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

Last Modified

Feb 28, 2018

Products (1)

  • Cisco IOS

Known Affected Releases

12.0S()

Description (partial)

None

Symptom:

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.

Conditions:

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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  • Known Fixed Releases
  • Related Community Discussions
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