Exchange 2010 ARR

Morikk
Morikk used Ask the Experts™
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Setting up a new Exchange 2010 environment with Server 2008R2 ARR IIS server for my front end OWA access.  Question is should I setup load balancing on my ARR server, or Windows NLB my Client Access Array and point my ARR server to the cluster?

I have tested both solutions and both seem to work, though I am not testing under a heavy load.

Setting up the load balance on ARR requires client affinity, while using NLB on the CA cluster automatically by design will connect the client with only one node.  (I believe)
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Gareth GudgerSolution Architect
Most Valuable Expert 2014
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Commented:
Have you seen this article?
http://technet.microsoft.com/en-us/library/ff625247(v=exchg.141).aspx#affinity

I believe you are correct. You may have to go to a layer 7 hardware load balancer to accomplish this.

Author

Commented:
Well using IIS ARR Client affinity cookie seems to work, and also using WNLB IP affinity is keeping the client on one node as well, so my question is which would be the preferred method.
Most Valuable Expert 2014

Commented:
The RPC CAS array address should NOT be used for anything other than MAPI TCP traffic. The address should be used internally only, for that service only and should not resolve externally.

The Exchange product team don't recommend the use of Windows NLB, which is a good thing because it sucks. I also cannot find anything that indicates that ARR on Windows 2008 R2 is supported. Therefore it doesn't really matter which solution you use, you are likely to be unsupported or have problems with either.
I can find Windows 2012 ARR guidelines with Exchange 2013 though.

I wouldn't have bothered with the separate CAS role servers myself, spent the money on a real load balancer instead.

Simon.
Commented:
Well as I have tested for a bit this week it appears using ARR affinity rules is the better choice out of the two.  I appreciate the info, but a hardware load balance solution is not possible at the moment

Using ARR affinity over WNLB has shown to be more reliable and even more responsive in my small amount of testing.

Author

Commented:
My choices for solution were WNLB or or MS ARR server using Client Affinity.

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