H3C Technologies H3C SecPath F1000-E - Manual (Page 304)

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DiffServ model
The differentiated service (DiffServ) model is a multiple-service model that can satisfy 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
The QoS techniques include traffic classification, traffic policing, traffic shaping, line rate, congestion
management, and congestion avoidance. The firewall supports only traffic policing. The following
sections briefly introduce these QoS techniques.
Applying QoS techniques in a network
Figure 172 Position of the QoS techniques in a network
As shown in Figure 172 , 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 class. Based on classes, you can provide differentiated services.
• Traffic policing—Polices flows entering or leaving a device, and imposes penalties on traffic flows
that exceed the pre-set threshold 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.
• 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, and is usually applied to the
outgoing traffic of a port. When congestion worsens, congestion avoidance reduces the queue
length by dropping packets.