R21xx-HP FlexFabric 11900 ACL and QoS Configuration Guide

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DiffServ model
The differentiated service (DiffServ) model is a multiple-service model that can meet diverse QoS
requirements. It is easy to implement and extend. DiffServ does not signal the network to reserve
resources before sending data, as IntServ does.
All QoS techniques in this document are based on the DiffServ model.
QoS techniques overview
The QoS techniques include traffic classification, traffic policing, traffic shaping, rate limit, congestion
management, and congestion avoidance. The following section briefly introduces these QoS techniques.
Deploying QoS in a network
Figure 2 Position of the QoS techniques in a network
As shown in Figure 2, traffic classification, traffic shaping, traffic policing, congestion management, and
congestion avoidance mainly implement the following functions:
• Traffic classification—Uses certain match criteria to assign packets with the same characteristics to
a traffic class. Based on traffic classes, you can provide differentiated services.
• Traffic policing—Polices flows entering or leaving a device, and imposes penalties on traffic flows
to prevent aggressive use of network resources. You can apply traffic policing to both incoming and
outgoing traffic of a port.
• Traffic shaping—Proactively adapts the output rate of traffic to the network resources available on
the downstream device to eliminate packet drops. Traffic shaping usually applies to the outgoing
traffic of a port.