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Cisco Bug: CSCvt57119 - Traffic sent untagged after toggling untagged to trunk while link down

Last Modified

Oct 03, 2020

Products (24)

  • Cisco Nexus 9000 Series Switches
  • Cisco Nexus 9516 Switch
  • Cisco Nexus 9396TX Switch
  • Cisco Nexus 9396PX Switch
  • Cisco Nexus 93108TC-FX Switch
  • Cisco Nexus 93120TX Switch
  • Cisco Nexus 93240YC-FX2 Switch
  • Cisco Nexus 9332C Switch
  • Cisco Nexus 9504 Switch
  • Cisco Nexus 9372TX-E Switch
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Known Affected Releases

13.2(7k) 14.2(3n)

Description (partial)

A Cisco ACI leaf switch sends traffic that is untagged for a particular VLAN even though it is configured as trunk (tagged).

The issue has been recreated in the following scenario:
1. Configure a vPC in Cisco ACI.
2. Deploy the vPC within an EPG and set the VLAN to "untagged" or "802.1p".
3. Bring down one side of the vPC (for testing you can shut the remote end of the link).
4. While the above link is down, change the EPG deployment of the VLAN to "trunk" so that the VLAN should be trunked.
5. Bring up the down side of the vPC.

The side of the vPC where the link was down while the change was made will continue to send the configured VLAN as untagged, whereas the side of the vPC that was up will send the traffic as tagged.
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