ePrism User Guide - EdgeWave

HALO Overview
Load Balancing
Although the ePrism cluster will be treated as one system, email is processed independently by
each cluster member, and requires the use of a load balancing system to distribute mail flow
between the systems in the cluster.
Load Balancing via DNS
A DNS round-robin technique can be used to distribute incoming SMTP connections via DNS to
the systems in the cluster, as shown in the following example MX records:
example.com IN MX 10 mail1.example.com
example.com IN MX 10 mail2.example.com
Priority can be given to specific servers by configuring different priority values, as follows:
example.com IN MX 5 mail1.example.com
example.com IN MX 10 mail2.example.com
Using a Load Balancer
You can also use a hardware load balancing device, such as the F5 BIG-IP, Cisco, or other similar
load balancer. The load balancer is configured to send the mail stream to systems in a cluster. If
one of the systems fails, the load balancer will automatically detect this event and distribute the
load between the remaining systems.
The load balancer can be configured to distribute the mail stream connections intelligently across
all systems in the cluster, using techniques such as round-robin, and distribution by system load
and availability.
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