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Cisco Bug: CSCtc73440 - Changing interface ip address/mask triggers a bad OSPF route

Last Modified

Jan 28, 2017

Products (1)

  • Cisco IOS

Known Affected Releases


Description (partial)



When the IP address/mask of an interface that OSPFv2 is using as the next hop
for a route is changed such that the nexthop IP address no longer falls
within the interface subnet, OSPF may install a recursive path (i.e. one
with no interface) in the RIB. These recursive routes can persist even after
OSPF runs subsequent SPF calculations.


In order for this problem to be seen the ip address/mask configuration change
must occur within a specific time window during an SPF calculation. Small or
moderate sized networks (<10,000 OSPF routes) are unlikely to see this. Also,
IOS releases that have the OSPF local RIB feature are not vulnerable..
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Bug Details Include

  • Full Description (including symptoms, conditions and workarounds)
  • Status
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