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Cisco Bug: CSCsz29991 - CPU at 100% with clear ip ospf process and %OSPF-4-NULL_PREV_LINKAGE wit

Last Modified

Feb 15, 2018

Products (1)

  • Cisco IOS

Known Affected Releases


Description (partial)


Error message: %OSPF-4-NULL_PREV_LINKAGE with a traceback upon executing "clear ip ospf process"

Which will spike the CPU to 100% forever ultimately leading to a Sup/RSP crash. The crash could happen immediately or even after several hours.


A "clear ip ospf process" especially in an environment having multiple OSPF process and learning the same prefix via different processes could end up with the above issue due to a race/timing condition.
In this case it was due to the fact that one process was having a "default-information originate always" CLI causing an implicit redistribution and the other process also learning a default route as E2. Clearing the IP OSPF process i.e. both the process the hard way could lead to the above issue.
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