pxf4336 Infineon Technologies Corporation, pxf4336 Datasheet - Page 79

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

IF
THEN
ELSE
3.4.1.7.6 ABR Congestion Indication Support
ExceedCiGlobal =
ExceedCiSB =
ExceedCiQueue =
See
3.4.1.8
The SB congestion indication mechanism is provided to support external flow control
based on Dynamic Bandwidth Allocation (DBA) algorithms. These algorithms allocate
bandwidth in aggregates often referred to as pipes. Several pipes are assumed to
compete for bandwidth on a shared resource bottleneck. The demand for bandwidth of
each individual pipe is monitored and a corresponding share of the resource is
dynamically allocated to the pipe. Several variants of this algorithm have been reported,
supporting fairness and QoS requirements across the bottleneck. Examples of DBA
applications are
• Internal flow control across switching fabrics in an input/output buffered switch
• Point-to-multipoint traffic aggregation, e.g. in an ATM Passive Optical Network
In the context of the ABM-P, a pipe is implemented by a scheduler block. Remember that
the SB rate can be changed flexibly, on the fly. In order to monitor the congestion in an
SB, a set of four congestion indication thresholds have been defined per SB. The
crossing of these thresholds is indicated in a bitmap which can be accessed externally.
Data Sheet
(APON) scenario
Figure 4-9
(ExceedMaxBuffer = FALSE) AND
(ExceedMaxQueueLimit = FALSE) AND
(ExceedMaxNg = FALSE) AND
(ExceedCLP1 = FALSE) AND
(CellAcceptedByEPD = TRUE) AND
(CellAcceptedByPPD = TRUE) AND
(CellAcceptedByHyst = TRUE)
BufferIncomingCell
DiscardIncomingCell
IF
THEN
IF
THEN
SB Congestion Indication Mechanism
for an example of threshold configuration.
PPDen AND UserToUserCell AND (EndOfPacket = FALSE)
DiscardRestOfPacket = TRUE
PPDen = FALSE AND UserToUserCell AND ExceedMaxNg
DiscardRestOfPacket = TRUE
(BufferOccNg >= BufCiCLP1)
[(SBOccNg >= SBCiCLP1) AND (QID != 0)]
(QueueLength >= QueueCiCLP1)
79
Functional Description
PXF 4336 V1.1
2001-12-17
ABM-P