Extreme Networks ExtremeWare XOS 10.1, Manual

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84 ExtremeWare XOS 10.1 Concepts Guide
Quality of Service (QoS)
Configuring QoS
To configure QoS, you define how your switch responds to different categories of traffic by creating and
configuring QoS profiles. You then group traffic into categories (according to application, as previously
discussed) and assign each category to a QoS profile. Configuring QoS is a three-step process:
1 Configure the QoS profile.
QoS profile —A class of service that is defined through minimum and maximum bandwidth
parameters, and prioritization settings. The bandwidth and level of service that a particular type of
traffic or traffic grouping receives is determined by assigning it to a QoS profile.
2 Create traffic groupings.
Traffic grouping
—A classification or traffic type that has one or more attributes in common. These
can range from a physical port to IP layer 4 port information. You assign traffic groupings to QoS
profiles to modify switch forwarding behavior. Traffic groupings transmitting out the same port that
are assigned to a particular QoS profile share the assigned bandwidth and prioritization
characteristics, and hence share the class of service.
3 Monitor the performance of the application with the QoS monitor to determine whether the policies
are meeting the desired results.
The next sections describe each of these QoS components in detail.
QoS Profiles
A QoS profile defines a class of service by specifying traffic behavior attributes, such as bandwidth. The
parameters that make up a QoS profile include:
• Minimum bandwidth —The minimum percentage of total link bandwidth that is reserved for use by
a hardware queue on a physical port. Bandwidth unused by the queue can be used by other queues.
The minimum bandwidth for all queues should add up to less than 100%. The default value on all
minimum bandwidth parameters is 0%.
• Maximum bandwidth
—The maximum percentage of total link bandwidth that can be transmitted
by a hardware queue on a physical port. The default value on all maximum bandwidth parameters
is 100%.
• Priority —The level of priority assigned to a hardware queue on a physical port. There are eight
different available priority settings. By default, each of the default QoS profiles is assigned a unique
priority. You would use prioritization when two or more hardware queues on the same physical port
are contending for transmission on the same physical port, only after their respective bandwidth
management parameters have been satisfied. If two hardware queues on the same physical port have
the same priority, a round-robin algorithm is used for transmission, depending on the available link
bandwidth.
Web browsing Minimum bandwidth for critical applications, maximum bandwidth for non-critical
applications
File server Minimum bandwidth
Table 11: Traffic Type and QoS Guidelines
Traffic Type Key QoS Parameters