Virtual Networking Problems With Emulex NICs And Windows Server 2012 R2

Unfortunately, problems have arisen with WS2012 R2 Hyper-V networking where Emulex NICs are used. Hans Vredevoort (Hyper-V MVP) and Marc van Eijk (Azure MVP) have been experiencing this issue and blogged about it on  It appears that lots of you have encountered the same problem with VMs and virtual NICs losing connectivity when a virtual switch is connected to an Emulex NIC – in the guys’ case in HP blades with FlexFabric.

The core issue seems to be related to Emulex 10 GbE NICs – As they guys report in their post Kristian Nese (System Center MVP) also sees the problem on IBM servers with Emulex NICs.

There is no fix. Please watch the thread on to keep up with updates.

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5 Comments on Virtual Networking Problems With Emulex NICs And Windows Server 2012 R2

  1. It’s not only limited to Emulex, there are also Issues with some of the Intel and Broadcom 10GbE NICs.

  2. Ouch. I’m in the process of planning several Hyper-V 2012 R2 clusters, with 20+ hosts using IBM x3650 M4 servers with… Emulex 10GbE NICs. System design includes Teaming and full-converged network architecture (several vNICs).
    Time for me to contact the TAM to put pressure on this…

  3. Hayden Fitzgerald // February 14, 2014 at 12:03 AM // Reply

    Hi Aidan,
    We are currently tracking this issue with HP and have been given a beta copy of the updated Emulex NIC driver. I will pass on the results of the testing.


  4. Joerg Maletzy // February 19, 2014 at 8:52 AM // Reply

    Only for the record: HP released new Emulex NIC drivers for Windows Server 2012 R2 on Febuary 18, 2014


  5. Joerg Maletzy // February 19, 2014 at 8:55 AM // Reply

    One more comment: One workaround that helped us, was to disable encapsulated packet task offload per Disable-NetAdapterEncapsulatedPacketTaskOffload cmdlet

    You can check it per Get-NetAdapterEncapsulatedPacketTaskOffload cmdlet.


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