pxf4333 Infineon Technologies Corporation, pxf4333 Datasheet - Page 71

• Manufacturer Part Number: pxf4333
• Description: Abm 3g Atm Buf Fer Manager
• Manufacturer: Infineon Technologies Corporation

A hysteresis control parameter DH
the low threshold TL
DH
An example for the hysteresis mechanism is shown in
When TH is exceeded, a connection specific discard flag is set which is cleared again
when the buffer fill falls below TL. This flag is used by the cell acceptance algorithm to
differentiate between accept state and discard state.
Figure 3-19 Buffer Threshold with Hysteresis
Hysteresis is not used with packet discard and CLP1 discard thresholds.
Hysteresis avoids oscillation effects when the buffer fill is just stable at a certain value
and this value just coincides with a certain threshold. A stable buffer fill occurs when
input and output flow of the buffer are equal. However, due to cell clumping effects the
fill value will vary with a cell jitter in the range 10..100 cells. The hysteresis threshold
difference should be larger than the jitter.
3.4.1.7
The following pseudo-code provides the cell acceptance algorithm of the ABM-3G based
on the parameter set listed in
Data Sheet
TL
i
i
=0 disables the feature.
=
T L i
T H i
TH
B uffe r_size
i
–
Cell Acceptance Algorithm
(
TH
i
»
[
DH
i
from a given high threshold TH
i
+
C ell a ccep tanc e rate is h ig he r than cell em ission ra te
1
]
“DH” on Page 207
)
Chapter
, with DH
T H i is re ach ed, c ells of tra ffic class i a re d isca rd ed
= > C e ll acce ptan ce rate is redu ced ,
i
is provided per traffic class i. It is used to calculate
3.4.1.3.
i
ranging from 1 to 7.
71
som e con nectio ns red uce ra te
= > buffe r fill falls
provides the programming details.
b uffer falls b elow T Li
ce lls of traffic class i a re acce pted
= > em ptyin g rate sinks,
b uffer falls b elow T H i
ce lls of traffic class i a re still dis carde d
i
according to:
Figure 3-19
s et d is card flag
Functional Description
cle ar disca rd flag
below.
tim e
PXF 4333 V1.1
2001-12-17
ABM-3G