Preview Tool

Cisco Bug: CSCun86405 - Orphan Ports on FEX have the MAC learnt on ES ID instead of local SWID

Last Modified

Aug 07, 2019

Products (7)

  • Cisco Nexus 7000 Series Switches
  • Cisco Nexus 7000 10-Slot Switch
  • Cisco Nexus 7000 4-Slot Switch
  • Cisco Nexus 7700 18-Slot Switch
  • Cisco Nexus 7000 18-Slot Switch
  • Cisco Nexus 7700 10-Slot Switch
  • Cisco Nexus 7000 9-Slot Switch

Known Affected Releases


Description (partial)

Orphan ports connected over FEX HIF may observe traffic getting black holed due to incorrect learning of MAC address in a VPC+ domain.
The MAC is learned from Emulated SWID (ESID) instead of Local SWID as observed on other switches in FabricPath Domain.

On the problem switch:
Software MAC learning would pick on the right physical port, though hardware MAC tables would shows MAC learned from ESID instead of Local SWID.

Problem may trigger if ports which were part of VPC+ complex (VPC port-channel) and were then moved to FEX-Fabric mode using channel-group force option. 
This does not clear the register setting properly and MAC learning still picks on ESID as is treated to be coming across a VPC+ Port-channel.

This is the only known and analyzed trigger though may not be the only one.
Bug details contain sensitive information and therefore require a account to be viewed.

Bug Details Include

  • Full Description (including symptoms, conditions and workarounds)
  • Status
  • Severity
  • Known Fixed Releases
  • Related Community Discussions
  • Number of Related Support Cases
Bug information is viewable for customers and partners who have a service contract. Registered users can view up to 200 bugs per month without a service contract.