SMSC LAN91C111 - Manual (Page 66)

10/100 Non-PCI Ethernet Single Chip MAC + PHY
Datasheet
Revision 1.91 (08-18-08) 66 SMSC LAN91C111 REV C
DATASHEET
8.22 Bank 3 - Multicast Table Registers
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.
OFFSET NAME TYPE SYMBOL
0
THROUG
H 7 MULTICAST TABLE READ/WRITE MT
LOW
BYTE
MULTICAST TABLE 0
0 0 0 0 0 0 0 0
HIGH
BYTE
MULTICAST TABLE 1
0 0 0 0 0 0 0 0
LOW
BYTE
MULTICAST TABLE 2
0 0 0 0 0 0 0 0
HIGH
BYTE
MULTICAST TABLE 3
0 0 0 0 0 0 0 0
LOW
BYTE
MULTICAST TABLE 4
0 0 0 0 0 0 0 0
HIGH
BYTE
MULTICAST TABLE 5
0 0 0 0 0 0 0 0
LOW
BYTE
MULTICAST TABLE 6
0 0 0 0 0 0 0 0
HIGH
BYTE
MULTICAST TABLE 7
0 0 0 0 0 0 0 0