High Performance Two Port 10/100 Managed Ethernet Switch with 32-Bit Non-PCI CPU Interface
Datasheet
14.5.4.10
Buffer Manager Random Discard Table Command Register (BM_RNDM_DSCRD_TBL_CMD)
Register #:
1C09h
Size:
32 bits
This register is used to read and write the Random Discard Weight table. A write to this address
performs the specified access. This table is used to set the packet drop probability verses the buffer
usage.
For a read access, the Buffer Manager Random Discard Table Read Data Register
(BM_RNDM_DSCRD_TBL_RDATA) can be read following a write to this register.
For a write access, the Buffer Manager Random Discard Table Write Data Register
(BM_RNDM_DSCRD_TBL_WDATA) should be written before writing this register.
BITS
DESCRIPTION
TYPE
DEFAULT
31:5
4
RESERVED
RO
-
Random Discard Weight Table RnW
Specifies a read (1) or a write (0) command.
R/W
0b
3:0
Random Discard Weight Table Index
Specifies the buffer usage range that is accessed.
R/W
0h
There are a total of 16 probability entries. Each entry corresponds to a range
of the number of buffers used by the ingress port. The ranges are structured
to give more resolution towards the lower buffer usage end.
BIT
VALUES
BUFFER USAGE LEVEL
0000
0001
0010
0011
0100
0101
0110
0111
1000
1001
1010
1011
1100
1101
1110
1111
0 to 7
8 to 15
16 to 23
24 to 31
32 to 39
40 to 47
48 to 55
56 to 63
64 to 79
80 to 95
96 to 111
112 to 127
128 to 159
160 to 191
192 to 223
224 to 255
SMSC LAN9312
421
Revision 1.2 (04-08-08)
DATASHEET
SMSC [ SMSC CORPORATION ]
