Qtech QSW-2800v2 [120/230] Chapter5

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Chapter5

QoS Configuration

5.1 Summary

This chapter introduces configurations of QSW-2800 Switch QoS, including its

background and basic configuration process.

This chapter includes the following section.

Content

Page

5.1 Summary

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5.2 Queue Scheduling and Congestion Control

Configuration

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5.2 Queue Scheduling and Congestion Control Configuration

5.2.1 Queue Scheduling and Congestion Control Introduction

Congestion Influence

Congestion is a phenomenon that shortage supply of resources causes forwarding

rate decreased and introduction of additional delay.

The bottleneck of link bandwidth will cause congestion. The shortage of resource

which is used to deal with data transmitting will cause congestion such as shortage of

allocated processor time, buffer and memory. Under current complex network

environment with variety of services application, congestion is very common.

Congestion may cause a series of negative effect.

 Congestion increases delay and jitter of message transmission. Excessive delay

will cause packet retransmission.

 Congestion decreases effective throughput of network. It results in utilization rate

of network resource decreasing.

 Serious congestion will consume a large amount of network resource (especially

the storage resources). Unreasonable resource allocation may even lead to

system collapse because of resource deadlock.