pxf4336 Infineon Technologies Corporation, pxf4336 Datasheet - Page 108

• Manufacturer Part Number: pxf4336
• Description: Abm Premium Atm Buf Fer Manager
• Manufacturer: Infineon Technologies Corporation

3.5.1.9
The VS/VD behavior is very similar to the terminal source and destination behavior.
VS/VD source behavior performs two different tasks:
• Calculation of the ACR and appropriate adjustment of the sending rate.
• Multiplexing of user cells, FRM cells and BRM cells.
Calculation of ACR is done by using the CI/NI and ER conveyed in the BRM cells and
taking into consideration some further constraints:
• ACR must stay between MCR and PCR.
• In the absence of received BRM cells the source assumes heavy congestion in the
• After time-outs, the ACR is reduced to ICR.
In the ABM-P, the ACR is programmed to the peak rate limiter of a queue. Then the rule
is fulfilled that the actual sending rate shall never be higher than ACR. If the queue is
served at a lower rate than ACR - due to resource contention - the unused bandwidth will
be consumed by the network (“use-it-or-lose-it” principle). Using the WFQ scheduler and
assigning an appropriate weight assures that ACR is not falling below MCR.
Multiplexing user cells and FRM cells occurs under control of the ERC unit according to
the behavior defined in the standards.
VS/VD destination behavior is basically to convert the received FRM cells into BRM
cells. The CI/NI and ER fields of the outgoing BRM cells are updated to reflect the
congestion situation of the VD side buffers. The received BRM cells are evaluated and
the ACR is conveyed to the companion virtual source.
In a switch, the VS/VD function is distributed, as shown in
Data Sheet
network and reduces ACR by a factor.
According to the standards, after connection setup, the ICR must be adapted as
follows:
VS/VD Behavior
ICR
=
max MCR min ICR
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Setup
108
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FRTT
TBE
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Figure
Functional Description
3-46.
PXF 4336 V1.1
2001-12-17
ABM-P
(3)