If you can set the Real Server to route return traffic to the LoadMaster interface, transparency can be set for the Virtual Service. Using routing tables may be required to prevent asymmetric routing.

Note: Transparency currently cannot be used in conjunction with cloud High Availability (HA) because there is no shared IP address.

If you are seeing the following scenario:

  • With transparency disabled, the LoadMaster sends traffic to a healthy Real Server as normal and the Real Server responds.
  • With transparency enabled, the LoadMaster sends traffic to a healthy Real Server as normal. However, no traffic is seen on the Real Server.

This is due to the IP forwarding setting in Azure or the source/destination checks setting in Amazon Web Services (AWS).

For further information on IP forwarding in Azure, refer to the following Microsoft content: Enable or disable IP forwarding.

You can find this in the Azure portal by going to: Home > <Virtual LoadMaster (VLM)> > Networking > <VLM NIC/Interface> > IP configurations.

Set IP forwarding to Enabled.

This change must be made on the interface that is on the same subnet as the Real Server.

For further information on Source/Destination Checks in AWS, refer to the following AWS content: Disabling Source/Destination Checks.

You can find this in the AWS portal by selecting the EC2 instance (the LoadMaster) and going to: Actions > Networking > Change Source/Dest. Check. This must be disabled.