CN8236EBGB Mindspeed Technologies, CN8236EBGB Datasheet - Page 197

• Manufacturer Part Number: CN8236EBGB
• Description: ATM SAR 155Mbps 3.3V ABR/CBR/GFR/UBR/VBR 388-Pin BGA
• Manufacturer: Mindspeed Technologies

Specifications of CN8236EBGB

• Package: 388BGA
• Traffic Class: ABR|CBR|GFR|UBR|VBR
• Utopia Type: Level 1|Level 2
• Host Interface: PCI
• Maximum Data Rate: 155 Mbps
• Typical Operating Supply Voltage: 3.3 V
• Minimum Operating Supply Voltage: 3 V

CN8236
ATM ServiceSAR Plus with xBR Traffic Management
Figure 6-16. Cell Type Interleaving on ABR-ER Cell Stream
28236-DSH-001-B
6.3.6.2 ABR Cell
Decisions
(SCH_STATE)
State Table
SEG VCC
user can modify it to optimize performance or react to changes in the ABR
specification. Furthermore, multiple tables allow groups of VCCs to be tuned for
different network policies.
The Cell Decision Tables reside in SAR-shared memory as a segment of the Flow
Control Manager’s ABR Instruction table. Each entry of a table is an ABR Cell
Decision Block (ACDB). Each ACDB contains sixteen Cell Type Actions. Cell
Type Actions result in one of four decisions: send in-rate Forward RM cell, send
in-rate Backward RM cell, send user data cell, or no action. A Cell Type Action is
chosen by a 4-bit ABR Cell Type Decision Vector (ACDV). The four bits of the
ACDV correspond to four current ABR VCC conditions.
Initialization Instructions
At system initialization, the host loads one of more Cell Decision Tables into
SAR-shared memory. Mindspeed provides standard Cell Decision Tables. The
system designer uses either these or customized templates.
at connection setup time. The first field, CELL_INDEX, tracks the current
ACDB position of the VCC. Source Behavior #2 specifies that the first in-rate
cell on a VCC is a Forward RM cell. Therefore, CELL_INDEX should be
initialized to an ACDB position which always decides to send a Forward RM cell.
The second field, FWD_INDEX, provides a reset point for the in-rate cell stream
sequence. Whenever the CN8236 transmits an in-rate Forward RM cell, it copies
FWD_INDEX to CELL_INDEX.
Run-time Operation
Each time an ABR cell-transmit opportunity arises, the CN8236 makes a cell
decision. The SAR retrieves CELL_INDEX from SCH_STATE and chooses a
Cell Type Action location within the current ACDB.
conditions that are used to form this vector. The presence of a condition sets the
vector bit to a 1.
Since the Cell Decision table template resides in SAR-shared memory, the
To assign an ABR VCC to a table, the host initializes two SCH_STATE fields
Data Cell
Forward RM
Backward RM
None
Mindspeed Technologies
Manager
Control
Flow
ABR
Cell Type
Action
Decision
Table
Cell
™
ABR-ER Cell Stream
Table 6-5
6.3 ABR Flow Control Manager
6.0 Traffic Management
shows the four
8236_048
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