SMSC LAN9312 - Manual (Page 395)

High Performance Two Port 10/100 Managed Ethernet Switch with 32-Bit Non-PCI CPU Interface
Datasheet
SMSC LAN9312 395 Revision 1.4 (08-19-08)
DATASHEET
14.5.3.26.1 INGRESS RATE TABLE REGISTERS
The ingress rate metering/color table consists of 24 Committed Information Rate (CIR) registers (one
per port/priority), a Committed Burst Size register, and an Excess Burst Size register. All metering/color
table registers are 16-bits in size and are accessed indirectly via the
Switch Engine Ingress Rate
Command Register (SWE_INGRSS_RATE_CMD) . Descriptions of these registers are detailed in
Table 14.13 below.
Table 14.13 Metering/Color Table Register Descriptions
DESCRIPTION TYPE DEFAULT
Excess Burst Size
This register specifies the maximum excess burst size in bytes. Bursts larger than
this value that exceed the excess data rate are dropped.
Note: Either this value or the Committed Burst Size should be set larger than or
equal to the largest possible packet expected.
Note: All of the Excess Burst token buckets are initialized to this default value.
If a lower value is programmed into this register, the token buckets will
need to be normally depleted below this value before this value has any
affect on limiting the token bucket maximum values.
This register is 16-bits wide.
R/W 0600h
Committed Burst Size
This register specifies the maximum committed burst size in bytes. Bursts larger
than this value that exceed the committed data rate are subjected to random
dropping.
Note: Either this value or the Excess Burst Size should be set larger than or
equal to the largest possible packet expected.
Note: All of the Committed Burst token buckets are initialized to this default
value. If a lower value is programmed into this register, the token buckets
will need to be normally depleted below this value before this value has
any affect on limiting the token bucket maximum values.
This register is 16-bits wide.
R/W 0600h
Committed Information Rate (CIR)
These registers specify the committed data rate for the port/priority pair. The rate
is specified in time per byte. The time is this value plus 1 times 20nS.
There are 24 of these registers each 16-bits wide.
R/W 0014h