Task Offload
To increase its performance, the Microsoft TCP/IP transport can offload tasks to a NIC that has the appropriate task offload capabilities.
Windows Vista supports the following task offload services:
Checksum tasks
The TCP/IP transport can offload the calculation and validation of IP and TCP checksums.
Internet protocol security offload version 1 (IPsecOV1)
The TCP/IP transport can offload the calculation and validation of encrypted checksums for authentication headers (AH), encapsulating security payloads (ESP), or both. The TCP/IP transport can also offload the encryption and decryption of ESP payloads and the encryption and decryption of user datagram protocol (UDP)-encapsulated ESP data packets.
Internet protocol security offload version 2 (IPsecOV2)
The TCP/IP transport can offload the calculation and validation of encrypted checksums for authentication headers (AH), encapsulating security payloads (ESP), or both. The TCP/IP transport can also offload the encryption and decryption of ESP payloads and the encryption and decryption of user datagram protocol (UDP)-encapsulated ESP data packets. IPsecOV2 is supported in NDIS 6.1 and later versions.
Large send offload version 1 (LSOV1)
The TCP/IP transport supports large send offload version 1 (LSOV1). With LSOV1, the TCP/IP transport can offload the segmentation of large (up to 64 KB including the IP header) TCP packets for IPv4.
Large send offload version 2 (LSOV2)
The large send offload version 2 (LSOV2) interface is an enhanced version of LSOV1. LSOV2 supports IPv6, IPv4, and segmentation for large TCP packets that are larger than 64K. For more information about offloading the segmentation of large packets, see Offloading the Segmentation of Large TCP Packets.