Definition of terms

Frontend

When visiting the virtual server service, the client will create a connection with FortiADC — this connection between the client and the virtual server is referred to as the "frontend".

Backend

After FortiADC receives the request from the client, FortiADC will load-balance the request back to the real servers — this connection between FortiADC and the real server is referred to as the "backend".

Source IP address (frontend)

From the frontend connection, the source IP address refers to the client address.

Destination address (frontend)

From the frontend connection, the destination address refers to the virtual server address.

Source IP address (backend)

From the backend connection, the source IP address refers to FortiADC's outgoing interface IP address.

Destination address (backend)

From the backend connection, the destination IP address refers to the real server address.