INF Requirements for Hyper-V Extensible Switch Extensions

Hyper-V extensible switch extensions are developed as NDIS filter drivers. As a result, the INF requirements for extensions are based on the INF requirements for all NDIS filter drivers. When you create an INF file for an extensible switch extension, you should use the INF settings for a modifying or monitoring filter driver. For more information on these settings, see INF File Settings for Filter Drivers.

In addition, you must follow these guidelines for INF files for extensible switch extensions:

• An extensible switch extension must be installed as a modifying filter driver.

  For more information on the INF requirements for a modifying filter driver, see Configuring an INF File for a Modifying Filter Driver.

  Note An extension with a filter class of ms_switch_capture can perform the same tasks as a monitoring filter driver. For more information, see Types of Filter Drivers.

• The FilterMediaTypes entry in the filter INF file defines the driver's bindings to other drivers and interfaces. The FilterMediaTypes entry for an extensible switch extension must include the vmnetextension value. This value specifies a binding to the extensible switch extension miniport adapter.

  The FilterMediaTypes entry allows a comma-delimited list of media types to be specified. This allows the extension to be bound to a physical interface or to the extensible switch interface.

  The following example shows a FilterMediaTypes entry that allows an extension to be bound to either the physical Ethernet network adapter or an extensible switch virtual network adapter.

  HKR, Ndi\Interfaces, FilterMediaTypes, , "ethernet, vmnetextension"
  

  If the FilterMediaTypes entry only specifies the vmnetextension value, the extension will only bind to the driver stacks for all extensible switches on the system.

  If the FilterMediaTypes entry specifies vmnetextension as well as other media types, the extension can determine whether it is bound within an extensible switch driver stack by calling NdisFGetOptionalSwitchHandlers. If the function returns NDIS_STATUS_SUCCESS, the extension is bound within the extension driver stack. If the function returns NDIS_STATUS_NOT_SUPPORTED, the extension is bound within the driver stack for a different physical network interface.

  For more information about the FilterMediaTypes entry, see Intermediate Driver UpperRange And LowerRange INF File Entries.

• The FilterClass value in the INF file for an extension determines its order in a stack of filters. The FilterClass entry must contain one of the values from the following table.

  FilterClass value	Description
  ms_switch_capture	An extension of this class monitors packet traffic. However, this class of extension cannot apply port policies or alter destination ports for a packet. For more information about this class of extension, see Capturing Extensions.
  ms_switch_filter	An extension of this class filters packet traffic and enforces port or switch policy for packet delivery through the extensible switch. This class of driver can also inspect and remove destination ports for each packet based on policy settings. For more information about this class of extension, see Filtering Extensions.
  ms_switch_forward	An extension of this class has the same capabilities as the ms_switch_filter class. This class of extension can also forward packets to other extensible switch ports, as well as inject packet traffic to any extensible switch port. On the ingress data path, this class of extension is invoked after the ms_switch_filter class of extension. On the egress data path, this class of extension is invoked before the ms_switch_filter class of extension. For more information about this class of extension, see Forwarding Extensions. Note Only one extension of this class is allowed in the extensible switch driver stack.

When the extension is installed with these INF settings, it will be configured to bind to every extensible switch instance. However, the binding will be disabled and must be explicitly enabled through a PowerShell cmdlet. For more information on this procedure, see Enabling Hyper-V Extensible Switch Extensions.