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NIC Teaming

System administrators and IT professionals are always looking for ways to improve network performance and fault tolerance. One method for achieving this reliability is for Windows-based systems is through NIC Teaming teaming on Windows Server editions.
Windows Server 2012 R2 Tutorials

What is NIC Teaming?

Network Interface Card (NIC) teaming allows you to combine multiple physical network adapters into a virtual NIC, which will then be presented to the OS as a single NIC. All of the traffic being sent from the OS will pass through the virtual NIC and be load-balanced across the assigned physical network connections. NIC teaming on Windows Server can support up to 32 physical connections per virtual NIC.

This ability offers System Administrators a simple solution for link aggregation and load balancing, failover and Software-Defined Networking (SDN). There are similar solutions available on certain hardware from third-party vendors but these are often limited to specific hardware. One of the benefits of Microsoft’s NIC teaming is that it is hardware and vendor-agnostic.

The Benefits of NIC Teaming

The benefits of NIC teaming stem from its load-balancing capabilities. Efficiently breaking up network traffic across multiple connections better utilizes network resources, ensures the availability of servers and increases bandwidth. It also helps simplify network configuration.

NIC Teaming Requirements for Virtual Machines

Before starting this process, there are a few NIC teaming requirements for virtual machines that will need to be in place. First, you will need access to either Windows Server 2012, 2012 R2, 2016 or 2019. You will also need at least two network adapters available. And finally, you’ll need to use the Microsoft Network Adapter Multiplexor to initiate NIC teaming.

NIC Teaming Modes

When you commence NIC Teaming, you’ll need to select what Teaming Mode to use. The Teaming Mode determines how the server and switch(es) will divvy up traffic between the multiple connections. There are three types of Teaming modes: Switch independent, Link Aggregation Control Protocol (LACP) and Static.

Switch Independent Mode

Switch Independent Mode allows you to connect users to multiple, non-stack switches. This is the only teaming mode that doesn’t require configuration changes on the connected switches. Switch Independent Mode uses media access control (MAC) addresses to control to which interface incoming data should be sent. 

Static Mode

Static Mode teaming requires you to manually configure the ports on the switch that connects with the NIC team into a Link Aggregation Group (LAG). In this mode, the server and the switch split traffic between all links connected to another device. The downside of this mode is that it doesn’t help isolate errors, such as incorrectly connected cables.


LACP Mode is similar to Static teaming, except it ensures each active cable in the link is connected to the intended LAG. In fact, it will not send any data through links that are not connected to the predetermined LAG.

What is Microsoft Network Adapter Multiplexor?

You may be wondering from the previous section on requirements, what is Microsoft Network Adapter Multiplexor? It’s a kernel mode driver consisting of a set of protocols that help simplify NIC Teaming by removing the need for any third-party utilities. The Microsoft Network Adapter Multiplexor is initialized when using two different connections to form one physical device to increase bandwidth or fault tolerance. 

Should the Microsoft Network Adapter Multiplexor Be Enabled?

The Microsoft Network Adapter Multiplexor can be found through the Wi-Fi properties windows under the “items this connection uses” list. It is typically disabled on computers by default. 

This is because enabling the Multiplexor while other items on this list are enabled will only lead to an error message:

Microsoft network adapter multiplexor protocol

Microsoft Network Adapter Multiplexor protocol is only used when combining network adapters into a virtual NIC. Windows Server editions are built with this awareness, so there’s no need to enable the Multiplexor manually. It will automatically enable when a NIC team connection is created.

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