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After migrating Kemp HA to new hypervisor environment, master/master scenario





Migrated LoadMasters to a new VMWare environment and each node in the pair sees itself as the active node and the other as unreachable (although both are accessible).


Product: Loadmaster

Version: Any

Platform: Virtual

Application: N/A

Question/Problem Description:
  • Two LoadMasters were migrated to different vCenter environment.
  • Live vMotion migration was done across it.
  • Once migrated, each node displayed itself as being the active in the pair and the other as being unreachable.
  • Rebooted both VLMs but were still facing issues.
  • One node was shutdown to stabilize situation.
Steps to Reproduce:  
Error Message:  
Defect Number:  
Enhancement Number:  

Environment did not have the VMware requirements in place with regards to virtual switch settings to allow proper HA operation.


Configure the VMware distributed switch settings to allow forged transmits and mac address changes under security settings are properly configured on new environment.

Both Units Think That They_2.png

Ensure that MAC Address Changes and Forged Transmits are both selected. When they have been selected, reboot one of the LoadMasters.

Both Units Think That They_3.png

The units should now be able to communicate properly. The correct state should now appear in the HA status icons.


  • Mac Address Changesallows virtual machines to receive frames with a MAC address that is different from the one configured in the VMX.

    Forged Transmitsallows the LoadMaster to accept packets where the source MAC address does not match the effective MAC address. The effective MAC address is set by the OS (the LoadMaster) and in the case of an HA failover, the source and effective MAC addresses will not match.

    Having MAC address changes and forged transmits set to reject can cause both units to believe they are the master unit.

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