Exchange 2013 DAG - Load Balancing for ActiveSync, OWA, and Outlook Anywhere

I am looking for an inexpensive solution for OWA, ActiveSync, and Outlook Anywhere to work publicly if an Exchange Server goes down. We have two Exchange 2013 servers with all roles installed setup in DAG and using DNS RR internally. For public, goes to the firewall and is NAT'd to one Exchange server. Obviously if that Exchange server goes down, so does everything publicly pointing to There are two separate public IPs for each Exchange server, so we can update the public DNS IP if there is a server issue. Not the most ideal solution. I am not thrilled with WNLB and this is a VMware environment and I have seen issues with WNLB in the past when running on VMware. Haven't tried recently, but I still would rather not use it. Cost is the biggest concern, and whatever load balancer that is used, I would prefer to run on ESXi.

I've used Riverbed Stingray before for websites. Not overly thrilled with it as I have seen issues with HTTPS when running two Stingrays in HA and a OS issue caused HTTPS to stop working and didn't fail over properly to the secondary load balancer. I always hear F5 is supposed to be one of the bests and see many people talk about KEMP with Exchange. At this point, I don't have pricing on any of them.

Right now Outlook Anywhere isn't even setup with the address, but that needs to be changed. Outlook is only used internally or over VPN, but there are still plenty of users connecting via OWA and ActiveSync.
Keith PratolaSenior Systems ArchitectAsked:
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Simon Butler (Sembee)ConsultantCommented:
Kemp or Jetnexus are the two load balancers that I deploy most widely.
You can run both in VMs, which will bring the cost down considerably.

Another option for external traffic would be a cloud based load balancer. There are a couple of those around which would possibly work for your external traffic.

WNLB wouldn't work for you as you cannot use it on a server with the DAG role. It is also not recommended by the Exchange product team.

Depending on the number of users involved, the free version of Kemp's load balancer might work for you, but it is limited on throughput.


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Keith PratolaSenior Systems ArchitectAuthor Commented:
Great, thanks! It is about 1,800 users. Is the free trial of Kemp also the free version? Sounds like that would be worth while to keep in my lab. I didn't see anything on Kemp's website that specifically said a free version.
Simon Butler (Sembee)ConsultantCommented:
The free load balancer is on its own web site.

The trial isn't the same thing.

Lab use is what they are suggesting it for.
I don't think the free version will work for 1800 users though.

Keith PratolaSenior Systems ArchitectAuthor Commented:
Thank you again! No, I wouldn't use the free version in production.
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