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Intermittent Hyper-V Switch Failure RRS feed

  • Question

  • Today is the third time in five months I've had this issue, and any help is appreciated.

    Hyper-V Host HV1 has two VMs, DC1 and APP1.  DC1 and APP1 use a Hyper-V switch to connect to the LAN.  Host and VMs are on the same subnet.  

    Sporadically, the guests lose the connection, cannot ping each other, or the host, or their default gateway.  

    The only solution I have found that works is to shut down the VMs, remove the virtual network adapter, delete the Hyper-V Switch, then build a new Hyper-V Switch using the same NIC on the host (the host only has two on board NICs, plus iDrac.)  Then assign that to each VM and boot the guests to their OS.  That works, but it then crumps again a few weeks later.  

    Tidbits: DC1 is Gen1 VM, while APP1 is Gen2 (DC1 is Server 2003, if that matters... Don't ask why, it's a long story... and APP1 is Server 2012 R2 Standard).  
    Host is Server 2012 R2 Standard
    HV Manager is 6.3.9600.16384
    Host is up to date on firmware from vendor website
    Host is fully patched with OS updates
    Dell's built in hardware diagnostics show no problems.

    I can get log files, if you wish.  

    Any help or ideas is _greatly_ appreciated.

    Best, 

    Jeff

    Thursday, November 7, 2019 11:11 PM

Answers

All replies

  • Hi,

    Try disabling VMQ on server's network adapters. Also ensure that server is up to date (has all Windows and hardware vendor's updates installed).
    Set-NetAdapterVmq -Name "NIC 1" -Enabled $False
    Set-NetAdapterVmq -Name "NIC 2" -Enabled $False
    Be sure that any power savings in the NIC driver is disabled.
    Server NIC drivers have power savings settings, and some enable it by default but the driver pays attention to the management OS NIC activity, not the hypervisor.

    For more information, please see here:

    https://support.microsoft.com/en-us/help/2986895/virtual-machines-lose-network-connectivity-when-you-use-broadcom-netxt

    Best Regards,

    Daniel


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    Friday, November 8, 2019 6:35 AM
    Moderator
  • Thank you, I'll give those a try.

    Best,

    Jeff

    Friday, November 8, 2019 3:11 PM
  • You're welcome. 

    Good luck!


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    Monday, November 11, 2019 2:12 AM
    Moderator
  • Hi,
    This is Daniel and wish you all the best!
    Since you have not responded for a long time, we will temporarily archive this post.
    If the reply helped you, please remember to mark it as an answer.
    If you have any questions, please do not hesitate to contact us.
    Best Regards,
    Daniel

    Please remember to mark the replies as answers if they help.
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    Thursday, November 14, 2019 7:38 AM
    Moderator
  • That's fine.  It seems the suggested solution is working, but who knows for certain?  Had this happen in July, and a reboot of the host settled things down for a while, then it came back after a couple months.  

    Hopefully this fix is permanent.

    Thanks again for the advice.  I am indebted to you, sir. 

    Best,

    Jeff

    Thursday, November 14, 2019 3:00 PM
  • You're welcome.

    Please remember to mark the replies as answers if they help.
    If you have feedback for TechNet Subscriber Support, contact

    Friday, November 15, 2019 1:54 AM
    Moderator