Firewall load balancing balances traffic flows to one or more firewall farms.
A firewall farm is a group of firewalls that are connected in parallel or that have their “inside” (protected) and “outside” (unprotected) interfaces connected to common network segments.
Firewall load balancing requires a load-balancing device (IOS SLB) to be connected to each side of the firewall farm. A firewall farm with “inside” and “outside” interfaces would then require two load-balancing devices—each making sure that traffic flows are directed toward the same firewall for the duration of the connection. Figure 10-3 illustrates the basic firewall load-balancing concept.