Queuing Method; Introduction To Queuing; Strict Priority Queuing (Spq); Table 44 Physical Queue Priority - ZyXEL Communications GS-3012F User Manual

GS-3012/GS-3012F User's Guide
This chapter introduces SPQ and WFQ.

18.1 Introduction to Queuing

Queuing is used to help solve performance degradation when there is network congestion. Use
the Queuing Method screen to configure queuing algorithms for outgoing traffic. See also
Priority Queue Assignment in Switch Setup and 802.1p Priority in Port Setup for related
information.
Queuing algorithms allow switches to maintain separate queues for packets from each
individual source or flow and prevent a source from monopolizing the bandwidth.
The switch has eight physical queues, Q0 to Q7. Q7 has the highest priority and Q0 has the
lowest.

Table 44 Physical Queue Priority

QUEUE
Q7
Q6
Q5
Q4
Q3
Q2
Q1
Q0

18.1.1 Strict Priority Queuing (SPQ)

Strict Priority Queuing (SPQ) services queues based on priority only. As traffic comes into the
switch, traffic on the highest priority queue, Q7 is transmitted first. When that queue empties,
traffic on the next highest-priority queue, Q6 is transmitted until Q6 empties, and then traffic is
transmitted on Q5 and so on. If higher priority queues never empty, then traffic on lower
priority queues never gets sent. SPQ does not automatically adapt to changing network
requirements.
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Queuing Method

PRIORITY
8 (highest)
7
6
5
4
3
2
1 (lowest)
H A P T E R

Chapter 18 Queuing Method

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