PXF4336 Datasheet, PDF (69/425 Pages) Infineon Technologies AG – ABM Premium ATM Buf fer Manager

ABM-P
PXF 4336 V1.1
Functional Description
• DH
Delta Hysteresis is a traffic class specific factor applied to all maximum thresholds.
The description of the hysteresis mechanism in Section 3.4.1.6.5 provides the
details.
3.4.1.3.2 Congestion Indication Thresholds
Congestion indication thresholds are provided to support external flow control
algorithms.
• ABR Congestion Indication
Some thresholds are used to indicate congestion to ABR connections (ABRen=’1’) on
a global buffer, scheduler and queue basis. By exceeding one or a combination of
these thresholds EFCI bits of user cells and NI and CI bits of RM cells are set
appropriately. NI is set in a slightly congested situation. NI and CI are set in a heavy
congested situation. Chapter 3.5.1 provides the details on the ABR support.
• SB Congestion Indication
If the scheduler low and high priority buffer occupation exceeds the respective
thresholds the corresponding threshold crossing indication bits for these scheduler
blocks are set to ’1’. The indication is used for the support of dynamic bandwidth
allocation (DBA) protocols. Chapter 3.4.1.8 provides the details on DBA support.
• Queue Congestion Indication
These per queue thresholds generate a queue specific congestion indication that is
provided to the QCI interface and translated into a serial bit pattern to be processed
by external devices (downstream only).
3.4.1.3.3 Backpressure Thresholds
• UTOPIA Backpressure Thresholds
These thresholds (four in upstream and four in downstream direction) are global
thresholds with respect to the cell buffer fill level and result in backpressure of specific
port groups of the respective UTOPIA receive interface.
3.4.1.4 Counter Classification
The ABM-P Buffer Manager contains the following counter types
• Occupancy Counters
These counters reflect the current buffer state and are basic elements in discard,
congestion indication and backpressure mechanisms.
• Statistics Counters
These counters are used for measurements and statistics. Refer also to
Chapter 3.4.1.9.
Data Sheet
69
2001-12-17