LAN9312 datasheet(276/458 Pages) SMSC

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High Performance Two Port 10/100 Managed Ethernet Switch with 32-Bit Non-PCI CPU Interface

Datasheet

Revision 1.2 (04-08-08)

276

SMSC LAN9312

DATASHEET

14.3.4

Host MAC Multicast Hash Table High Register (HMAC_HASHH)

The 64-bit Multicast table is used for group address filtering. For hash filtering, the contents of the

destination address in the incoming frame is used to index the contents of the Hash table. The most

significant bit determines the register to be used (Hi/Low), while the other five bits determine the bit

within the register. A value of 00000 selects Bit 0 of the Multicast Hash Table Lo register and a value

of 11111 selects the Bit 31 of the Multicast Hash Table Hi register.

If the corresponding bit is 1, then the multicast frame is accepted. Otherwise, it is rejected. If the “Pass All

Multicast” (MCPAS) bit of the Host MAC Control Register (HMAC_CR) is set, then all multicast frames are

accepted regardless of the multicast hash values.

The Multicast Hash Table High register contains the higher 32 bits of the hash table and the Multicast

Hash Table Low register contains the lower 32 bits of the hash table. Refer to Section 9.4, "Address

Filtering," on page 114 for more information on address filtering.

This table determines if the Host MAC accepts the packets from the switch fabric. The switch fabric

address table and configuration determine the packets that get sent to the Host MAC.

Offset:

Size:

32 bits

BITS

DESCRIPTION

TYPE

DEFAULT

31:0

Upper 32-bits of the 64-bit Hash Table

R/W

00000000h

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