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Cisco Bug: CSCta24035 - Increase VLAN Detect Interval to 15 minutes

Last Modified

Nov 13, 2016

Products (1)

  • Cisco NAC Appliance (Clean Access)

Known Affected Releases


Description (partial)


This happens in a NAC setup L2VGWOOB using the core switch in redundancy mode and access switch for clients.  client VLANs are trunked from access switch to core.
Before authentication due to vlan mapping traffic is sent through the untrusted to trusted port of CAS as a result core switch has the MAC entry of trusted VLAN and CAS trusted port. 
After authentication this switch entry is not updated, as a result traffic from other subnets are sent to CAS trusted port instead of sending it directly to the PC. CAS backholes this traffic as a result.


This happens in a unique setup with core switch redundancy, where it takes time for CAM table on two core switches to merge. Half of the VLAN's are forwarded to one switch and half of the other VLANs sent through other switch. Hence CAM table needs to be refreshed on both switches.
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