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Combining Types of Task Offloads

Last Updated: 9/2/2016

The following restrictions determine which combinations of NDIS 6.0 and later task offload services can be active on the system:

  • A task offload-capable miniport adapter can support checksum offload alone.

  • A large send offload version 1 (LSOV1)-capable network interface card (NIC) must support V4 TCP and IPv4 checksum transmit offload services. If an LSOV1-capable miniport adapter also supports Internet protocol security (IPsec) offload, NDIS will configure the adapter to offload either IPsec or LSOV1, but not both.

  • A large send offload version 2 (LSOV2)-capable miniport adapter must support TCP and IP Checksum transmit offload. If a LSOV2-capable miniport adapter also supports IPsec offload, NDIS will configure it to offload IPsec or LSOV2, but not both.

Miniport drivers are not required to support both IPv4 and IPv6. All NDIS 6.0 and later miniport drivers must support Ethernet 802.3 encapsulations with the ability to support Ethernet 802.1Q tags. The following table describes the hardware requirements when the miniport driver reports support for various offload capabilities.

Type of offloadIPv4IpV6

Checksum Offload

UDP Checksum

Optional

Optional

TCP Checksum

Optional

Optional

TCP Options

Optional

Required (for TCP Checksum)

IP Checksum

Optional

Not Applicable

IP Options

Required (for TCP checksum)

Not Applicable

IP Extension Header

Not Applicable

Required (128 bytes)

Large Send Offload version 1 (LSOv1)

Max Offload Size

<= 64K

Not Applicable

TCP Options

Required

Not Applicable

IP Options

Required

Not Applicable

Large Send Offload version 2 (LSOv2)

Max Offload Size

Unlimited

Unlimited

IP Options

Required

Required (128 bytes)

IP ID Support

0x0000 to 0xffff

0x0000 to 0x7fff reserved for segmentation offload

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