PXF4333 Datasheet, PDF (74/361 Pages) Infineon Technologies AG – ABM 3G ATM Buf fer Manager

ABM-3G
PXF 4333 V1.1
Functional Description
3.4.1.7.5 Overall Cell Acceptance Algorithm
The overall decision whether an arriving cell is buffered is based on the results of the
previous algorithms. The arriving cell can only be accepted if all algorithms would accept
the cell and if buffer space is available. To obtain the overall decision whether a correctly
received cell is finally buffered the following algorithm applies:
IF
THEN
ELSE
(ExceedMaxBuffer = FALSE) AND
(ExceedMaxQueueLimit = FALSE) AND
(ExceedMaxNg = FALSE) AND
(ExceedCLP1 = FALSE) AND
(CellAcceptedByEPD = TRUE) AND
(CellAcceptedByPPD = TRUE) AND
(CellAcceptedByHyst = TRUE)
BufferIncomingCell
DiscardIncomingCell
IF PPDen AND UserToUserCell AND (EndOfPacket = FALSE)
THEN DiscardRestOfPacket = TRUE
IF PPDen = FALSE AND UserToUserCell AND ExceedMaxNg
THEN DiscardRestOfPacket = TRUE
See Figure 4-9 for an example of threshold configuration.
3.4.1.8 Statistical Counters
In addition to the occupancy counters, which may also be used for statistical purposes,
the ABM-3G device provides several dedicated counters for statistics purposes. These
are summarized in Table 3-20:
•
Table 3-20 Statistical Counters
Name
Comment
Reg 17 UMAC/DMAC
Reg 18 UMIC/DMIC
16 Maximum buffer occupancy value
since last readout
16 Minimum buffer occupancy value
since last readout
Data Sheet
74
2001-12-17