Deciding if the benefits of deploying a firewall load balancing solution out weigh the security risks depends on the company’s security policy and requirements. If deployed properly there are many benefits to load balancing firewalls. Researching this topic was difficult. There are many different views within blogs on this topic as well a few general sources covering firewall load balancing (FWLB). The majority of the general sources are either outdated or very vague.
The benefits of firewall load balancing as stated by McKeag, are redundancy through a failover configuration, increased through output, scalability, and they ability to build server banks. Server banks allow only the traffic that is required for the network appliance and blocks other traffic, therefore hardening the servers.
The network requirements, resources, and enterprise configuration will dictate if the servers will communicate with each other using specialized protocols developed by the vendor or a separate network appliance for load balancing.
Some of the security risks of firewall load balancing are the software vender’s use for the communication of the firewalls. The software must be updated and secured. Firewalls that are not load balanced do not communicate with other firewalls and therefore are easier to secure than firewalls using vender provided software to communicate with other firewalls. By using an appliance to balance the firewall load and creating server farms you reduce this risk by only allowing the required network traffic through the firewall.
Using network appliances to load balance firewall traffic requires two appliances on both sides of the firewall, much like a sandwich. The network appliances are the bread and the firewall is the filling. The benefits of using a separate network appliance for firewall load balancing are though output and scalability. The appliances need to support stateful connections by routing traffic back through the original firewall to ensure the valid