PXB4330 Datasheet, PDF (40/201 Pages) Infineon Technologies AG – ICs for Communications

PXB 4330
Functional Description
The WFQ Multiplexer permits sharing of the remaining bandwidth by the non-real-time
connections. The WFQ Multiplexer has a maximum of 1023 inputs with a weight factor
assigned to each input. It distributes the remaining bandwidth among active or occupied
queues according to the weight factors.
The WFQ Multiplexer has the following properties:
• Fair distribution of bandwidth
• Guaranteed Quality of Service (QoS) for each connection (minimum service rate,
bounded delay)
• Load conserving, that is, the output is always 100%
• Protection against misbehaving users (exceeding their bandwidth budget).
These are important, for example, in data connections having start-stop behavior. An ex-
ample is shown in Figure 3-5. The duration of the data bursts and the idle periods vary
over a wide range.
bit rate
time
Figure 3-5 Data Traffic Example
For non-real-time connections, normally one queue is assigned to each connection, that
is, per-VC queuing. During idle periods, the queues will run empty, and, when a data
burst is sent, they fill up again. The WFQ Multiplexer automatically deals with the varying
load situations and always distributes the bandwidth according to the weight factors. An
example of a Scheduler with one real-time queue (Queue 1) and nine non-real-time
queues (Queue 2 through Queue 10) is shown in Figure 3-6. Queue 1 is shared by a
number of connections with different bit rates.
Data Sheet
3-40
09.99