Queuing Method; Chapter 20 Queuing Method; Queuing Method Overview; Strictly Priority Queuing - ZyXEL Communications MES-3728 User Manual

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This chapter introduces the queuing methods supported.

20.1 Queuing Method Overview

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.

20.1.1 Strictly Priority Queuing

Strictly 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. SP does not automatically adapt to changing network
requirements.

20.1.2 Weighted Fair Queuing

Weighted Fair Queuing is used to guarantee each queue's minimum bandwidth based on its
bandwidth weight (portion) (the number you configure in the Weight field) when there is
traffic congestion. WFQ is activated only when a port has more traffic than it can handle.
Queues with larger weights get more guaranteed bandwidth than queues with smaller weights.
This queuing mechanism is highly efficient in that it divides any available bandwidth across
the different traffic queues. By default, the weight for Q0 is 1, for Q1 is 2, for Q2 is 3, and so
on. Guaranteed quantum is calculated as Queue Weight x 2048 bytes.
MES-3728 User's Guide

Queuing Method

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