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Load Balancing for Web Farms: ARR vs NLB

Question

Tuesday, October 9, 2012 1:25 PM

Hi there,

I'm wondering what's better for load balancing for my WFF environment, Network Load Balancing or  Application Request Routing.

I have set-up a Web Farm Framework (3 servers - one controller, one primary, one secondary). IIS settings, site, application data and file synchronization is working great. Now I want to be able to load balance it - access by one IP address or domain name, control affinity, drain for maintenance, choose multicast/unicast, etc.

So here are my questions:

1. I know NLB can do all of that based on IP address. So I can probably use NLB to share IP addresses between my primary and secondary nodes and bind those IP addresses on the sites I set-up in IIS on my WFF (I am planning to have more than 100 sites, using their own IP addresses and SSL certificates). Would NLB work fine in that environment?

  1. Can ARR do all that and work on its own, or does it work ONLY in conjunction with NLB?

  2. What is the difference between NLB and ARR?

Thanks!
-znerses

All replies (5)

Tuesday, October 9, 2012 3:12 PM âś…Answered

  1. NLB can do what you are asking.
  2. ARR can also, and no you do not have to use NLB with ARR.
  3. NLB is a simpler implementation of Load Balancing than ARR.  ARR has several more configureation options than NLB.

If you are uncertain which load balancing option will work best for you please spend some time reviewing these articles and the related articles linked with-in each of these.

 Application Request Routing
http://www.iis.net/downloads/microsoft/application-request-routing

Network Load Balancing Technical Reference
http://technet.microsoft.com/en-us/library/cc739506(v=ws.10).aspx

Tuesday, October 9, 2012 3:28 PM

Hi Lou,
Thank you for your quick answer and links you provided.

I had already read some of that and I am reading some more, but please let me know if this impression I have is correct:

Seems like ARR is better than NLB from the high-availability standpoint, because if one of the nodes is throwing .net framework or other errors, NLB won't know about it to stop sending requests to failed server, unless it's not responding at all. Meanwhile ARR has more options to see if the responds have errors in them.

Is that a correct assessment?
Please clarify.

  • znerses

Tuesday, October 9, 2012 3:32 PM

 And one addition question, I hope you can tackle this one too.

With NLB I can use my Web Farm Framework's primary and secondary nodes to also be my NLB nodes. With ARR - do I have to have a separate server running ARR and directing traffic to my web farm's nodes?

Thank you so much in advance!

Thursday, November 1, 2012 7:12 PM

On NLB configuration all servers should be in load balancing (both primary and secondary). You can change the primary server at any time (for example when it fails).
With ARR you need to have dedicated server (or two) for Controller needs. Do not install ARR on yours Secondary/Primary servers! I've got a lot of issues when I deployed ARR in the whole farm (mostly with machine.config corruption).

Tuesday, January 22, 2013 11:54 AM

Hi LukaszH,
Thanks again for the input.

In theory if I go with 'WFF + NLB between nodes' option and if I have only one ARR controller and it goes down - will customers still be able to access the website on the webfarm? The IP address clients request is in NLB between primary or one of the secondary nodes, so will it still work, or we need ARR to control that traffic?

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