DS33X11+ Maxim Integrated Products, DS33X11+ Datasheet - Page 99

• Manufacturer Part Number: DS33X11+
• Description: IC MAPPING ETHERNET 144CSBGA
• Manufacturer: Maxim Integrated Products

Specifications of DS33X11+

• Applications: Data Transport
• Interface: SPI
• Voltage - Supply: 1.8V, 2.5V, 3.3V
• Package / Case: 144-CSBGA
• Mounting Type: Surface Mount
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

8.21 CIR/CBS Controller
The device provides a Committed Information Rate (CIR) / Committed Burst Rate (CBS) provisioning facility. The
CIR/CBS can be used to restrict the transport of received MAC data to a specific rate. The CIR will restrict the data
flow from the Receive MAC to Transmit Packet Processor. Policing parameters are user-defined in the SU.L1PP
and SU.L2PP registers. The data rate increments for CIR/CBS provision that are available to the user are based on
the operational data rate and are approximately: 64kbps from DC to 2Mbps, 2Mbps from 2Mbps to 64Mbps, and
16Mbps from 16Mbps to 416Mbps. The CIR function is based on a time-averaged value of bytes transmitted. When
the CIR is enabled, the average bytes per second of Ethernet traffic forwarded to the serial WAN interfaces is
limited to the configured CIR. The transmit CBS for all CIR settings is selectable using SU.L1PP.CBSS and
SU.L2PP.CBSS.
Some details regarding operation of the CIR are as follows:
The user provides the following configuration parameters:
Parameter
Policing
Operating
Range
CIR Credit
Threshold
Rev: 063008
________________________________________________ DS33X162/X161/X82/X81/X42/X41/X11/W41/W11
•
•
•
The maximum value of CIR cannot effectively exceed the aggregate serial transmit line rate.
If the data rate received from the Ethernet interface is higher than the CIR, the device can be configured to
invoke flow control or to discard frames to reduce the forwarded traffic rate.
CIR function is only available for data received at the Ethernet Interface to be forwarded to WAN. There is
not a CIR function for data arriving from the WAN to be sent to the Ethernet Interface.
Configured settings
Off
Policing Pause Enabled
Policing Discard Enabled
64kbps to 2Mbps
2Mbps to 64Mbps
16Mbps to 416Mbps
8-bit value
Description
Enables/Disables the CIR/CBS Policing function.
Enables Pause flow control when CIR is exceeded.
Enabled Discarding of frames when CIR is exceeded.
Low-Range CIR.
Mid-Range CIR.
High-Range CIR.
This setting allows approximate incremental steps of:
64kbps each LSB, for the 64kbps to 2Mbps operating range
2Mbps each LSB, for the 2Mbps to 64Mbps operating range
16Mbps each LSB, for the 16Mbps to 416Mbps operating range
99 of 375