lan91c100fd Standard Microsystems Corp., lan91c100fd Datasheet - Page 34

• Manufacturer Part Number: lan91c100fd
• Description: Lan91c100fd Rev. B Feast Fast Ethernet Controller With Full Duplex Capability
• Manufacturer: Standard Microsystems Corp.

BANK3
The 64 bit multicast table is used for group address filtering. The hash value is defined as the six most significant bits of the
CRC of the destination addresses. The three msb's determine the register to be used (MT0-MT7), while the other three
determine the bit within the register.
If the appropriate bit in the table is set, the packet is received.
If the ALMUL bit in the RCR register is set, all multicast addresses are received regardless of the multicast table values.
Hashing is only a partial group addressing filtering scheme, but being the hash value available as part of the receive status
word, the receive routine can reduce the search time significantly. With the proper memory structure, the search is limited
to comparing only the multicast addresses that have the actual hash value in question.
SMSC DS – LAN91C100FD REV. B
0 THROUGH 7
BYTE
HIGH
BYTE
BYTE
HIGH
BYTE
BYTE
HIGH
BYTE
BYTE
HIGH
BYTE
OFFSET
LOW
LOW
LOW
LOW
0
0
0
0
0
0
0
0
MULTICAST TABLE
0
0
0
0
0
0
0
0
NAME
0
0
0
0
0
0
0
0
Page 34
MULTICAST TABLE 0
MULTICAST TABLE 1
MULTICAST TABLE 2
MULTICAST TABLE 3
MULTICAST TABLE 4
MULTICAST TABLE 5
MULTICAST TABLE 6
MULTICAST TABLE 7
0
0
0
0
0
0
0
0
READ/WRITE
0
0
0
0
0
0
0
0
TYPE
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
SYMBOL
MT
0
0
0
0
0
0
0
0
Rev. 03-28-07