PXF4333 Datasheet, PDF (117/361 Pages) Infineon Technologies AG – ABM 3G ATM Buf fer Manager

ABM-3G
PXF 4333 V1.1
Operational Description
For the definition of the Guaranteed Rate, see Table 3-24. Mathematically, the CAC can
be reduced to the following formulas:
For all connections make sure that no overbooking of the configured scheduler output
rate CCR_out occurs, i.e.:
Ã¥^GCRi ^{= CCR}out
(29)
i
For real-time connections, (CBR, rt-VBR) Equation (29) is the only condition required.
For non-real-time connections or connections using the WFQ scheduler, additional con-
ditions must be fulfilled.
VBR and UBR+ connections must be setup in per VC queueing configurations, that is,
an empty queue must be found for the connection. The Guaranteed Rate determines the
weight of the queue.
4.2.5.1 Bandwidth Reservation Example
As an example, an access network multiplexer is assumed with ADSL lines and an E3
uplink. CBR and UBR+ connections are supported. A minimum Guaranteed Rate of
GR_min = 19.2 Kbps is selected. This allows GR up to 314.57 Mbit/s with increasing gran-
ularity for higher values.
This behavior is well suited to the Guaranteed Rates which are minimum or sustainable
rates. The values for MCR and SCR will be well below 10 Mbit/s for public networks. In
high speed LANs with high MCR and SCR values, a higher minimum rate could be
selected.
Additionally, it is assumed that three types of line interfaces (PHY) exist in the system:
34 Mbit/s for the uplink, ADSL rates of 8 Mbit/s downstream, and 0.6 Mbit/s upstream.
For each PHY, a maximum possible weight factor 1/n exists: n_max = 9, n_max= 39, and n_max
= 524, respectively.
Two types of non-real-time connection are defined with Guaranteed Rates of 100 kbit/s
and 20 Kbps with the weight factors 1/n, n₁₀₀ = 3146 and n₂₀ = 15730, respectively. The
100 Kbps connections would be used for the downstream direction, and the 20 Kbps
connections for the upstream direction. Table 4-8 provides the maximum number of con-
nections possible on each PHY.
Data Sheet
117
2001-12-17