cn8237 Mindspeed Technologies, cn8237 Datasheet - Page 181

• Manufacturer Part Number: cn8237
• Description: Atm Oc-12 Servicesar Plus With Xbr Traffic Management
• Manufacturer: Mindspeed Technologies

CN8237
ATM OC-12 ServiceSAR Plus with xBR Traffic Management
Figure 6-13. CN8237 ABR-ER Feedback Loop (Source Behavior)
28237-DSH-001-C
6.3.2.1 Source Flow
RSM/SEG
Segmentation
Reassembly
Queue
Control Feedback
Templates
Decision
ABR
Figure 6-13
The CN8237 injects an in-rate cell stream (CLP = 0) into the ATM network for
each ABR VCC. Network elements modify the flow control fields in the cell
stream’s Forward RM cells. After a round trip through the network and
destination node, these cells return to the CN8237 receive port as Backward RM
cells. The reassembly coprocessor processes incoming Backward RM cells, and
communicates with the segmentation state machines via the RSM/SEG Queue in
SAR SEG-shared memory. Upon receiving this feedback from the queue, the
ABR Flow Control Manager updates fields within the SCH_STATE portion of
the segmentation VCC table entry. The xBR Cell Scheduler and segmentation
coprocessor use these fields to generate the ABR in-rate cell stream, closing the
Source Behavior feedback loop.
bit in the data cell header(s) per the rules in TM 4.1.
Flow Control
CN8237 Subsystem
Manager
The SAR also processes the Explicit Forward Congestion Indication (EFCI)
ABR
Mindspeed Technologies
SCH_STATE
Table Entry
SEG VCC
illustrates the feedback loop which controls the Source cell stream.
Decision
Rate
Scheduler
SAR
Cell
Schedule
Table
Segmentation
RSM VCC
Coprocessor
Coprocessor
Reassembly
Table
Entry
Cell Type
Decision
™
BACKWARD_RM
Cell Stream
ABR
UNI
6.3 ABR Flow Control Manager
6.0 Traffic Management
Destination
Network +
ATM
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