Here is some useful content when deploying Windows Network Load Balancing “NLB” within your Virtual Machines, especially when they are clustered and highly available.
To be able to use Windows NLB (Network Load Balancing) within Virtual Machines – based on Hyper-V – you must enable “Enable spoofing of MAC addresses”. For getting more details around the reason for this and the configuration please check out the following cluster team blog post:
Deploying Network Load Balancing (NLB) and Virtual Machines on Windows Server 2008 R2
Due to the fact that I see very often the issue, that NLB nodes (VM) does loose their “Enable spoofing of MAC addresses” setting after they are migrated to an different node in a failover cluster environment, I want to remember again, that you always should/must use Failover Cluster console when you changing any VM settings. otherwise the cluster service is not aware of your changes and those will not be migrated to the next node during next move.
Refresh the Configuration of a Virtual Machine
Update-ClusterVirtualMachineConfiguration –name “VMNAME”
NOTE: within your VMs, If you face issues with NLB like a.e. does not converge as expected or BSOD with an “STOP: 0x000000E1 (parameter1, parameter2, parameter3, parameter4)”, please checkout KB953828
Windows Server 2008 Hyper-V virtual machines generate a Stop error when NLB is configured or when the NLB cluster does not converge as expected