82598EB Datasheet, PDF (259/596 Pages) Intel Corporation – Intel® 82598EB 10 Gigabit Ethernet Controller Datasheet

Intel^® 82598EB 10 GbE Controller - Transmit Functionality
• Identification Field should be set as appropriate for first packet of send (if not already)
• Header checksum should be zeroed out unless some adjustment is needed by the driver
TCP Header
• Sequence number should be set as appropriate for first packet of send (if not already)
• PSH, and FIN flags should be set as appropriate for LAST packet of send
• TCP Checksum should be set to the partial pseudo-header checksum as follows (there is a more
detailed discussion of this in Section 3.5.3.4.5:
Table 3-73. TCP Partial Pseudo-Header Checksum for IPv4
Zero
IP Source Address
IP Destination Address
Layer 4
Protocol ID
Zero
Table 3-74. TCP Partial Pseudo-Header Checksum for IPv6
IPv6 Source Address
IPv6 Final Destination Address
Zero
Zero
Next Header
UDP Header
• Checksum should be set as in TCP header previously described.
The 82598's DMA function fetches the Ethernet, IP, and TCP/UDP prototype header information from
the initial descriptor(s) and saves them (on-chip) for individual packet header generation. The following
sections describe the updating process performed by the hardware for each frame sent using the TCP
segmentation capability.
3.5.3.4.5 IP and TCP/UDP Headers
This section outlines the format and content for the IP, TCP, and UDP headers. The 82598 requires
baseline information from the device driver in order to construct the appropriate header information
during the segmentation process. Note that header fields that are modified by the 82598 are
highlighted in the figures that follow.
Note:
IPv4 requires the use of a checksum for the header and does not use a header checksum.
IPv4 length includes the TCP and IP headers, and data. IPv6 length does not include the IPv6
header.
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