Data Sheet

Ethernet Controller I210 —Inline Functions
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Note: The VFE bit does not affect whether the VLAN tag is stripped. It only affects whether the
VLAN packet passes the receive filter.
Table 7-56 lists reception actions per control bit settings.
Note: A packet is defined as a VLAN/802.1Q packet if its type field matches the VET.
7.4.5 Double VLAN Support
The I210 supports a mode where most of the received and sent packet have at least one VLAN tag in
addition to the regular tagging which might optionally be added. This mode is used for systems where
the switches add an additional tag containing switching information.
Note: The only packets that might not have the additional VLAN are local packets that does not
have any VLAN tag.
This mode is activated by setting CTRL_EXT.EXT_VLAN bit. The default value of this bit is set according
to the EXT_VLAN (bit 1) in the Initialization Control 3 Flash word.
The type of the VLAN tag used for the additional VLAN is defined in the VET.VET_EXT field.
7.4.5.1 Transmit Behavior With External VLAN
It is expected that the driver include the external VLAN header as part of the transmit data structure.
Software might post the internal VLAN header as part of the transmit data structure or embedded in the
transmit descriptor (see Section 7.2.2 for details). The I210 does not relate to the external VLAN
header other than the capability of “skipping” it for parsing of inner fields.
Notes:
•If the CTRL_EXT.EXT_VLAN bit is set the VLAN header in a packet that carries a single
VLAN header is treated as the external VLAN.
•If the CTRL_EXT.EXT_VLAN bit is set the I210 expects that any transmitted packet to
have at least the external VLAN added by the software. For those packets where an
external VLAN is not present, any offload that relates to inner fields to the EtherType
might not be provided.
Table 7-56. Packet Reception Decision Table
Is packet
802.1Q?
CTRL.
VME
RCTL.
VFE
Action
No X
1
1. X - Don’t care
X
1
Normal packet reception
Yes 0b 0b
Receive a VLAN packet if it passes the standard MAC address filters (only). Leave the
packet as received in the data buffer. VP bit in receive descriptor is cleared.
Yes 0b 1b
Receive a VLAN packet if it passes the standard filters and the VLAN filter table. Leave
the packet as received in the data buffer (the VLAN tag would not be stripped). VP bit in
receive descriptor is cleared.
Yes 1b 0b
Receive a VLAN packet if it passes the standard filters (only). Strip off the VLAN
information (four bytes) from the incoming packet and store in the descriptor. Sets VP
bit in receive descriptor.
Yes 1b 1b
Receive a VLAN packet if it passes the standard filters and the VLAN filter table. Strip off
the VLAN information (four bytes) from the incoming packet and store in the descriptor.
Sets VP bit in receive descriptor.