Network Load Balancing (WLBS) and virtual machines

By ramon

We where having trouble configuring a new network load balancing (WLBS) cluster. We have several host machines that each run a guest where all guests should be part of one cluster.

We started by preparing the first guest:

  • Created diskimages
  • Installed the os
  • Installed software
  • Updated all software
  • Shutdown


We now have a virtual machine and then

  • Copied it to all host machines
  • Started all guest
  • Add all guest to a domain


This is where weird behavior started to occur as some guest could not communicate and worst of all we could not create a network load balancing cluster with the network load balancing manager.

Turns out that all guests shared the same SID and NIC id’s. We forgot to

  • Run SysInternal’s NewSid tool on each guest to reset the SID
  • Remove the virtual NIC’s and re-adding them to reset the NIC id’s.


A bit of information can be found at the following knowledge base article:

Network Load Balancing Manager does not work with imaged servers

No interfaces are available for installing a new cluster

So what is the lesson learned? That after copying a virtual machine to remove all NIC’s at first startup, rebooting AND then running NewSid BEFORE adding the guest to a domain. I knew about the SID issues as I experienced similar behavior in the old days when you created Ghost images and restored them on several machines but what is new for me is the NIC stuff.

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