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Wednesday, March 13, 2013

Slow Network Performance When Using NIC Teaming in Windows Server 2012 Hyper-V


Couple day ago, I’ve deployed a new Windows Server 2012 Hyper-V into a production environment and one of the my design requirement is configure NIC Teaming using Windows Server 2012.

My scenario:-

  • DELL R720
  • 8 NIC Card – 1Gbps. (4 Broadcom and 4 Intel NIC)

Well, everything work well with NIC Teaming properly configure with virtual switch created on the NIC Teaming. But one of the problem detected is Virtual machine which bind to the NIC Teaming having slow performance when copying and reading file share.

Therefore, I’m using a freeware tool called “Lan Speed Test” to test read/ write in the VM. The result came out very bad. I just perform read/write 20Mbps to a file server. The speed that I got is estimated 1 Mbps for both read/write and consider took a very long period to complete the whole process. (Feel free to use other test tool)


Repeat the same process on the entire VMs and some are getting good performance but few VMs is getting bad performance.

To isolate the problem, I have decided to break the teaming and create an individual virtual switch

  • Broadcom NIC –> 1 virtual switch
  • Intel NIC –> 1 virtual switch

Repeat the same test and found out the slow performance problem is only happen when using Broadcom NIC. I just do some tweak on “Disable Virtual Machine Queue”.


And test using the above tool. The result has improved to


Since the performance has improved and I’ve re-create the NIC teaming and virtual switch with “Virtual Machine Queue” disable on Broadcom NIC.

Now the performance result is faster.


  • Read/Write result is varies
  • Take note on time to complete.
  • Test small file (20Mbps) to get result on fast/slow