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Cisco Bug: CSCvu51926 - Implicit arp rule reshuffled to tile from tcam resulting in contract deny

Last Modified

Oct 03, 2020

Products (24)

  • Cisco Nexus 9000 Series Switches
  • Cisco Nexus 9516 Switch
  • Cisco Nexus 9396PX Switch
  • Cisco Nexus 9396TX Switch
  • Cisco Nexus 93108TC-FX Switch
  • Cisco Nexus 93120TX Switch
  • Cisco Nexus 93240YC-FX2 Switch
  • Cisco Nexus 9372TX-E Switch
  • Cisco Nexus 9332C Switch
  • Cisco Nexus 93108TC-EX Switch
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Known Affected Releases


Description (partial)

ARP packets are dropped in the fabric that should be implicitly permitted using zoning-rule programming. The packet drop reason is SECURITY_GROUP_DENY and the specific rule is implicit deny for the VRF table.

This issue can occur if there are approximately 5000 or more vzAny contract TCAM rules (i.e sclass=any, dclass=any) with valid protocol and l4 filters. 

This unusally high number of vzany rules results in the rules getting moved from one memory in hardware to another memory, which exposes a software bug. Even an implicit ARP entry, which internally is a vzAny filter rule, is also impacted by this move.
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