One configuration option you can use with the BIG-IP® system is a one-IP network topology. This differs from the typical two-network configuration in two ways:
Part of this configuration requires you to configure the BIG-IP system to handle connections originating from the client. You must define a SNAT in order to change the source address on the packet to the SNAT external address, which is located on the BIG-IP system. Otherwise, if the source address of the returning packet is the IP address of the content server, the client does not recognize the packet because the client sent its packets to the IP address of the virtual server, not the content server.
If you do not define a SNAT, the server returns the packets directly to the client without giving the BIG-IP system the opportunity to translate the source address from the server address back to the virtual server. If this happens, the client might reject the packet as unrecognizable.
The single interface configuration is shown in the following illustration.
You can perform these tasks to configure a one-IP network topology.