Extreme Networks ExtremeWare XOS 11.1, Manual

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ExtremeWare XOS 11.1 Concepts Guide
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12 Quality of Service
This chapter covers the following topics:
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Overview of Policy-Based Quality of Service on page 201
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Applications and Types of QoS on page 202
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Configuring QoS on page 204
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QoS Profiles on page 205
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Traffic Groupings on page 207
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Verifying QoS Configuration and Performance on page 219
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Guidelines for Configuring QoS on page 220
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Egress Traffic Rate Limiting—Aspen 8810 Switch Only on page 220
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Bi-Directional Rate Shaping—BlackDiamond 10K Switch Only on page 221
Policy-based Quality of Service (QoS) is a feature of ExtremeWare XOS and the Extreme Networks
switch architecture that allows you to specify different service levels for traffic traversing the switch.
Policy-based QoS is an effective control mechanism for networks that have heterogeneous traffic
patterns. Using Policy-based QoS, you can specify the service level that a particular traffic type receives.
Overview of Policy-Based Quality of Service
Policy-based Quality of Service (QoS) is a feature of ExtremeWare XOS and the Extreme Networks
switch architecture that allows you to specify different service levels for traffic traversing the switch.
Policy-based QoS is an effective control mechanism for networks that have heterogeneous traffic
patterns. Using Policy-based QoS, you can specify the service level that a particular traffic type receives.
Policy-based QoS allows you to protect bandwidth for important categories of applications or to
specifically limit the bandwidth associated with less critical traffic.
For example, if voice-over-IP traffic requires a reserved amount of bandwidth to function properly,
using policy-based QoS, you can reserve sufficient bandwidth critical to this type of application. Other
applications deemed less critical can be limited so as to not consume excessive bandwidth.
On the BlackDiamond 10K switch, the switch contains separate hardware queues on every physical
port. On the Aspen 8810 switch, the switch has two default queues (based on flows), and you can
configure up to six additional queues. Each queue is programmed by ExtremeWare XOS with specific
parameters that modify the forwarding behavior of the switch and affect how the switch transmits
traffic for a given queue on a physical port.
The switch tracks and enforces the specified parameters on every queue for every port. When two or
more queues on the same physical port are contending for transmission, the switch prioritizes use so
long as the respective queue management parameters are satisfied. Up to eight queues per port are
available.