CN8237EBGB Mindspeed Technologies, CN8237EBGB Datasheet - Page 182

• Manufacturer Part Number: CN8237EBGB
• Description: ATM SAR 622Mbps 3.3V ABR/CBR/GFR/UBR/VBR 456-Pin BGA
• Manufacturer: Mindspeed Technologies

Specifications of CN8237EBGB

• Package: 456BGA
• Traffic Class: ABR|CBR|GFR|UBR|VBR
• Utopia Type: Level 1|Level 2
• Host Interface: PCI
• Maximum Data Rate: 622 Mbps
• Typical Operating Supply Voltage: 3.3 V
• Minimum Operating Supply Voltage: 3.135 V

6.0 Traffic Management
6.3 ABR Flow Control Manager
Figure 6-14. CN8237 ABR-ER Feedback Generation (Destination Behavior)
6-26
6.3.2.3 Out-of-Rate
6.3.2.2 Destination
FORWARD_RM
BACKWARD_RM
Behavior
Cells
The CN8237 also responds to an incoming ABR cell stream as an ABR
Destination. The reassembly coprocessor processes received Forward RM cells. It
turns around this incoming information to the segmentation coprocessor via the
SCH_STATE part of the segmentation VCC table entry. The segmentation
coprocessor then formats Backward RM cells containing this information and
inserts these turnaround RM cells into the transmit cell stream.
backpressure to the Source. The host notifies the CN8237 of internal system
congestion. The CN8237 passes this information to the Source using Backward
RM cells, to flow control the transmitting Source. The SAR also processes the
EFCI bit in the data cell header(s) per the rules in TM 4.1.
In addition to in-rate cell streams, the CN8237 can also generate out-of-rate
(CLP = 1) cell streams. These CLP = 1 streams compliment and enhance the
information flow contained in the in-rate cell streams. An example of the use of
this mechanism is to send out-of-rate Forward RM cells on a channel if the
transmit rate on that channel has dropped below the schedule table minimum rate.
This provides a mechanism to restart scheduling of an ABR VCC whose rate has
dropped to 0 or below the schedule table minimum rate.
The CN8237 also provides a mechanism for the Destination host to apply
This process is illustrated in
Mindspeed Technologies
Segmentation
Coprocessor
Reassembly
Coprocessor
(Backward RM Cell Formatting)
(Forward RM Cell Processing)
ATM OC-12 ServiceSAR Plus with xBR Traffic Management
Turnaround
Information
Figure
SCH_STATE
Table Entry
Seg VCC
6-14.
™
Backpressure
Congestion
28237-DSH-001-C
Host
CN8237
8237_069