R0106-HP MSR Router Series ACL and QoS Configuration Guide(V7)

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• Traffic shaping.
• Rate limit.
• Congestion management.
• Congestion avoidance.
The following section briefly introduces these QoS techniques.
All QoS techniques in this document are based on the DiffServ model.
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 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 and imposes penalties to prevent aggressive use of network resources.
You can apply traffic policing to both incoming and outgoing traffic of a port.
• Traffic shaping—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.
• Congestion management—Provides a resource scheduling policy to determine the packet
forwarding sequence when congestion occurs. Congestion management usually applies to the
outgoing traffic of a port.
• Congestion avoidance—Monitors the network resource usage. It is usually applied to the outgoing
traffic of a port. When congestion worsens, congestion avoidance reduces the queue length by
dropping packets.
QoS processing flow in a device
Figure 3 briefly describes how the QoS module processes traffic:
1. Traffic classifier identifies and classifies traffic for subsequent QoS actions.