IIS 7.0 - Application Request Routing (ARR)

Re: About ARR load balancing

wonyoo — Thu, 18 Jun 2009 14:46:53 GMT

Hi Joshua

ARR and NLB can be complementary, but they are not the same technology. Not sure if you had a chance to walk through some of the documents, but for your use case, it seems like the following may be most useful: http://learn.iis.net/page.aspx/486/http-load-balancing-using-application-request-routing/.

Unlike NLB, ARR is proxy based. So in your environment, you will want to have a 3rd machine as an ARR server which in turn load balances to the two servers that you already have in your environment. Another key difference is that NLB does its routing at layer 3 and 4 while ARR does its routing at layer 7 - so all of the headers and server variables are available to you to write more application specific rules to enable additional scenarios (as shown in http://learn.iis.net/page.aspx/487/pilot-program-management-using-application-request-routing/)

To answer your specific questions:

1. ARR works with URL rewrite for inspecting the incoming HTTP requests, but it's not just a proxy. It does manage a server farm (http://learn.iis.net/page.aspx/485/define-and-configure-an-application-request-routing-server-farm/) and comes with load balance alogirhtms, health monitoring, affinity, etc.

2. Not sure if I fully understand your question, but hopefully my statement above on managing the server farm provides more information.

3. This is one of the differences that I've described above. NLB is a "peer-to-peer" technology where you would create one VIP between the two machines and the NLB roles are enabled directly on those two machines. For ARR, it is proxy based and you will want to have another server in front of the "server farm".

4. ARR is an IIS Extension for IIS7/IIS7.5 (R2) that is designed to provide high availability and scalability. You can find more information on ARR at http://learn.iis.net/page.aspx/489/using-the-application-request-routing-module/.

Re: About ARR load balancing

JaroDunajsky — Thu, 18 Jun 2009 07:27:30 GMT

Have you seen the following link: http://learn.iis.net/page.aspx/511/achieving-high-availability-and-scalability---arr-and-nlb/ ? It describes quite well the ARR and NLB relationship

About ARR load balancing

_chill — Thu, 18 Jun 2009 05:27:39 GMT

Hi all,

I'm new here, and my project wanna load balancing the web server with two IBM x3650 that using Windows NLB. With the new IIS7, my advisor told me I can using the ARR technology to balancing the network load, but I found that just only rewirte the URL to anonter content server, its cannot balancing the real server load. I have some question about ARR.

1. ARR just rewrite the URL then forward to another content server, isnt right?

2.If ARR server can provding IIS 7 service as possible as a Web farm server?

3.Our environment just have 2 IBM x3650 as the front web server, so I think I can install the ARR on those two servers then build a server farm, whatever one server is crashed, another server will always providing service?

4.ARR is a new load balancing technology, just like Windows NLB, that can load balancing the server load?

forgive my bad english skill, thanks!

Joshua.