NIC Teaming
As more resources are consolidated onto a smaller number of physical systems, it’s
critical that those consolidated systems are as reliable as possible. Previously in this
chapter, we created virtual switches, some of which were external to connect to a
physical network adapter. Many virtual machines connect to a virtual switch for their
network access, which means that a network adapter failure in the host would break
connectivity for a large number of virtual machines and the workloads running within
them. It is therefore important to provide resiliency from network adapter failure and
potentially enable aggregation of bandwidth from multiple network adapters. For
example, a solution would be to group four 1Gbps network adapters together for a
total bandwidth of 4Gbps.
The ability to group network adapters together, made possible by a feature known as
NIC Teaming, has been a feature of many network drivers for a long time. However,
because it was a feature of the network driver, the implementation differed by vendor.
It was not possible to mix network adapters from different vendors, and strictly
speaking, the technology was not “supported” by Microsoft because it was not
Microsoft technology.
Windows Server 2012 changed this by implementing NIC Teaming as part of the
operating system itself. It allows up to 32 network adapters to be placed in a single
NIC team, and the network adapters can be from many different vendors. It’s
important that all of the NICs are the same speed, because the Windows NIC Teaming
algorithms do not consider NIC speed as part of their traffic-balancing algorithms. If
you mixed 1Gbps network adapters with 10Gbps network adapters, the 1Gbps network
adapters would receive the same amount of traffic as the 10Gbps network adapters,
which would be far from optimal.
NIC Teaming is simple to configure via Server Manager or PowerShell. For example,
the following command creates a new NIC team using Switch Independent mode,
the dynamic load-balancing algorithm, and two network adapters:
New-NetLbfoTeam -Name "HostSwitchTeam" -TeamMembers NICTeam3,NICTeam4 -TeamingMode SwitchIndependent -LoadBalancingAlgorithm Dynamic
-Confirm:$false
Additionally, as you saw earlier in the chapter, SCVMM can automatically create
teams on hosts when deploying logical switches. A NIC team has two primary
configurations (in addition to specifying which network adapters should be in the
team): the teaming mode and the load-balancing algorithm. There are three teaming
modes:
Static Teaming Configuration is required on the switches and computer to
identify links that make up the team.
Switch Independent Using different switches for each NIC in the team is not