Kemp Load Balancers

In a previous article, Configure Kemp Load Balancer for Exchange 2016, we explored how to make client access services highly available for Exchange 2016. In this article, we continue that trend by making the Simple Mail Transfer Protocol (otherwise known as SMTP) highly available.

If you don’t have a load balancer you can download one for free from Kemp. Kemp’s free appliance is what we will use in this guide.

Don’t worry. Despite the focus being on Kemp, you can translate these principles to any vendor.

Let’s get started!

Disclaimer: I need to point out that I am not sponsored by Kemp in any way. However, this document does contain some affiliate links.

The environment

In our example below we plan to have two Exchange 2016 servers behind a load balancer in a single site; EX16-01 and EX16-02.

With each release of Exchange, we have seen a substantial shift in the way it required load balancers to be configured. For example, between Exchange 2010 and 2013, the requirement for session affinity was dropped. This allowed multiple requests from a single client to take different paths to its mailbox. It no longer mattered which client access servers in a site were involved in the session. This was a contrast to 2010 where a client session had to maintain a single path at all times. Ross Smith covers this in greater detail here.

Exchange 2013 also dropped support for traditional RPC connections. All client connections to Exchange 2013 were flipped to RPC over HTTP. Service Pack 1 saw another shift in client connectivity as it introduced the option of MAPI over HTTP (although disabled by default). This faster, leaner protocol allowed the Exchange Team to develop shorter failover times between servers. It introduced another virtual directory into the mix–the MAPI virtual directory–which would need to be load balanced as well.

Unlike its predecessor, Exchange 2016 did not see a shift in client connectivity. With Exchange 2016 an organization can choose between MAPI over HTTP, or, RPC over HTTP (although the former is now preferred).

Knowing the nuances between each version of Exchange can be daunting. Equally daunting is the configuration of the load balancer itself. But it doesn’t have to be.

A good vendor will give you instructions on load balancing Exchange.
A great vendor will give you a template to automate setup.

Which is lucky because this article is about a great vendor.

In this article, we configure the Kemp load balancer to provide high availability for Exchange 2016. If you don’t have a load balancer you can download one for free from Kemp. Kemp’s free appliance is what we will use in this guide.

Don’t worry. Despite the focus being on Kemp, you can translate these principles to any vendor.

Let’s get started!

Disclaimer: I need to point out that I am not sponsored by Kemp in any way. However, this document does contain some affiliate links.

The environment

In our example below we plan to have two Exchange 2016 servers behind a load balancer in a single site; EX16-01 and EX16-02.