About Failover and Load Balancing

Failover and Load Balancing (LB) (together, FLB) is a mechanism that actively monitors WAN connections and acts accordingly on failure/recovery of the WAN interface(s). The overall effect is a system-wide response to failure/recovery of WAN connections. Even if you only have one WAN, you still benefit because of faster recovery procedures performed on that one WAN as normal part of FLB (for more information about FLB with one WAN, see Knowledge Base article, SW13851, Can I disable global Load Balancing if only one WAN is used on the firewall?). In essence, FLB provides a highly-available system.

IMPORTANT: It is recommended that Load Balancing be enabled at all times, even if there is only one WAN. For more information, see Can I disable global Load Balancing if only one WAN is used on the firewall? (SW13851).

For FLB, multiple WAN members are supported (N–1), where N is the total number of interfaces on a hardware platform). For example:

The Primary WAN Ethernet Interface has the same meaning as the previous concept of “Primary WAN.” It is the highest ranked WAN interface in the LB group. The Alternate WAN #1 corresponds to “Secondary WAN,” it has a lower rank than the Primary WAN, but a higher rank than the next two alternates. The others, Alternate WAN #2 and Alternate WAN #<n–1>, are new, with Alternate WAN #<n–1> being the lowest ranked among the four WAN members of the LB group.