NDIS_SWITCH_FORWARDING_DESTINATION_ARRAY structure (ndis.h)

Article
05/26/2021

The NDIS_SWITCH_FORWARDING_DESTINATION_ARRAY structure specifies an array of Hyper-V extensible switch destination ports for a packet. Each element in the array is formatted as an NDIS_SWITCH_PORT_DESTINATION structure.

This information is contained in the out-of-band (OOB) data of the packet's NET_BUFFER_LIST structure.

Syntax

typedef struct _NDIS_SWITCH_FORWARDING_DESTINATION_ARRAY {
  NDIS_OBJECT_HEADER Header;
  UINT32             ElementSize;
  UINT32             NumElements;
  UINT32             NumDestinations;
  PVOID              FirstElement;
} NDIS_SWITCH_FORWARDING_DESTINATION_ARRAY, *PNDIS_SWITCH_FORWARDING_DESTINATION_ARRAY;

Members

Header

The type, revision, and size of the NDIS_SWITCH_FORWARDING_DESTINATION_ARRAY structure. This member is formatted as an NDIS_OBJECT_HEADER structure.

The Type member of Header must be set to NDIS_OBJECT_TYPE_DEFAULT. To specify the version of the NDIS_SWITCH_FORWARDING_DESTINATION_ARRAY structure, the Revision member of Header must be set to the following value:

NDIS_SWITCH_FORWARDING_DESTINATION_ARRAY_REVISION_1

Original version for NDIS 6.30 and later.

Set the Size member to NDIS_SIZEOF_NDIS_SWITCH_FORWARDING_DESTINATION_ARRAY_REVISION_1.

ElementSize

A ULONG value that specifies the size, in bytes, of each NDIS_SWITCH_PORT_DESTINATION element that follows the NDIS_SWITCH_FORWARDING_DESTINATION_ARRAY structure.

NumElements

A ULONG value that specifies the total number of NDIS_SWITCH_PORT_DESTINATION elements in the NDIS_SWITCH_FORWARDING_DESTINATION_ARRAY structure.

The value of the NumElements member specifies the number of currently used NDIS_SWITCH_PORT_DESTINATION elements (as specified by the NumDestinations member) plus the number of elements that are available for new destination ports. The number of unused NDIS_SWITCH_PORT_DESTINATION elements in the NDIS_SWITCH_FORWARDING_DESTINATION_ARRAY structure is calculated by (NumElements - NumDestinations).

NumDestinations

A ULONG value that specifies the number of NDIS_SWITCH_PORT_DESTINATION elements in the NDIS_SWITCH_FORWARDING_DESTINATION_ARRAY structure that specify port destinations.

Note If NumElements is set to zero, this member is ignored.

FirstElement

A pointer to the first NDIS_SWITCH_PORT_DESTINATION element in the buffer that contains the NDIS_SWITCH_FORWARDING_DESTINATION_ARRAY structure and all its elements.

Remarks

The extensible switch extension can do the following with the destination ports in a packet's NET_BUFFER_LIST structure:

Query the current destination ports on the extensible switch that the packet will be forwarded to.
The extensible switch extension calls the GetNetBufferListDestinations function to obtain the array of port destinations for a packet. GetNetBufferListDestinations returns a pointer to the NDIS_SWITCH_FORWARDING_DESTINATION_ARRAY structure in the Destinations parameter.

For more information, see Querying a Packet's Extensible Switch Destination Port Data.
Add or modify the destination ports for the packet.
After it queries the current destination ports for the packet, the extensible switch extension can do the following:
- A forwarding extension can add new destination ports to the NDIS_SWITCH_FORWARDING_DESTINATION_ARRAY structure.
- A filtering or forwarding extension can modify the data within an NDIS_SWITCH_PORT_DESTINATION structure for a destination port.
  Note A filtering extension can only change the IsExcluded member of this structure. A forwarding extension can also change the PreserveVLAN and PreservePriority members.
If the extension adds or modifies port destinations, it must call UpdateNetBufferListDestinations to commit the changes to the destination ports to the packet's OOB data in the NET_BUFFER_LIST structure.
For more information, see Managing Hyper-V Extensible Switch Destination Port Data.

Extensible switch extensions can use the NDIS_SWITCH_PORT_DESTINATION_AT_ARRAY_INDEX macro to access NDIS_SWITCH_PORT_DESTINATION elements in an NDIS_SWITCH_FORWARDING_DESTINATION_ARRAY array.

Requirements

Requirement	Value
Minimum supported client	Supported in NDIS 6.30 and later.
Header	ndis.h (include Ndis.h)