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Windows Server 2008 R2 Thread, Network issue on Hyper-v in Technical; Hi Having some strange network issue on one of our hyper-v hosts its seems very random times and very intermittent, ...
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    Network issue on Hyper-v

    Hi
    Having some strange network issue on one of our hyper-v hosts

    its seems very random times and very intermittent, so there is no set pattern.

    I get loads of event ID 25
    The MAC address '00-15-5D-EC-83-20' has moved from port 'E35A4EF3-742D-458B-AC3E-2693D82C9502' to port 'F2D4301C-0BAA-4B04-A14E-2C6DAA84ED08'

    then it drops the network, this is causing loads of issues because the VHD's are hosted on a Iscsi device and the VMs just stop

    The server has 2 onboard and a dual nic card installed, the host machine is running on one of the onboard nics and the 2 vm's are running on the dual card using a port each.

    I have looked around the web and found various things to try, including enabling mac spoofing and recreating the virtual adapters in the virtual virtual network manager.
    But to no avail, anybody out there have any suggestions its starting to get very annoying

    cheers

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    by default dosent hyperv give each nic a dynamic mac address so presumably something is forcing that to change try inputting a mac manually see if theat helps

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    wickit's Avatar
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    Hi yes it does, and should have mentioned I have tried both manual and auto mac, again with no avail

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    What type of Network Adapter are your VMs set up with? Synthetic is best, emulated is not as robust - the problem I found was that live migrating a VM with an emulated NIC would result in pings being lost after migration as the ARP tables were never updated, switched to synthetic and it work beautifully.

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    zag
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    If you are running windows 2008 R2 then there is a patch for "lost network on high load" to fix this.

    I've found all my hyper-v hosts needed this.

    Quick Google found this, not sure if its the correct

    http://support.microsoft.com/kb/2263829
    Last edited by zag; 25th February 2013 at 12:26 PM.

  6. 2 Thanks to zag:

    tmcd35 (25th February 2013), wickit (25th February 2013)

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    Quote Originally Posted by zag View Post
    If you are running windows 2008 R2 then there is a patch for "lost network on high load" to fix this.

    I've found all my hyper-v hosts needed this.

    Quick Google found this, not sure if its the correct

    The network connection of a running Hyper-V virtual machine may be lost under heavy outgoing network traffic on a computer that is running Windows Server 2008 R2 SP1

    great stuff will try this tonight and see how we go

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    Quote Originally Posted by zag View Post
    If you are running windows 2008 R2 then there is a patch for "lost network on high load" to fix this.

    I've found all my hyper-v hosts needed this.
    I think that explains some issues I'd been having with VM's lately! I went for the more drastic "upgrade to 2012" solution. So far it's working

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    OK this patch was a no go, it refused to run saying wrong OS
    Im running windows server 2008 r2 Datacenter

    back to square one !
    DOH

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    Quote Originally Posted by tmcd35 View Post
    I think that explains some issues I'd been having with VM's lately! I went for the more drastic "upgrade to 2012" solution. So far it's working
    I have to agree, they stuffed the network stack in 2008r2 they never fixed the vm memory mapper and power state issues properly. Just ditch it and go 2012.

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    zag
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    Quote Originally Posted by SYNACK View Post
    I have to agree, they stuffed the network stack in 2008r2 they never fixed the vm memory mapper and power state issues properly. Just ditch it and go 2012.
    Since running that patch, I've not had any network issues on virtual machines.

    Before that the virtual machine just used to loose network connection randomly after a couple of months. Was very weird and certainly not just on high load.

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    Quote Originally Posted by zag View Post
    Since running that patch, I've not had any network issues on virtual machines.

    Before that the virtual machine just used to loose network connection randomly after a couple of months. Was very weird and certainly not just on high load.
    It could not cope with TMG, patch or not, not high load but lots of small packets which chewed it badly.

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