CN8236EBGB Mindspeed Technologies, CN8236EBGB Datasheet - Page 198

• 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

6.0 Traffic Management
6.3 ABR Flow Control Manager
6-30
Table 6-5. ABR Cell Type Decision Vector (ACDV)
an in-rate Forward RM cell is transmitted, FWD_INDEX is copied to
CELL_INDEX; otherwise, CELL_INDEX is incremented by one
(CELL_INDEX++). Therefore, the number of blocks in a Decision table is
bounded by the maximum number of cell decisions made between transmitted
Forward RM cells, typically Nrm.
APPLICATION EXAMPLE: Cell Decision Table for Nrm = 32
table, the FWD_INDEX ACDB, is located at index 100 of the ABR
Decision table. Whenever a Forward RM cell is sent, this ARCB serves as
the reset point for the decision state machine. When
CELL_INDEX = FWD_INDEX, a steady state ABR channel transmits a
Backward RM cell and advances the CELL_INDEX. The diagram shows
the next ACDB (101) in more detail. It contains the 16 Cell Type Actions
(For example, BRM = Send Backward RM). At the next cell transmission
opportunity, the ABR Flow Control Manager state machine selects a cell
type by indexing into the ACDB according to the ACDV. In this case, the
only condition present is RUN = 1, so ACDV = 0001b. Cell Type Action
Index 1 is selected. For this ACDB, Cell Type Action 1 is DATA or Send
Data Cell. Therefore, the CN8236 transmits a user data cell.
131. This ACDB transmits a Forward RM Cell under all circumstances.
Therefore, the CN8236 resets the CELL_INDEX for this VCC to
FWD_INDEX = 100, when it reaches this ACDB.
CN8236 would transmit a Forward RM cell, and the sequence would
continue from the FWD_INDEX.
3
2
1
0
Bit
The SAR updates the CELL_INDEX field after each cell decision is made. If
Figure 6-17
In steady state, CELL_INDEX is incremented until it reaches ACDB
In this example, the host should initialize CELL_INDEX to 131. The
TRM_EXP
TA_PND
TA_XMIT
RUN
Mindspeed Technologies
Name
shows a typical Cell Decision table. The anchor of the
Time since last forward RM transmitted >= TRM
TA_PND bit set in VCC table entry
TA_XMIT bit set in VCC table entry
RUN bit set in VCC table entry
ATM ServiceSAR Plus with xBR Traffic Management
™
Description
28236-DSH-001-B
CN8236