LAN9220 datasheet(17/142 Pages) MICROCHIP

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DS00002417A-page 17

LAN9220

3.3

Address Filtering Functional Description

The Ethernet address fields of an Ethernet Packet, consists of two 6-byte fields: one for the destination address and

one for the source address. The first bit of the destination address signifies whether it is a physical address or a multicast

address.

The LAN9220 address check logic filters the frame based on the Ethernet receive filter mode that has been enabled.

Filter modes are specified based on the state of the control bits in Table 3-1, "Address Filtering Modes", which shows

the various filtering modes used by the Ethernet MAC Function. These bits are defined in more detail in the “MAC Con-

trol Register”. Please refer to Section 5.4.1, "MAC_CR—MAC Control Register" for more information on this register.

If the frame fails the filter, the Ethernet MAC function does not receive the packet. The host has the option of accepting

or ignoring the packet.

FIGURE 3-1:

VLAN FRAME

TABLE 3-1:

ADDRESS FILTERING MODES

MCPAS

PRMS

INVFILT

HPFILT

Description

MAC address perfect filtering only

for all addresses.

MAC address perfect filtering for

physical address and hash filtering

for multicast addresses

Hash Filtering for physical and

multicast addresses

Inverse Filtering

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