82596DX Datasheet, PDF (43/77 Pages) Intel Corporation – HIGH-PERFORMANCE 32-BIT LOCAL AREA NETWORK COPROCESSOR

82596DX SX
MULTICAST-SETUP
This command is used to load the 82596 with the Multicast-IDs that should be accepted As noted previously
the filtering done on the Multicast-IDs is not perfect and some unwanted frames may be accepted This
command resets the current filter and reloads it with the specified Multicast-IDs The format of the Multicast-
addresses setup command is
31
ODD WORD
16 15
EVEN WORD
0
EL S I X X X X X X X X X X 0 1 1 C B OK A 0 0 0 0 0 0 0 0 0 0 0 0
XX
MC COUNT
A15
LINK OFFSET
A0
4th byte
1st byte
MULTICAST ADDRESSES LIST
Nth byte
Figure 26 MC Setup 82586 and 32-Bit Segmented Modes
31
ODD WORD
16 15
EVEN WORD
0
EL S I 0 0 0 0 0 0 0 0 0 0 0 1 1 C B OK A 0 0 0 0 0 0 0 0 0 0 0 0
A31
LINK ADDRESS
A0
2nd byte
1st byte X X
MC COUNT
MULTICAST ADDRESSES LIST
Nth byte
Figure 27 MC Setup Linear Mode
where
LINK ADDRESS
EL B C I S
A
Bits 19–28
CMD (bits 16–18)
MC-CNT
MC LIST
As per standard Command Block (see the NOP command for details)
Indicates that the command was abnormally terminated due to a CU Abort control
command If one then the command was aborted and if necessary it should be
repeated If this bit is zero the command was not aborted
Reserved (0 in both the 32-Bit Segmented and Linear Modes)
The MC SETUP command value 3h
This 14-bit field indicates the number of bytes in the MC LIST field The MC CNT
must be a multiple of the ADDR LEN otherwise the 82596 reduces the MC CNT to
the nearest ADDR LEN multiple MC CNT^e0 implies resetting the Hash table
which is equivalent to disabling the Multicast filtering mechanism
A list of Multicast Addresses to be accepted by the 82596 The least significant bit
of each MC address must be 1
NOTE
The list is sequential i e the most significant byte of an address is immediately followed by the least signifi-
cant byte of the next address
When the 82596 is configured to recognize multiple Individual Address (Multi-IA)
the MC-Setup command is also used to set up the Hash table for the individual
address
The least significant bit in the first byte of each IA address must be 0
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