SMSC LAN9420 - Manual (Page 130)

Single-Chip Ethernet Controller with HP Auto-MDIX Support and PCI Interface
Datasheet
Revision 1.22 (09-25-08) 130 SMSC LAN9420/LAN9420i
DATASHEET
4.4.9 VLAN1 Tag Register (VLAN1)
This register contains the VLAN tag field to identify VLAN1 frames. For VLAN frames the legal frame
length is increased from 1518 bytes to 1522 bytes.
The RXCOE also uses this register to determine the protocol value to use to indicate the existence of
a VLAN tag. When using the RXCOE, this value may only be changed if the RX path is disabled. If it
is desired to change this value during run time, it is safe to do so only after the MAC is disabled and
the MIL is empty.
Offset: 00A0h Size: 32 bits
BITS DESCRIPTION TYPE DEFAULT
31:16 RESERVED RO -
15:0 VLAN1 Tag Identifier (VTI1)
This contains the VLAN Tag field to identify the VLAN1 frames. This field is
compared with the 13
th and 14 th bytes of the incoming frames for VLAN1
frame detection.
R/W FFFFh