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MGS3700-12C User’s Guide
227
CHAPTER 22
Queuing Method
This chapter introduces the queuing methods supported.
22.1 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.
22.1.1 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.
22.1.2 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.