Windows Server NLB stopped working after migrating to vSphere 6.7

[Ivanildo_GalvÃ_]

Hello friends,

We have a VMware vSphere 6.5 environment with 10 servers on an IBM PureFlex Blade. In this environment we have some Windows Server 2012 virtual machines, with Microsoft NLB configured, IIS with ARR, everything working fine.

So we created a new environment with new Dell servers, Dell S4128-F ON SFP+ switches, with vSphere 6.7.

We migrated the virtual machines to this new environment, so NLB stopped working, the IP doesn't respond, the ping doesn't work, the machines respond by the IP of the network interface, but not by the NLB's virtual IP, even though they are on the same host ESXi, ie without using physical switches. If we return the virtual machines to the vSphere 6.5 environment, everything goes back to normal.

Does anyone have any idea what it might be? Switches? ESXi 6.7 ?

Any adjustments that need to be made?

Thanks !

[fabio1975]

Ciao,

How is configured your NLB, UNICAST or MULTICAST?

Depending on the infrastructure (UNICAST or MULTICAST) there are different configurations to be made indicated by VMWARE
You checked these links:

Microsoft NLB not working properly in Unicast Mode (1556) (vmware.com)

Sample Configuration - Network Load Balancing (NLB) Multicast Mode Configuration (vmware.com)

[Ivanildo_GalvÃ_]

Is multicast.

I read this links, no solution.

[Ivanildo_GalvÃ_ · Accepted solution]

Hi,

The problem is the switch Dell S4128-F ON, your firmware version don't work with Microsoft NLB.

Then is necessary firmware upgrade.

The Dell support confirm this information.