When establishing your cluster network infrastructure, you can establish a demilitarized zone (DMZ) separated by using firewalls to control access to your more critical systems in the backend. Use an intermediary server in the DMZ to perform the necessary routing and load balancing tasks. See the figure below:
Using an Intermediary Server
SAP provides the SAP Web dispatcher that you can use as the intermediary server. The SAP Web dispatcher is a load-balancing device provided free-of-charge to SAP customers that operates using the SAP application server load-balancing mechanisms. It supports the use of SSL for securing connections and does have URL filtering capabilities. It can be used with both ABAP and J2EE installations.
You can also use different devices as the intermediary server, for example, an Apache Web server as a reverse proxy. Such devices often provide additional features such as more refined load-balancing, or request and content filtering. The features provided depend on the product you are using.