Earlier versions of IIS (6.0 and earlier) worked with Windows Load Balancer (WLB).  For later versions, Microsoft offers an IIS extension called ARR (Application Request Router). With Azure hosted sites, one can use the Azure Load Balancer.

Microsoft’s Application Request Router (ARR) IIS Extension is a complex piece of software which integrates with several other components to do its job. These components are URL Rewrite, Web Farm Framework and ARR’s External Cache module. For things to work correctly, not only do you need all components, but they must also be installed in a specific order, which can be confusing. Several years ago, Microsoft introduced the Web Platform Installer (WebPI) mechanism, which makes it easy to manage installed components.

Download all components

  1. Download and install the Web Farm Framework module. It is currently available in version 1.1
  2. Download and install the External cache module. It is currently available in version 1.0
  3. Download and install the URL Rewrite module. It is currently available in version 2.0
  4. Download and install ARR itself. It is currently available in version 3.0
  5. Start the IIS services back (or, simply reboot your server) and you should be good to go!

Create a Server Farm with ARR

  1. Open IIS Manager.

  2. In the Connections pane, expand the server node, and select Server Farms.

  3. In the Actions pane, click Create Server Farm.

    The Create Server Farm wizard opens to the Specify Server Farm Name page.

  4. In the Server farm name box, type a name for your server farm, and click Next.

    The Add Server page is displayed.

  5. In the Server address box, type the IP address of the first server, and click Add.

  6. Continue typing IP addresses and clicking Add until all web servers are entered.

  7. Click Finish.

What about Application Tier Load Balancing?

The web-tier is typically load balanced in a way that round-robins the requests to the app server farm. In other words, the Application Server Tier does not need a separate stand-alone load-balancer. The Web Load Balancer is all that is needed.

Summary

Load Balancing has changed significantly – from IIS 6.0 (and earlier) to recent IIS versions. For recent IIS versions, Microsoft’s Application Request Router is the standard solution. Application Server Farms typically do not need to be load-balanced, as that is handled by the Web Tier Load Balancer .

Anuj holds professional certifications in Google Cloud, AWS as well as certifications in Docker and App Performance Tools such as New Relic. He specializes in Cloud Security, Data Encryption and Container Technologies.

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Anuj Varma – who has written posts on Anuj Varma, Hands-On Technology Architect, Clean Air Activist.

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