This document describes how to troubleshoot common problems with Open Shortest Path First (OSPF).
There are no specific requirements for this document.
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, ensure that you understand the potential impact of any command.
Refer to Cisco Technical Tips Conventions for more information on document conventions.
Note: Only registered Cisco users have access to internal Cisco tools and information.
Troubleshoot OSPF Neighbor States
Refer to OSPF Neighbor States for neighbor state descriptions.
Troubleshoot the OSPF Routing Table
Troubleshoot OSPF Init State
Refer to Troubleshoot OSPF Neighbor Problems for more information on the OSPF Init State.
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
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: Troubleshoot OSPF Flaps with EEM Script.
Troubleshoot Full Adjacency
Troubleshoot External Link-State Advertisements
Troubleshoot OSPF NBMA Networks
Refer to Troubleshoot Open Shortest Path First Route Database Issues for more information on this topic.
Troubleshoot Access Lists
Troubleshoot Neighbors over PRI
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
The debug output from the debug ip ospf hello command shows the mismatch in hello parameters. Here is an example of the debug output:
*Oct 12 14:03:32.595: OSPF: Send hello to 10.224.0.5 area 0 on FastEthernet1/0
*Oct 12 14:03:33.227: OSPF: Rcv hello from 10.1.1.1 area 0 from FastEthernet1/0
*Oct 12 14:03:33.227: OSPF: Mismatched hello parameters from 192.168.12.1
!--- Indicates that there is mismtached hello parameters from 192.168.12.1
*Oct 12 14:03:33.231: OSPF: Dead R 2 C 3, Hello R 1 C 1 Mask R
255.255.255.0 C 255.255.255.0
*Oct 12 14:03:33.531: OSPF: Send hello to 10.224.0.5 area 0 on
FastEthernet1/0 from 192.168.12.2