After reboot, VMWare server in NLB cluster drops ping packets until NIC reset - slow app performance

Justin Price 41 Reputation points
2021-06-23T11:49:53.17+00:00

I have two Server 2019 vmWare virtual machines configured as NLB cluster hosts with IGMP Multicast. This has worked well for months. Then updates were turned on for both servers, and for the past few months the servers have been rebooted on a monthly basis.

Now, usually a few days after reboot, I'll get complaints from users that the web app is going slow. Sure enough, I'll start a ping on one of the two servers and one will be dropping tons of ping requests. If I stop the host on the cluster, disable/enable the virtual dedicated NLB NIC, then enable the server again on the cluster, the pings no longer drop and the app returns to normal speed. This will last until reboots happen again the next month.

This is not contained to either of the two servers and is entirely random. It can be one or the other and even both.

Logs from right around the reboot time/date start to alternate every 1-15 minutes between the below messages. These stop once I disable/enable the NIC:

NLB is initiating convergence on host 0x1 because host 0x2 is leaving the cluster. Event ID: 69

Host 0x1 converged with host(s): 1,2. It is now an active member of the NLB cluster and will start load balancing traffic as the default host. The default host is the host with the lowest host priority. It handles all traffic that isn't covered by any of the defined port rules. Event ID: 29

I'm no good with Wireshark, so don't know if packets are being dropped. Any idea what's going on here or how I can troubleshoot?

Windows Server 2019
Windows Server 2019
A Microsoft server operating system that supports enterprise-level management updated to data storage.
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Windows Network
Windows Network
Windows: A family of Microsoft operating systems that run across personal computers, tablets, laptops, phones, internet of things devices, self-contained mixed reality headsets, large collaboration screens, and other devices.Network: A group of devices that communicate either wirelessly or via a physical connection.
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Accepted answer
  1. Sunny Qi 10,896 Reputation points Microsoft Vendor
    2021-06-24T08:48:04.467+00:00

    Hi,

    Thanks for posting in Q&A platform.

    You issue is involving third-party production VMware which we're not familiar with, I would suggest asking over at the dedicated VMware forum over here:

    https://communities.vmware.com/#
    Please Note: Since the website is not hosted by Microsoft, the link may change without notice. Microsoft does not guarantee the accuracy of this information.

    For ping NLB cluster IP, please refer to the following similar thread discussed before:

    Unable to ping NLB cluster ip.

    Best Regards,
    Sunny

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