10/100 Non-PCI Ethernet Single Chip MAC + PHY
Datasheet
8.22
Bank 3 - Multicast Table Registers
OFFSET
NAME
TYPE
SYMBOL
MT
0
THROUG
H 7
MULTICAST TABLE
READ/WRITE
LOW
MULTICAST TABLE 0
BYTE
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
HIGH
BYTE
MULTICAST TABLE 1
0
0
LOW
MULTICAST TABLE 2
BYTE
0
0
HIGH
BYTE
MULTICAST TABLE 3
0
0
LOW
MULTICAST TABLE 4
BYTE
0
0
HIGH
BYTE
MULTICAST TABLE 5
0
0
LOW
MULTICAST TABLE 6
BYTE
0
0
HIGH
BYTE
MULTICAST TABLE 7
0
0
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.
Revision 1.8 (07-13-05)
SMSC LAN91C111-REV B
DATA7S6HEET
SMSC [ SMSC CORPORATION ]
