Failover
Understanding Failover
Failover, also known as "High Availability", allows a second ADC to take over quickly if the
primary unit fails allowing data and applications to be continuously delivered without interruption.
The load balancing pair can be configured into an active/standby (also known as Active/Passive)
mode or in Active/Active mode.
In an Active/Passive failover configuration, two Equalizers are configured into active and passive
roles, with the active unit serving cluster traffic. A "failover" is said to occur when the active
Equalizer stops processing client requests and the passive Equalizer starts processing cluster
traffic.
When two Equalizers are configured into this type failover configuration, they form what is called
a "failover pair". An Equalizer in a failover pair is called a "peer". At any given time, only one of
the Equalizer s in a failover pair actually services requests sent to the cluster IP addresses
defined in the configuration -- this unit is called the "active peer" or the "current primary"
Equalizer in the pairing. The other Equalizer, called the “passive peer” or "current backup", does
not process any client requests.
Both units continually send "heartbeat probes" or "failover probes" to one another. If the current
primary does not respond to heartbeat probes, a failover occurs. In this scenario the current
backup Equalizer assumes the primary role by assigning the cluster IP addresses to its network
interfaces and begins processing cluster traffic.
In an Active/Active failover configuration, clusters are active on both peers in the configuration.
Active/Active failover situations are the same failure situations that cause a peer to take over all
the cluster and floating IP addresses in an Active/Passive failover configuration. A healthy peer
will take over all of the cluster and failover IPs. This type of failover configuration is only
available when using two Equalizers using EQ/OS 10.
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Copyright © 2014 Coyote Point Systems, A Subsidiary of Fortinet, Inc.
Summary of Contents for Equalizer GX Series
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