26 C HAPTER 1: I NTRODUCTIONWindows 2000 Offload FeaturesAdditionally, the 3CR990 NIC supports Windows 2000offload features in an IP environment. The Windows 2000offload features are designed to enhance theWindows 2000 operating system capabilities by off loadingkey TCP/IP networking and security tasks from theWindows 2000 operating system: IPSec Offload—reduces CPU utilization by allowing the3XP processor and a crypto chip on the NIC to performdata encryption operations. TCP Segmentation Offload—reduces CPU utilization byallowing the 3XP processor on the NIC to performsegmentation of TCP packets. IP and TCP Checksum Offload—reduced CPU utilizationby allowing the 3XP processor on the NIC to performthe checksum calculation of TCP/IP and UDP/IP packets. 802.1P Packet Priority Offload—reduces CPU utilizationby allowing the 3XP processor on the NIC to performthe insertion of the 802.1Q tag header into the packet.For more information on enabling and disabling offloadsfor Windows 2000, see Using Windows 2000 OffloadFeatures on page 73.Windows 2000 does not allow IPSec offloads and TCPSegmentation offloads for the same session. Though alloffload types may be enabled, TCP Segmentationoffloading will not occur during an IPSec session.
