LAN9730 Datasheet, PDF (70/222 Pages) SMSC Corporation – High-Speed Inter-Chip (HSIC) USB 2.0

LAN9730/LAN9730i
In mode 1, the RXCOE supports VLAN tags and a SNAP header. In this mode, the RXCOE calculates the checksum at
the start of L3 packet. The VLAN1 tag register is used by the RXCOE to indicate what protocol type is to be used to
indicate the existence of a VLAN tag. This value is typically 8100h.
Example frame configurations:
FIGURE 4-11:
TYPE II ETHERNET FRAME
p
DST
SRC
r
o
t
L3 Packet
F
C
S
0123
1DWORD
Calculate Checksum
FIGURE 4-12:
ETHERNET FRAME WITH VLAN TAG
DST
SRC
8
1
0
0
V
I
D
t
y
p
e
L3 Packet
F
C
S
01234
1DWORD
Calculate Checksum
FIGURE 4-13:
ETHERNET FRAME WITH LENGTH FIELD AND SNAP HEADER
{DSAP, SSAP, CTRL, OUI[23:16]}
{OUI[15:0], PID[15:0]}
SS
LN N
F
DST SRC e A A
L3 Packet
C
nP P
S
01
012345
1DWORD
Calculate Checksum
DS00001946A-page 70
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