NDIS_ENCAPSULATED_PACKET_TASK_OFFLOAD structure (ntddndis.h)

  • Article

The NDIS_ENCAPSULATED_PACKET_TASK_OFFLOAD structure contains the offload support state for Network Virtualization using Generic Routing Encapsulation (NVGRE) Task Offload (NVGRE-TO). This structure is used in the EncapsulatedPacketTaskOffloadGre member of the NDIS_OFFLOAD structure.

Syntax

typedef struct _NDIS_ENCAPSULATED_PACKET_TASK_OFFLOAD {
  ULONG TransmitChecksumOffloadSupported : 4;
  ULONG ReceiveChecksumOffloadSupported : 4;
  ULONG LsoV2Supported : 4;
  ULONG RssSupported : 4;
  ULONG VmqSupported : 4;
  ULONG UsoSupported : 4;
  ULONG Reserved : 8;
  ULONG MaxHeaderSizeSupported;
} NDIS_ENCAPSULATED_PACKET_TASK_OFFLOAD, *PNDIS_ENCAPSULATED_PACKET_TASK_OFFLOAD;

Members

TransmitChecksumOffloadSupported

Task offload settings for transmit checksum.

ReceiveChecksumOffloadSupported

Task offload settings for receive checksum.

LsoV2Supported

Task offload settings for large send offload version 2 (LSOv2).

RssSupported

Task offload settings for receive side scaling (RSS).

VmqSupported

Task offload settings for virtual machine queue (VMQ).

UsoSupported

Task offload settings for UDP segmentation offload (USO).

Reserved

Reserved for system use.

MaxHeaderSizeSupported

This member should be set to the maximum header size from the beginning of the packet to the beginning of the inner TCP or UDP payload (the last byte of TCP or UDP inner header) that the NIC must support for all of these task offloads. The protocol driver is expected to not offload processing of a packet whose combined encapsulation headers exceed this size.

Note: 256 bytes is a good default value that should cover all possible cases.

Remarks

In the initial capability advertisement and in NDIS_STATUS_TASK_OFFLOAD_CURRENT_CONFIG and NDIS_STATUS_TASK_OFFLOAD_HARDWARE_CAPABILITIES status indications, the TransmitChecksumOffloadSupported, ReceiveChecksumOffloadSupported, LsoV2Supported, RssSupported, VmqSupported, and UsoSupported members can be set to a bitwise OR of the following flags:

Term Description
NDIS_ENCAPSULATED_PACKET_TASK_OFFLOAD_NOT_SUPPORTED Specifies that the miniport adapter does not support the corresponding task offload feature that the member specifies.
NDIS_ENCAPSULATED_PACKET_TASK_OFFLOAD_INNER_IPV4 Specifies that the miniport adapter supports the corresponding task offload feature that the member specifies where the inner IP header of an encapsulated packet is IPv4.
NDIS_ENCAPSULATED_PACKET_TASK_OFFLOAD_OUTER_IPV4 Specifies that the miniport adapter supports the corresponding task offload feature that the member specifies where the outer IP header of an encapsulated packet is IPv4.
NDIS_ENCAPSULATED_PACKET_TASK_OFFLOAD_INNER_IPV6 Specifies that the miniport adapter supports the corresponding task offload feature that the member specifies where the inner IP header of an encapsulated packet is IPv6.
NDIS_ENCAPSULATED_PACKET_TASK_OFFLOAD_OUTER_IPV6 Specifies that the miniport adapter supports the corresponding task offload feature that the member specifies where the outer IP header of an encapsulated packet is IPv6.

As an example, if a miniport adapter and driver only support an IPv6 header as outer IP header but not as inner IP header, it will set TransmitChecksumOffloadSupported, ReceiveChecksumOffloadSupported, LsoV2Supported, RssSupported, VmqSupported, and UsoSupported to the value of the bitwise OR of NDIS_ENCAPSULATED_PACKET_TASK_OFFLOAD_INNER_IPV4, NDIS_ENCAPSULATED_PACKET_TASK_OFFLOAD_OUTER_IPV4 and NDIS_ENCAPSULATED_PACKET_TASK_OFFLOAD_OUTER_IPV6.

Regarding IP options and TCP options, the following assumption was made for encapsulated packets:

  • If the NIC specifies IpOptions and TcpOptions support in normal checksum offload and LSOv2 advertisement, it must support the option processing for encapsulated packets if Network Virtualization using Generic Routing Encapsulation (NVGRE) Task Offload is supported. This means it will support both inner and outer IP options and TCP options inside the encapsulated packets. There is no separate capability advertisement for these specific to only NVGRE Task Offload.

It is possible for a protocol driver to offload "mixed mode" packets which means packets in which the inner and outer IP header versions are different. For example, a packet could have outer IP header as IPv6 and the inner IP header as IPv4.

Requirements

Requirement Value
Minimum supported client Windows 8,Supported in NDIS 6.30 and later.
Minimum supported server Windows Server 2012
Header ntddndis.h (include Ndis.h)

See also