Load balancing : Load balancing among local servers : Distributing new sessions among your servers : Applying full NAT to forwarded packets
 
Applying full NAT to forwarded packets
When the virtual server type is L4 Load Balance, you can configure the virtual server to rewrite the source and destination IP addresses for packets before FortiADC routes them.
FortiADC provides the following packet-forwarding options for layer 4 load-balancing virtual servers:
Direct routing
Forwards the source and destination IP addresses with no changes.
When Direct routing is selected, the IP address of the virtual server is the same as the back-end server’s address. The back-end server replies directly to the client, either through FortiADC or directly, depending on the configuration.
NAT
Replaces the destination IP address with an IP address from a pool of IP addresses that you define.
The destination IP address of the initial request is the IP address of the virtual server. Configure FortiADC as the default gateway on the back-end server to ensure the reply goes through FortiADC.
FullNAT
Rewrites both the destination and source IP addresses.
The source IP address is replaced by an IP address from the pool you define using Server Load Balance > Resources > IP Pool. The destination IP address is replaced with an IP address from a pool of IP addresses that you define.
To configure full-NAT mode for a virtual server
1. To specify the IP addresses to use, go to Server Load Balance > Resources > IP Pool.
2. In the configuration, for the layer 4 load balancing virtual server, for Packet-Forwarding Method, select FullNAT.
3. In the Resources section, for Source Pool, select the IP address pool you created.