RS8234EBGC Mindspeed Technologies, RS8234EBGC Datasheet - Page 191

• Manufacturer Part Number: RS8234EBGC
• Description: RS8234EBGC ATM XBR SAR
• Manufacturer: Mindspeed Technologies

RS8234
ATM ServiceSAR Plus with xBR Traffic Management
Figure 6-19. Relative Rate (RR) RATE_INDEX Candidate Selection
28234-DSH-001-B
RR
£
ACR - (ACR*RDF)
ACR-(ACR*RDF)
ACR
responses to the relative rate elements in Backward RM cells. The RS8234 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*RDF. The vectors in
the ARDB that is chosen when CI is set point to ARDBs whose corresponding
rates are less than ACR-(ACR*RDF). The RS8234 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. Note that this mapping does
not depend on the current rate of the connection. The RS8234 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
The RS8234 calculates the ER candidate by mapping the ER field from the
Mindspeed Technologies
CANDIDATE
INDEX
RR
CONNECTION STATE (RATE_INDEX)
™
(COMPLIANT
RELATIVE
RATES)
6.3 ABR Flow Control Manager
6.0 Traffic Management
ACR*RDF
100074_058
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