Mitigate networking issues after a MAC address change of a VNIC in a Virtual Machine Guest Operating System

Products

• VMware vSphere ESXi

Issue/Introduction

• MAC address of the VNIC in the Virtual Machine Guest Operating System is changed.
  
  
  
  
  
• MAC address changes is enabled on the Distributed Port Group to which the guest Virtual Machine connects.
  
  
• Distributed Port Group Ports  Port is blocked.
  
  

Environment

VMware vSphere 9.x
VMware vSphere 8.x
VMware vSphere 7.x
VMware vSphere 6.7.x

Cause

The distributed port group may be blocked if a duplicate MAC or Distributed Port Group Security MAC address changes policy is not updated.

Resolution

• Ensure that the MAC address is not a duplicate.
• Confirm the Security Policy for the Distributed Port Group MAC address changes is set to Accept.
  
  
  
  
• Re-enable the interface on the Virtual Machine, Edit Settings -> Network adapter (Deselect/Re-Select) Connected.
  
  
  
  
• Confirm that the Distributed Port Group port is not blocked.
  
  

 

Additional Information

MAC Address Changes

The security policy of a virtual switch includes a MAC address changes option. This option allows virtual machines to receive frames with a Mac Address that is different from the one configured in the VMX.