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Working with NIC Teaming in Windows Server 2012

By Nirmal Sharma (Send Email)
Posted January 13, 2014


Of the many networking features introduced in Hyper-V 3.0 on Windows Server 2012, several were added to enhance the overall capability for networking virtual machines (VMs). One of the features introduced in Hyper-V 3.0 is a collection of components for configuring NIC teaming on virtual machines and the Windows operating system. Windows Server 2012 R2 Tutorials

Originally designed for Windows Server 2012, NIC Teaming can also be used to configure teamed adapters for Hyper-V virtual machines. Since our primary focus in this article is to provide an overview of NIC Teaming in Windows Server 2012 and later versions, we will not cover in detail the steps needed to configure NIC Teaming for operating systems and virtual machines.

In earlier versions of Hyper-V (version 1.0 and version 2.0), the Windows operating system did not provide any utility to configure NIC Teaming for physical network adapters, and it was not possible to configure NIC teaming for virtual machines. A Windows administrator could configure NIC teaming on Windows by using third-party utilities but with the following disadvantages:

  • Support was provided by the vendor and not by Microsoft.
  • You could only configure NIC Teaming between physical network adapters of the same manufacturer.
  • There are also separate management UIs for managing each third-party network teaming if you have configured more than one teaming.
  • Most of the third-party teaming solutions do not have options for configuring teaming options remotely.

Starting with Hyper-V version 3.0 on Windows Server 2012, you can easily configure NIC Teaming for Virtual Machines.

This article expounds on the following topics:

  • NIC Teaming Requirements for Virtual Machines
  • NIC Teaming Facts and Considerations
  • How NIC Teaming works

NIC Teaming Requirements for Virtual Machines

Before you can configure NIC Teaming for virtual machines, ensure the following requirements are in place:

  • Make sure you are running minimum Windows Server 2012 version as the guest operating system in Virtual Machine.
  • Available physical network adapters that will participate in the NIC Teaming.
  • Identify the VLAN number if the NIC team will need to be configured with a VLAN number.

NIC Teaming Facts and Considerations

It is necessary to follow several guidelines while configuring NIC Teaming, and there are also some facts you should keep in mind that are highlighted in bullet points below:

  • Microsoft implements a protocol called "Microsoft Network Adapter Multiplexor" (explained shortly) that helps in building the NIC Teaming without the use of any third-party utilities.
  • Microsoft's teaming protocol can be used to team network adapters of different vendors.
  • It is recommended to always use the same physical network adapter with the same configuration, including configuration speed, drivers, and other network functionality, when setting up NIC Teaming between two physical network adapters.
  • NIC teaming is a feature of Windows Server, so it can be used for any network traffic, including virtual machine networking traffic.
  • NIC teaming is set up at the hardware level (physical NIC).
  • By default, a Windows Server can team up to 32 physical network adapters.
  • Only two physical network adapters in teaming can be assigned to a virtual machine. In other words, a network teamed adapter cannot be attached to a virtual machine if it contains more than two physical network adapters.
  • NIC Teaming can only be configured if there are two or more 1 GB or two or more 10 GB physical network adapters.
  • Teamed network adapters will appear in the "External Network" configuration page of Virtual Machine settings.
  • NIC Teaming can also be referred to as NIC bonding, load balancing and failover or LBFO.

How Does NIC Teaming Work?

Microsoft developers have designed a new protocol for NIC Teaming specifically. The new protocol, known as Microsoft Network Adapter Multiplexor, assists in routing packets from physical network adapters to NIC teaming adapters and vice versa. This protocol is responsible for diverting the traffic from a teamed adapter to the physical NIC. The protocol is installed by default as part of the physical network adapter initialization for the first time.

The Microsoft Network Adapter Multiplexor protocol is checked in the teamed network adapter and unchecked in the physical network adapters that are part of the NIC Teaming. For example, if there are two physical network adapters in a team, the Microsoft Network Adapter Multiplexor protocol will be disabled for these two physical network adapters and checked in the teamed adapter as shown in the below screenshot:

NIC Teaming in Windows Server 2012

As shown in the above screenshot, the Microsoft Network Adapter Multiplexor protocol is unchecked in the properties section of the Physical Network Adapter named "PNIC5," and the Microsoft Network Adapter Multiplexor protocol is checked in the property of "Hyper-VTeaming" teamed network adapter. "Hyper-VTeaming" is a teamed network adapter.

Any network traffic generated from the teamed adapter will be received by one of the physical NICs participating in the Teaming. The teamed adapter talks to the Microsoft Network Adapter Multiplexor protocol bound in the physical NIC.

If this protocol is unchecked in one of the physical network adapters, then the Teamed adapter will not be able to communicate with the physical network adapters participating in the Teaming. Third-party teaming utilities might have a different protocol designed for this, but the one offered by Microsoft can be used with any vendor network card — so this protocol is vendor- and network adapter-independent.


Nirmal Sharma is a MCSEx3, MCITP and Microsoft MVP in Directory Services. He has specialized in Microsoft Technologies since 1994 and has followed the progression of Microsoft Operating System and software. In his spare time, he likes to help others and share some of his knowledge by writing tips and articles on various sites and contributing to Solution IDs for www.Dynamic-SpotAction.com. Nirmal can be reached at nirmal_sharma@mvps.org.

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