This chapter covers the following OSPF troubleshooting topics:
• Troubleshooting OSPF neighbor relationships
• Troubleshooting OSPF route advertisement
• Troubleshooting OSPF route installation
• Troubleshooting redistribution problems in OSPF
• Troubleshooting route summarization in OSPF
• Troubleshooting CPUHOG problems
• Troubleshooting dial-on-demand routing (DDR) issues in OSPF
• Troubleshooting SPF calculation and route flapping
• Common OSPF error messages
This chapter discusses common problems of OSPF and tells how to troubleshoot those prob-lems. OSPF is a complex protocol when compared to RIP or IGRP. Sometimes, the problems can be relatively easy to troubleshoot and require few configuration changes. Other times, the problems can be very complex and require more assistance.
This chapter discusses several types of problems. These examples have been collected over several years from real customer network environments.
Some problems require turning on debugs. Debugs in OSPF normally are not very CPU-intensive unless the problem is impacting the entire OSPF network. For example, if OSPF neighbors are not coming up, turning on debug ip ospf adj is not CPU-intensive unless 300 neighbors are having problems at the same time.
The flowcharts that follow document how to address common problems with OSPF with the methodology used in this chapter.
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