Data Sheet

Inline Functions—Ethernet Controller I210
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• Legacy Transmit Descriptors:, The Tag Control Information (TCI) of the 802.1Q tag comes from the
VLAN field (see Figure 7-8) of the descriptor. Refer to Table 7-26, for more information regarding
hardware insertion of tags for transmits.
• Advanced Transmit Descriptor: The Tag Control Information (TCI) of the 802.1Q tag comes from
the VLAN Tag field (see Table 7.2.2.2.1) of the advanced context descriptor. The IDX field of the
advanced Tx descriptor should be set to the adequate context.
7.4.3.2 Stripping 802.1Q Tags on Receives
Software might instruct the I210 to strip 802.1Q VLAN tags from received packets. If VLAN stripping is
enabled and the incoming packet is an 802.1Q VLAN packet (its Ethernet Type field matched the VET),
then the I210 strips the 4 byte VLAN tag from the packet, and stores the TCI in the VLAN Tag field (see
Figure 7-4 and See “Receive UDP Fragmentation Checksum) of the receive descriptor.
The I210 also sets the VP bit in the receive descriptor to indicate that the packet had a VLAN tag that
was stripped. If the CTRL.VME bit is not set, the 802.1Q packets can still be received if they pass the
receive filter, but the VLAN tag is not stripped and the VP bit is not set.
VLAN stripping can be enabled using two different modes:
1. By setting the DVMOLR.STRVLAN for the relevant queue.
2. By setting the CTRL.VME bit.
7.4.4 802.1Q VLAN Packet Filtering
VLAN filtering is enabled by setting the RCTL.VFE bit to 1b. If enabled, hardware compares the type
field of the incoming packet to a 16-bit field in the VLAN Ether Type (VET) register. If the VLAN type
field in the incoming packet matches the VET register, the packet is then compared against the VLAN
Filter Table Array (VFTA[127:0]) for acceptance.
The I210 provides exact VLAN filtering for VLAN tags for host traffic and VLAN tags for manageability
traffic.
7.4.4.1 Host VLAN Filtering:
The Virtual LAN ID field indexes a 4096 bit vector. If the indexed bit in the vector is one; there is a
Virtual LAN match. Software might set the entire bit vector to ones if the node does not implement
802.1Q filtering. The register description of the VLAN Filter Table Array is described in detail in
Section 8.10.18.
In summary, the 4096-bit vector is comprised of 128, 32-bit registers. The VLAN Identifier (VID) field
consists of 12 bits. The upper 7 bits of this field are decoded to determine the 32-bit register in the
VLAN Filter Table Array to address and the lower 5 bits determine which of the 32 bits in the register to
evaluate for matching.
7.4.4.2 Manageability VLAN Filtering:
The MC configures the I210 with eight different manageability VIDs via the Management VLAN TAG
Value [7:0] - MAVTV[7:0] registers and enables each filter in the MDEF register.
Two other bits in the Receive Control register (see Section 8.10.1), CFIEN and CFI, are also used in
conjunction with 802.1Q VLAN filtering operations. CFIEN enables the comparison of the value of the
CFI bit in the 802.1Q packet to the Receive Control register CFI bit as acceptance criteria for the
packet.