Chapter 5 High Availability (HA)

5.1 Overview

As the network applications develop, customers have higher and higher requirements for the reliability of the network and network appliances. During network planning and design, to improve the reliability of the network, some critical network appliances must have redundancy protection mechanisms. The Clustering function mentioned in the “Clustering” chapter uses the VRRP technology to solve the single-point failure. This chapter will introduce the High Availability (HA) function that newly provided by FortiBalancer appliances. The HA function not only solves the single-point failure, but also provides more policies to ensure the network reliability.

The HA function allows two or more FortiBalancer appliances to continuously exchange the running status with each other, and keep their configurations synchronized. When an appliance becomes down, other available appliances will take over the application services on the faulty appliance, which ensures the high availability of application services.

Besides, the HA function provides the Stateful Session Failover (SSF) function. With the SSF function, when a service failover occurs, connections on the service will be switched to the new appliance. This avoids the interruption of connections and therefore improves user experience. The HA function can be deployed flexibly. Besides the Active/Active and Active/Standby deployment scenarios, the HA function can be deployed among multiple appliances to achieve mutual-backup.