PXF4333 Datasheet, PDF (76/361 Pages) Infineon Technologies AG – ABM 3G ATM Buf fer Manager

3.4.2 Queue Scheduler
ABM-3G
PXF 4333 V1.1
Functional Description
3.4.2.1 Functional Overview
The basic function of the hierarchical Queue Scheduler (QS) is to properly allocate cell
transmission slots to scheduler blocks and within those to queues, enabling them to send
buffered cells. Thereby, the QS allocates the bandwidth resources needed to fulfill the
specific service guarantees of individual connections.
Internally, the QS functions are implemented by two basic building blocks: 128 identical
scheduler blocks (SB) and a subsequent round robin scheduler (SBS) as depicted in
Figure 3-21. In addition to these, a prioritized empty cell generator queue (for SDRAM
refresh) and a Common Real-Time (CRT) queue which also has priority over the SBS,
are provided. These two queues are assumed to be rate limited. Section 4.2.2.4 and
Section 4.2.2.3 respectively provide the details on the programming of these queues.
•
Empty Cell Cycles
Common RT Queue
SB0
R
R
Buffer
Manager
W
F
Q
SBS
R
R
UTOPIA
SB127
R
R
W
F
Q
R
R
Figure 3-21 Functional Structure of the Hierarchical Queue Scheduler
In summary, the Queue Scheduler calculates a QID for each cell emission opportunity.
Data Sheet
76
2001-12-17