Task Offload (NDIS 5.1)

Note   NDIS 5. x has been deprecated and is superseded by NDIS 6. x. For new NDIS driver development, see Network Drivers Starting with Windows Vista. For information about porting NDIS 5. x drivers to NDIS 6. x, see Porting NDIS 5.x Drivers to NDIS 6.0.

To increase its performance, the Microsoft TCP/IP transport can offload one or more of the following tasks to a NIC that has the appropriate task-offload capabilities:
  • Checksum tasks.

    The TCP/IP transport can offload the calculation and/or validation of IP and/or TCP checksums.

  • Internet Protocol Security tasks

    The TCP/IP transport can offload the calculation and validation of encrypted checksums for authentication headers (AH) and/or encapsulating security payloads (ESP). The TCP/IP transport can also offload the encryption and decryption of ESP payloads. In addition, the transport can offload the encryption and decryption of UDP-encapsulated ESP data packets.

  • Segmentation of large TCP packets

    The TCP/IP transport supports Large Send Offload (LSO). With LSO, the TCP/IP transport can offload the segmentation of large TCP packets.

The TCP/IP transport supports task offload only for IPv4 packets.

Offloading tasks from the TCP/IP transport to a NIC involves two major operations:

 

 

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