FAQ Week for NLB: Friday

Every day this week the Clustering & High-Availability is writing about some of the top questions we get about Network Load Balancing (NLB) in Windows Server 2008 R2.  We hope you find these helpful!

·         Monday: http://blogs.msdn.com/b/clustering/archive/2010/07/20/10040072.aspx

·         Tuesday: http://blogs.msdn.com/b/clustering/archive/2010/07/20/10040467.aspx

·         Wednesday: http://blogs.msdn.com/b/clustering/archive/2010/07/21/10041067.aspx

·         Thursday: http://blogs.msdn.com/b/clustering/archive/2010/07/22/10041612.aspx

Gary Jackman

Software Test Engineer

Network Load Balancing

Microsoft

Does NLB detect the health or availability of the application it is directing traffic to?

No, for simplicity, NLB is designed to be unaware of any application being hosted on the cluster.  For monitoring application health you will need to use a SCOM Management Pack, 3^rd party tool, or write your own monitoring tool that checks your application and controls NLB appropriately.

Refer to nlbmon.vbs for an example of a custom management utility.  While it does not adjust the node weights, it does stop and start NLB on the nodes based on workload health.  More information: http://msdn.microsoft.com/en-us/library/cc307934(VS.85).aspx

We added health monitoring capability in the SCOM Management Pack specifically for IIS via an IIS-NLB integrated MP. Here is some information on that:

·         http://blogs.msdn.com/clustering/archive/2008/06/24/8648702.aspx

·         http://blogs.msdn.com/clustering/archive/2009/04/28/9572859.aspx

·         http://www.microsoft.com/downloads/details.aspx?FamilyId=78D8C93A-BAE6-4C5D-90AF-B0BF2CE12998&displaylang=en&displaylang=en

Does NLB support multi-homed web servers?

Yes.  You can bind multiple IP addresses to multiple virtual web sites and still use NLB to load balance traffic between them.  Refer to the port rule question on Wednesday’s FAQ for more information.