF NBMA Networks

Refer to Problems with Running OSPF in NBMA Mode over Frame Relay for more information on common OSPF over NBMA network problems.


Troubleshoot Access Lists


Troubleshoot Neighbors over PRI


Troubleshoot Ping


Troubleshoot the OSPF Interface


Troubleshoot Frame Relay Environment


Troubleshoot External Route Problems


Troubleshoot Network Type


Troubleshoot OSPF Area Type


Troubleshoot the Hello/Dead Interval Mismatch


Note: Debug output from the debug ip ospf hello command shows the mismatch in hello parameters. Here is the sample debug output:

debug ip ospf hello
*Oct 12 14:03:32.595: OSPF: Send hello to area 0 on FastEthernet1/0 from
*Oct 12 14:03:33.227: OSPF: Rcv hello from area 0 from FastEthernet1/0
*Oct 12 14:03:33.227: OSPF: Mismatched hello parameters from

!--- Indicates that there is mismtached hello parameters from

*Oct 12 14:03:33.231: OSPF: Dead R 2 C 3, Hello R 1 C 1 Mask R C
*Oct 12 14:03:33.531: OSPF: Send hello to area 0 on FastEthernet1/0 from

Related Information

Open a TAC Case What Do %OSPF-4-ERRRCV Error Messages Mean? Open a TAC Case How Does OSPF Generate Default Routes? OSPF Tips for the Cisco 1600 and 800 Open a TAC Case OSPF Neighbor States OSPF Route Check Init State Check MTU Check Corrupted Packet Check Two-Way Check Link Check Full Adjacency Check External LSA Check Contact the TAC Contact the TAC NBMA Broadcast Check ACL Check Open a TAC Case Contact the TAC Neighbors over PRI Check Open a TAC Case Return to Main Flow Contact the TAC Why Does the show ip ospf neighbor Command Reveal Contact the TAC Ping Check OSPF Interface Check Check OSPF Neighbor States Frame Relay Environment Check Why Are Some OSPF Routes in the Database but Not the Routing Table? Open a TAC Case External Route Check Open a TAC Case Check Init State Init State Check Contact the TAC Configuring OSPF ACL Check Contact the TAC Link Check Link Check Contact the TAC Network Type Check Open a TAC Case Open a TAC Case Open a TAC Case Problems with Running OSPF in NBMA Mode over Frame Relay Open a TAC Case Contact the TAC Area Type Check NBMA Broadcast Check Hello/Dead Interval Check Area Type Check Open a TAC Case Neighbor over PRI Check Area Type Check

Updated: Sep 15, 2008
Document ID: 12151