RTL8169
2002/03/27 Rev.1.21
52
4 17 TAGC
VLAN tag control bit: 1: Enable; 0: Disable.
1: Add TAG. 0x8100 (Ethernet encoded tag protocol ID, indicating
that this is a IEEE 802.1Q VLAN packet) is inserted after source
address, and 2 bytes are inserted after tag protocol ID from
VLAN_TAG field in transmit descriptor.
0: Packet remains unchanged when transmitting. I.e., the packet
transmitted is the same as it was passed down by upper layer.
4 16 RSVD
Reserved
4 15:0 VLAN_TAG The 2-byte VLAN_TAG contains information, from the upper layer, o
user priority, canonical format indication, and VLAN ID. Please refer to
IEEE 802.1Q for more VLAN tag information.
VIDH: The high 4 bits of a 12-bit VLAN ID.
VIDL: The low 8 bits of a 12-bit VLAN ID.
PRIO: 3-bit 8-level priority.
CFI: Canonical Format Indicator.
8 31:0 TxBuffL
Low 32-bit address of transmit buffer
12 31:0 TxBuffH
High 32-bit address of transmit buffer
Normal (including IP, TCP, UDP Checksum Task Offloads) Tx Descriptor Format (before transmitting, OWN=1,
LGSEN=0, Tx command mode 1)
bit
31 30 29 28 27 26 16 15 8 7 6 5 4 3 2 1 0
O
W
N
=
1
F
S
L
S
L
G
S
E
N
=
0
R
S
V
D
R
S
V
D
R
S
V
D
R
S
V
D
R
S
V
D
R
S
V
D
R
S
V
D
R
S
V
D
I
P
C
S
U
D
P
C
S
T
C
P
C
S
Frame_Length
Offset 0
VLAN_TAG
RSVD
T
A
G
C
R
S
V
D
VIDL PRIO C
FI
VIDH
Offset 4
TX_BUFFER_ADDRESS_LOW
Offset 8
TX_BUFFER_ADDRESS_HIGH
Offset 12
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