LAN9420 Datasheet, PDF (62/171 Pages) SMSC Corporation – Single-Chip Ethernet Controller with HP Auto-MDIX Support and PCI Interface

Single-Chip Ethernet Controller with HP Auto-MDIX Support and PCI Interface
Datasheet
{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
Calculate Checksum
Figure 3.22 Ethernet Frame with Length Field and SNAP Header
{DSAP, SSAP, CTRL,
OUI[23:16]}
{OUI[15:0], PID[15:0]}
DST
SRC
8
1
0
0
VL
Ie
Dn
S
N
A
P
0
S
N
A
P
1
L3 Packet
F
C
S
0123456
Calculate Checksum
Figure 3.23 Ethernet Frame with VLAN Tag and SNAP Header
{DSAP, SSAP, CTRL,
OUI[23:16]}
{OUI[15:0], PID[15:0]}
DST
SRC
8
1
0
0
V
I
D
8
1
0
0
VL
Ie
Dn
S
N
A
P
0
S
N
A
P
1
L3 Packet
F
C
S
01245678
Calculate Checksum
Figure 3.24 Ethernet Frame with multiple VLAN Tags and SNAP Header
The RXCOE supports a maximum of two VLAN tags. If there are more than two VLAN tags, the VLAN
protocol identifier for the third tag is treated as an Ethernet type field. The checksum calculation will
begin immediately after the type field.
Revision 1.6 (07-18-11)
62
DATASHEET
SMSC LAN9420/LAN9420i