Solve these common NIC team problems in Hyper-V

Before you encounter noncompliant hardware, integrated security errors and configuration issues, read this expert advice so you know what to do when the time comes.

There are several common problems that can plague a Hyper-V network interface card team under Windows Server 2016....

Perhaps the most common problem is noncompliant hardware. For example, a Hyper-V NIC team depends on the proper use of address resolution protocols, such as the address resolution protocol in IPv4 or the neighbor discovery protocol in IPv6. Both of these protocols require that NICs receiving packets from the network must resolve the host or VM IP address to a media access control address.

However, not all NIC hardware -- a storage area network controller, for example -- implements address resolution properly by resolving an IP address to a MAC address through address resolution protocol or neighbor discovery protocol. This can potentially result in outgoing packets being sent to the wrong destination MAC address, causing the Hyper-V switch to drop packets. If packet captures reveal problems with address resolution, the noncompliant hardware device may need to be replaced with a conforming device.

A switch with integrated security features may present errors or warnings. This can occur when teamed traffic is received from the same IP address that includes different source MAC addresses -- the switch doesn't know that the incoming traffic is coming from a NIC team, but the differences in source MAC addresses can cause errors when the switch employs security tactics like dynamic address resolution protocol inspection. Check the switch logs. Security errors may suggest that the switch's own security features are blocking traffic from the NIC team. If so, the switch may need to be reconfigured to allow or disable those security features or be replaced with a more intelligent switch that supports such configurations.

Finally, administrators often encounter problems when configuring a Hyper-V NIC team in PowerShell. Specifically, the PowerShell commands Disable-NetAdapter and Enable-NetAdapter are used to disable a NIC team. This effectively removes the NIC team interface, so attempting to re-enable the NIC team doesn't work -- though all of the member NICs are re-enabled. Once the members are re-enabled, the team interface will be recreated, and administrators will need to manually re-enable the NIC team interface to restart network traffic through the team.

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