Wfq (Weighted Fairness Queue); General; Counters And Flags Used - NEC mPD98410 User Manual

3.6 WFQ (Weighted Fairness Queue)

3.6.1 General

When a cell is output from an output queue, which cell is to be output is determined by the following two
conditions:
<Output cell determining conditions>
(1) The logical output port to output the cell has been determined.
(2) Of the output queues allocated to the determined logical output port, the service class of the queue from
which the cell is taken out has been determined.
Of these conditions, this section explains (2), i.e., how the service class is determined.
determination is called the WFQ (Weighted Fairness Queue).

3.6.2 Counters and flags used

CBR,
Real-time VBR
RM,
Non-real-time VBR
ABR
UBR
The queue of each logical output port of the µ PD98410 has the following four queues of service classes.
• Output queue of CBR/rtVBR class
• Output queue of RM/nrtVBR class
• Output queue of ABR class
• Output queue of UBR class
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CHAPTER 3 FUNCTIONAL OUTLINE
Figure 3-41. Output Queue and Counter
This method of
Priority
Control
High
C
CBR
C
VBR
OUT
C
ABR
C
UBR
Low
Priority