F5 LTM Load Balancing from web to App servers
I have F5 BIG-IP which load balances the trafic that destined to my web servers from external and my webservers internally communicate with the Application server and what i want is to load balance this traffic initiated from web servers to application servers. Based on the connectivity I have there is no direct physical connectivity from F5 to the App servers so what is the best practice to achieve the load balancing from the web server to app servers?
Basically, you need to think of this traffic as a completely new traffic stream, separate to the traffic from external to the webservers. In this new stream, the webservers will be the client, and the appservers will be the server/destination.
So, set up a new virtual server (ensure that only the web servers are allowed to connect to it, for security reasons. You can do this by locking it down to vlans/tunnels or by putting in the source addresses), then create a new pool for the appservers and connect the pool to the newly created virtual server.
As you mentioned that you don't have a physical connection with these app servers, you may need to enable SNAT (Automap probably easiest in your scenario) and ensure that the F5 can route to the appservers.
Hope this helps.