ZyXEL Communications GS3700 Series Uživatelská příručka stáhnout pdf (Strana 174)

GS3700/XGS3700 Series User’s Guide 174

CHAPTER 20

Queuing Method

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

Strictly Priority (SP) 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 (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. By default, the weight for Q0 is

1, for Q1 is 2, for Q2 is 3, and so on.

The weights range from 1 to 15 and the actual guaranteed bandwidth is calculated as follows:

Weight x 2 KB

If the weight setting is 5, the actual quantum guaranteed to the associated queue would be as

follows:

5 x 2KB = 10 KB

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ZyXEL Communications GS3700 Series Uživatelská příručka Strana 174