EP80579 Datasheet, PDF (1384/1916 Pages) Intel Corporation – Intel® EP80579 Integrated Processor Product Line

Intel^® EP80579 Integrated Processor
— 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 “IP and TCP/UDP Headers” just
before Figure 37-40:
Figure 37-33.TCP Partial Pseudo-Header Checksum for IPv4
0
Zero
31
IP Source Address
IP Destination Address
Protocol ID
Zero
Figure 37-34.TCP Partial Pseudo-Header Checksum for IPv6
0
31
IP Source Address
IP Destination Address
Zero
Zero
Next Header
• UDP Header
— Checksum should be set as in TCP header, shown in Figure 37-33 and
Figure 37-34.
The GbE DMA function will fetch the Ethernet, IP, and TCP/UDP prototype header
information from the initial descriptor(s) and save them in hardware 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.
37.5.7.6.2 TCP Segmentation Use of Multiple Data Descriptors
TCP Segmentation allows the packet to be segmented to be describe more than one
data descriptor. A large packet contained in a single virtual-address buffer may be more
simply described by a series of data descriptors, each referencing a single physical
address page.
There is only one requirement for multiple data descriptors for TCP segmentation:
• If multiple data descriptors are used to describe the IP/TCP/UDP header section,
each descriptor must describe one or more complete headers; descriptors
referencing only parts of headers are not supported.
Note:
It is recommended that the entire header section, as described by the TCP Context
Descriptor HDRLEN field, be coalesced into a single buffer and described using a single
data descriptor.
37.5.7.7
IP and TCP/UDP Headers
This section outlines the format and content for the IP, TCP and UDP headers. The GbE
requires baseline information from the device driver in order to construct the
appropriate header information during the segmentation process.
Header fields that are modified by the GbE are highlighted in the figures below.
Intel^® EP80579 Integrated Processor Product Line Datasheet
1384
August 2009
Order Number: 320066-003US