Intel PCI User Manual
Receive and Transmit Description
42
Software Developer’s Manual
3.3.6
TCP/IP Context Descriptor Layout
The following section describes the layout of the TCP/IP context transmit descriptor.
To select this descriptor format, bit 29 (TDESC.DEXT) must be set to 1b and TDESC.DTYP must
be set to 0000b. In this case, the descriptor format is defined as shown in
be set to 0000b. In this case, the descriptor format is defined as shown in
Note that the TCP/IP context descriptor does not transfer any packet data. It merely prepares the
checksum hardware for the TCP/IP Data descriptors that follow.
Table 3-13. Transmit Descriptor (TDESC) Layout – (Type = 0000b)
Note: The first quadword of this descriptor type contains parameters used to calculate the two checksums
which may be offloaded.
63
48 47
40 39
32 31
16 15
8 7
0
0
TUCSE
TUCSO
TUCSS
IPCSE
IPCSO
IPCSS
8
MSS
HDRLEN RSV
STA
TUCMD
DTYP
PAYLEN
63
48 47
40 39 36 35 32 31
24 23 20 19
0