82598EB Datasheet, PDF (249/596 Pages) Intel Corporation – Intel® 82598EB 10 Gigabit Ethernet Controller Datasheet

Intel^® 82598EB 10 GbE Controller - Transmit Functionality
Table 3-67. VLAN Field (TDESC.VLAN) Layout
15 13
12
11
0
PRI
CFI
VLAN
3.5.3.3.1.2 Advanced Transmit Context Descriptor
Table 3-68. Transmit Context Descriptor (TDESC) Layout – (Type = 0010b)
63
0
8
63
MSS
48
47
40
39
32 31
16 15
9
RSV
VLAN
MACLEN
L4LEN
IDX
RSV
ADV
DTYP
TUCMD
48 47 40 39 36 35 32 31 24 23 20 19
9
8
0
IPLEN
Reserved
8
0
IPLEN (9)
This field holds the value of the IP header length for the IP checksum off-load feature. If an offload is
requested, IPLEN must be greater than or equal to six, and less than or equal to 511.
MACLEN (7)
This field indicates the length of the MAC header. When an offload is requested (TSE or IXSM or TXSM is
set), MACHDR must be larger than or equal to 14, and less than or equal to 127.
VLAN (16)
This field contains the 802.1Q VLAN tag to be inserted in the packet during transmission. This VLAN tag
is inserted when a packet using this context has its DCMD.VLE bit is set.
TUCMD (11)
• RSV (bit 10-5) – Reserved
• RSV (bit 4) – Reserved
• L4T (bit 3:2) – L4 packet type (00b: UDP; 01b: TCP; 10b, 11b: RSV)
• IPV4(bit 1) – IP packet type: When 1b, IPv4; when 0b, IPv6
• SNAP (bit 0) – SNAP indication
DTYP (4)
This field is always 0010b for this type of descriptor.
ADV (8)
• Reserved (bits 7:6) – Reserved
• DEXT (bit 5) – Descriptor extension (1b for advanced mode)
• Reserved (bits 4:0) – Reserved
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