PXB4330 Datasheet, PDF (57/201 Pages) Infineon Technologies AG – ICs for Communications

PXB 4330
Operational Description
• Assign minimum weight factor to this queue
• Take the bandwidth of the queue into account using formulas (1) and (2) as if for a
non-real-time connection
• Assign UBR connections to this queue without any further CAC
Note: EPD/PPD functionality is offered by the ABM on a per-VC basis. Hence, these
functions can be supported also for UBR connections sharing one queue.
Note: In addition to the bandwidth reservation, buffer space must be assigned by the ap-
propriate setting of thresholds.
4.7.1 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 kbit/s 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 kbit/s with the weight factors 1/n, n₁₀₀ = 3146 and n₂₀ = 15730, respectively. The
100 kbit/s connections would be used for the downstream direction, and the 20 kbit/s
connections for the upstream direction. Table 4-1 provides the maximum number of con-
nections possible on each PHY.
Table 4-1 Number of Possible Connections per PHY
PHY
GR = 100 kbit/s GR = 20 kbit/s
34 Mbit/s 349
1747
8 Mbit/s 80
403
0.6 Mbit/s 6
30
Data Sheet
4-57
09.99