
PXB 4330
Operational Description
Data Sheet
4-58
09.99
For example, if the maximum number of connections for each Subscriber is fixed (such
as 5 data connections), the queues can be pre-configured for each Subscriber so that
only the LCI assignment must be changed when a connection is setup or released.
4.8
Programming of the Peak Rate Limiter / PCR Shaper
For each queue, an optional peak rate shaper can be programmed. The possible peak
rate values can be determined with:
r
m
in
m
r
=
[cells/s]
(3)
with
m
∈
{1, 2, 3, ...63488} the rate factor
rmin depending on the total throughput, i.e. the clock frequency:
rmin
=
[cells/s]
(4)
4.9
Scheduler Output Rate Calculation Example
The parameters of the Schedulers must be chosen in relation to the transmission rates
of the PHYs, respectively. That means for a Scheduler which transmits in the upstream
direction such as 150 Mbit/s output rate and for a Scheduler which transmits in the down-
stream direction such as 6 Mbit/s output rate for a ADSL device (as depicted in
Figure
4-2
). Within the ABM, the Scheduler output rate is represented by the two parameters:
IntRate(14:0), page 73 and FracRate(7:0), page 70. These parameters are without di-
mension and thus only indirectly represent the output rate. The following part declares
how to derive the two parameters by a time parameter T and the correlation between
these parameters and the output rate R:
T
=
[without dimension]
(5)
with
ABM core clock SYSCLK = [1/s]
Scheduler output rate R = [cells/s]
IntRate
=
(6)
with
int(T) is integer part of T
FracRate
=
(7)
-------------
2
16
×
SYSCLK
2
19
------------------------
SYSCLK
32 cells
1
–
R
×
------------------------------------
int T
T
int T
–
{
}
256
1
+
×