CN8237EBGB Mindspeed Technologies, CN8237EBGB Datasheet - Page 190

• 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 6-19. RR RATE_INDEX Candidate Selection
6-34
RR
ACR – (ACR x RDF)
ACR – (ACR x RDF)
ACR
responses to the relative rate elements in backward RM cells. The CN8237 uses
the CI/NI bits to choose an ARDB candidate from one of these four vectors. For
instance, if CI is set, the VCC must reduce its ACR by (ACR x RDF). The vectors
in the ARDB that are chosen when CI is set point to ARDBs whose
corresponding rates are less than [ACR – (ACR x RDF)]. The CN8237
recognizes the ARDB indicated by the chosen vector, as the RR rate index
candidate.
Backward RM cell into rate index space. This mapping converts the floating point
ER field rate representation to an absolute rate index. This mapping does not
depend on the current rate of the connection. The CN8237 maps ER field to rate
indexes with a programmable piece-wise linear function. Each piece-wise linear
segment is described in the ABR Exponent table. Again, the system designer
pre-calculates this mapping function to eliminate real-time floating point math.
Each ARDB contains vectors to eight other ARDBs. Four of these vectors are
Figure 6-19
The CN8237 calculates the ER candidate by mapping the ER field from the
Mindspeed Technologies
illustrates the RR Rate_INDEX candidate selection.
CANDIDATE
INDEX
RR
ATM OC-12 ServiceSAR Plus with xBR Traffic Management
CONNECTION STATE (RATE_INDEX)
™
(COMPLIANT
RELATIVE
RATES)
ACR x RDF
28237-DSH-001-C
CN8237
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