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QoS features
QoS policies
In data communications, Quality of Service (QoS) provides differentiated service guarantees for
diversified traffic in terms of bandwidth, delay, jitter, and drop rate, all of which can affect QoS.
By associating a traffic behavior with a traffic class in a QoS policy, you apply QoS actions in the
traffic behavior to the traffic class.
Traffic class
A traffic class defines a set of match criteria for classifying traffic.
Traffic behavior
A traffic behavior defines a set of QoS actions to take on packets.
QoS policy
A QoS policy associates traffic classes with traffic behaviors and performs the actions in each
behavior on its associated traffic class.
Applying a QoS policy
You can apply a QoS policy to the following destinations:
•
Interface
—The QoS policy takes effect on the traffic sent or received on the interface. The QoS
policy applied to the outgoing traffic on an interface does not regulate local packets. Local
packets refer to critical protocol packets sent by the local system for operation maintenance.
The most common local packets include link maintenance packets.
•
VLAN
—The QoS policy takes effect on the traffic sent or received on all ports in the VLAN. QoS
policies cannot be applied to dynamic VLANs, for example, VLANs created by GVRP.
•
Globally
—The QoS policy takes effect on the traffic sent or received on all ports.
Release 3111P02 does not support applying a QoS policy to the outbound direction of an interface, a
VLAN, or globally.
Hardware queuing
Congestion occurs on a link or node when the traffic size exceeds the processing capability of the
link or node. Congestion is unavoidable in switched networks or multiuser application environments.
To improve the service performance of your network, implement congestion management policies.
Queuing is a typical congestion management technique. SP, WRR, and WFQ are typical queuing
methods.
