Chapter 15: Quality Of Service; Overview Of Policy-Based Quality Of Service - Extreme Networks ExtremeWare XOS Guide Manual

15 Quality of Service
This chapter covers the following topics:
Overview of Policy-Based Quality of Service on page 289
●
Applications and Types of QoS on page 290
●
Configuring QoS on page 292
●
QoS Profiles on page 293
●
Traffic Groupings on page 295
●
Verifying QoS Configuration and Performance on page 307
●
Guidelines for Configuring QoS on page 309
●
Egress Traffic Rate Limiting—BlackDiamond 8800 Family of Switches and Summit X450 Switch Only
●
on page 309
Bi-Directional Rate Shaping—BlackDiamond 10K Switch Only on page 310
●
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 (VoIP) 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 BlackDiamond 8800 family of switches (formerly known as Aspen) and the Summit X450
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.
ExtremeWare XOS 11.3 Concepts Guide
289