NetFT Virtual Adapter Performance Filter

First published on MSDN on May 27, 2016

In this blog I will discuss what the NetFT Virtual Adapter Performance Filter is and the scenarios when you should or should not enable it.

The Microsoft Failover Virtual Adapter (NetFT) is a virtual adapter used by the Failover Clustering feature to build fault tolerant communication routes between nodes in a for intra- communication.

When the Cluster Service communicates to another node in the cluster, it sends data down over TCP to the NetFT virtual adapter.  NetFT then sends the data over UDP down to the physical card, which then sends it over the to another node.  See the below diagram:


When the data is received by the other node, it follows the same flow.  Up the physical adapter, then to NetFT, and finally up to the Cluster Service.  The NetFT Virtual Adapter Performance Filter is a filter in 2012 and 2012 R2 which inspects traffic inbound on the physical NIC and then reroutes cluster traffic addressed for NetFT directly to the NetFT driver.  This bypasses the physical NIC UDP / IP stack and delivers increased cluster performance.

When to Enable the NetFT Virtual Adapter Performance Filter

The NetFT Virtual Adapter Performance Filter is disabled by default.  The filter is disabled because it can cause issues with Hyper-V clusters which have a Guest Cluster running in VMs running on top of them.  Issues have been seen where the NetFT Virtual Adapter Performance Filter in the host incorrectly routes NetFT traffic bound for a guest VM to the host.  This can result in communication issues with the guest cluster in the VM.  More details can be found in this article:


https://support.microsoft.com/en-us/kb/2872325


If you are deploying any workload
other
than Hyper-V with guest clusters, enabling the NetFT Virtual Adapter Performance Filter will optimize and improve cluster performance.

Windows Server 2016

Due to changes in the networking stack in Windows , the NetFT Virtual Adapter Performance Filter has been removed.

Thanks!

Elden Christensen

Principal PM Manager

High-Availability & Storage

Microsoft

 

This article was originally published by Microsoft’s Failover Clustering Blog. You can find the original article here.