poor network when create virtual switch in hyper-v 2012


  • Hello,

    i installed on DELL R620 windows server 2012 STD and add the hyper-v role

    when i created a virtual switch , the speed of network in the HOST( the server itself) is ver poor ( copy file from fileserver is 300Kbs)

    when i remove the virtual switch , the speed of the network is better(  copy file from fileserver is 10-20Mbps)

    i spoke with DELL support center , and after check up , no problem has found.

    i tried all the chnges with the offload checksum etc but nothing helped

    Please your comment about this issue



    Monday, January 7, 2013 11:33 AM


All replies

  • Hi Dotan, 

    firmware and driver from the R620 are up to date? Which network daughtercards do you use? 

    Could you post the virtual switch configuration for us? 

    How does a VM perform on the NICs? 

    We have also a similar post in our TechCenter maybe this helps you:

    "The Broadcom NICs in this Dell server have a setting "Virtual Machine Queues" that defaults to enabled. Once disabled, the guest OS has the same network speed as the physical machine does."

    Using Virtual Machine Queues


    Monday, January 7, 2013 12:06 PM
  • Hi,

    How are things going? I just want to check the status of the issue. If you have any update or concern, please feel free to let us know.

    Best Regards,


    If you have any feedback on our support, please click here

    Aiden Cao
    TechNet Community Support

    Tuesday, January 15, 2013 2:30 AM
  • hello Florian,

    disable Virtual Machine Queues did the trick and solved my problem

    the NIC'S  OF THE r620 are Broadcom  , and as i understand it in SERVER 2008 this setting of the Queue should be enabled , so why in R620 and server 2012 to disable it? because of the brand? NIC vendor ? or OS (2012) ?



    Saturday, January 19, 2013 9:31 AM
  • Hi Dotan, 

    no it's because Microsoft removes chimney with Winserv 2012. So the que is no longer needed.



    Wednesday, January 30, 2013 12:45 PM
  • Hi All,

    I have a small setup of 2 x HyperV servers in a Workgroup connected to a single switch (1GB);

    Host 1 - Dell T320, Windows 2102, HyperV, on board Broadcom Dual NIC's teamed

    Host 2 - Dell T420, Windows 2012 R2, HyperV, on board Broadcom Dual NIC's teamed, Separate Dual Broadcom NIC's teamed.

    *all of the above Teamed in windows 2012 and HyperV

    Since enabling HyperV Switch the network is really slow and having problems RDP and copying files directly from host1 to host2. or anything outside the 2 hosts.

    I have disabled as sugguested the VMQ on all NIC's and in the Teams in both hosts but its still very slow copying files between hosts is like 3mbs.

    However, from host2 I can RDP fast to it's own hosted VM's and the VM's have fast RDP to the other Hosts and copy files is faster.

    While troubleshooting I I found if If I break the teaming its fast copying files at 200MBS host to host but RDP still struggles a bit host to host (sort of sticks determining / securing connection and 50/50 chance of connecting). Also slow when using IP6 to RDP from one host to another.

    Any idea what I should try next?



    Tuesday, April 15, 2014 2:17 PM
  • Need some additional information

    • Which Team type are you utilizing? 
    • Which Raid Controller are you using on the hosts?

    I would suggest you try this as well while its specific to 10Gb CNA's it can help with 1Gb in some cases.  SMB FILE COPY PERFORMANCE

    Also utilizing the low latency Bios settings can often offer additional NIC performance 

    Dell 12th Gen Low Latency Bios Settings


    Tuesday, April 15, 2014 2:35 PM
  • Thanks Sean i will given them a try.

    I am currently using the Windows 2012 Teaming (configured in Windows 2012 and not using the Broadcom utilities)

    I am using Perc710.

    The strange thing was when I broke the team the file copy went from 3mbs to 300mbs host1 to host2.


    Tuesday, April 15, 2014 2:54 PM
  • I would also make sure you have the latest FW and Driver for the 710 I have seen simular issues with that controller on older revisions. 

    The Teaming type along with the Teaming Mode can affect performance as well especially with 2012 NON R2 where Native teaming does not typically perform as well. 

    The links below have alot of good information on Native teaming and the diffrences along with which technologies are compatible with one another. 

    2012 Windows Nic Teaming

    2012 R2 Windows Nic Teaming

    Tuesday, April 15, 2014 3:32 PM
  • Just to update you all, my RDP and Network is fast now....

    The cause was because I ticked the "All managemnet operating system to share this network adapter" wounder like I said the issue happened after I setup the HyperV Switch....

    Happy days :)

    Tuesday, April 15, 2014 8:33 PM
  • Dear Hyper-V team,

            we are facing very horrible situation with hyper-v 2012 performance, we have installed hyperv 2012 on Dell R820 server and the performance is very bad, for the first hour everything is good, after sometime, i am facing network latency issue and i am getting more than 10 ms, i have seen lot many articles and blog to find out the issue but i could not, kindly help us to solve the problem.

    Dell team has connected the server through IDrac and they have even updated all the firmwares and drivers, still the same problem no improvement, kindly resolve asap.

    Tuesday, June 17, 2014 4:25 PM
  • Are you using broadcom drivers?

    I was and updated them to latest version and network performance would be OK for a while then get really slow and even stop responding. Spent 3 weeks with Dell and no joy. In the end I unteamed,  unistalled the Dell drivers, deleted the nic's from device manager, reboot and re-installed and been fine ever since and Dell call closed. Happy days :) 

    Tuesday, June 17, 2014 7:35 PM