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Cisco Bug: CSCtd45731 - Few VRF routes are programed incorrectly in FIB

Last Modified

Feb 08, 2017

Products (12)

  • Cisco Nexus 7000 Series Switches
  • Cisco Nexus 7000 10-Slot Switch
  • Cisco MDS 9124 Multilayer Fabric Switch
  • Cisco MDS 9222i Multiservice Modular Switch
  • Cisco MDS 9216i Multilayer Fabric Switch
  • Cisco MDS 9509 Multilayer Director
  • Cisco MDS 9134 Multilayer Fabric Switch
  • Cisco Nexus 7000 18-Slot Switch
  • Cisco MDS 9506 Multilayer Director
  • Cisco MDS 9124e 4G FC HP Blade Switch
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Known Affected Releases

4.2(2a) 4.2(3)

Description (partial)

 A Cisco Nexus 7000 switch may have an inconsistency between it's IPv4
 unicast RIB and FIB, such that VRF routes are incorrectly programmed
 into the FIB.
 This is a timing issue that can occur when a large number of routes
 are changing in different routes at the same time.
 ISSU and module reload are good examples of this condition, as well as
 severe network changes.
 The incorrect routes can be detected by running the RIB to FIB
 consistency checker:
 test forwarding inconsistency
###One should not use this command to do health check. So if we see the
inconsistent route then you may want to use it.######
 And fixed using some variant of the the clear forwarding or clear
routing commands.
 Further Problem Description:
 This problem occurs only with a large number of routes when they are
 changing in different VRFs at the same time as the RIB tries to round
 robin the time it spends distributing routes to the FIB, i.e. to avoid
 starvation of any one VRF.

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Bug Details Include

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  • Status
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