Intel 480T, User Manual

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C H A P T E R 8 Quality of Service (QoS)
prioritization parameters. The bandwidth management and
prioritization parameters that modify the forwarding behavior of the
switch affect how the switch transmits traffic for a given hardware
queue on a physical port. For bandwidth management, the switch
tracks and enforces the minimum and maximum percentage
utilization transmitted on every hardware queue for every port.
Prioritization is utilized when two or more hardware queues on the
same physical port are contending for transmission so long as their
respective bandwidth management parameters have been satisfied.
Performance Impact
Utilizing any aspect of Policy-based Quality of Service has zero
impact on switch performance. Using even the most complex traffic
groupings is "costless" in terms of switch performance.
Building Blocks
The service that a particular type of traffic or "traffic grouping"
receives is determined by assigning that traffic to a QoS profile. A
QoS profile is characterized by minimum and maximum bandwidth
and prioritization settings that define a desired class of service. The
building blocks are defined as follows:
• Traffic grouping — A method of classifying or grouping traffic
that has one or more attributes in common. These can range from
a physical port to a VLAN to IP Layer 4 port information.
• QoS profile — Defines minimum and maximum bandwidth
parameters as well as prioritization which characterizes a desired
class of service.
• QoS policy — The combination that results from assigning a
traffic grouping to a QoS profile.
Traffic groupings are assigned to QoS profiles to modify switch
forwarding behavior. When assigned to a traffic grouping, the
combination of the traffic grouping and the QoS profile comprise an
example of a single policy that is part of Policy-based QoS. All
traffic groupings that are assigned to a particular QoS profile share
the assigned bandwidth and prioritization characteristics. For
example, two traffic groupings that are assigned to the same QoS
profile that are transmitting out the same port share the class of
service defined by the QoS profile.