Windows Network Load Balancing issue RRS feed

  • Question

  • I am setting up an NLB cluster on the network and are experiencing the following issue.

    This a 2 hosts cluster setup. Both servers are running Windows 2016. Each node has 2 NICs attached.

    I enabled NLB on the first node and created the NLB cluster using unicast. The configuration was error free. However, once the cluster was configured (without adding the 2nd node to it yet), the node lost its network connection. I checked the IP configuration and did see that the cluster VIP is added to the NIC. The other issue is I didn't see the virtual MAC address (starts with 02:BF) assigned to the NIC. I can only see the original MAC for the NIC and NLB interfaces.

    I could not add the 2nd node to the cluster based on the issues above. Any idea?


    Monday, June 11, 2018 4:15 PM

All replies

  • By the way, the status of the cluster is converged. No obvious error from NLB in event viewer.
    Monday, June 11, 2018 10:50 PM
  • Hi,

    I am currently performing research on this issue and will get back to you as soon as possible. I appreciate your patience.

    If you have any updates during this process, please feel free to let me know.

    Best regards,


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    Tuesday, June 12, 2018 3:56 PM
  • Thanks,

    Things that I tried but not working are.

    Disabled the Windows firewall.

    Disabled all network protocol except IPV4.

    The interesting part is the unicast MAC address is not assigned to the cluster interface even the status of the cluster shown as converged and the host status is enabled.

    • Proposed as answer by Joop Idema Thursday, October 11, 2018 7:52 AM
    • Unproposed as answer by Joop Idema Thursday, October 11, 2018 7:52 AM
    Tuesday, June 12, 2018 9:10 PM
  • It is a bug that has been around since 2016!!

    I had the same problem on two Windows 2016 NLB unicast clusters. Both had the same problem. The NLB MAC address is not automatically changed.

    Just manually override de MAC address on the NLB adapters, with the correct 02-bf MAC address, and it works.

    Thursday, October 11, 2018 7:56 AM