H3C Technologies H3C WX6000 Series Access Controllers - Manual (Page 428)

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Traffic Classification, Traffic Policing, and Line
Rate Configuration
When configuring traffic classification, traffic policing, and line rate, go to these section for information
you are interested in:
z
Traffic Classification Overview
z
Traffic Policing and Line Rate Overview
z
Traffic Evaluation and Token Bucket
z
Line Rate Configuration
z
Displaying and Maintaining Line Rate
Traffic Classification Overview
Traffic Classification
Traffic classification is to identify packets conforming to certain characters according to certain rules. It
is the basis and prerequisite for proving differentiated services.
A traffic classification rule can use the precedence bits in the type of service (ToS) field of the IP packet
header to identify traffic with different precedence characteristics. A traffic classification rule can also
classify traffic according to the traffic classification policy set by the network administrator, such as the
combination of source addresses, destination addresses, MAC addresses, IP protocol or the port
numbers of the applications. Traffic classification is generally based on the information in the packet
header and rarely based on the content of the packet. The classification result is unlimited in range.
They can be a small range specified by a quintuplet (source address, source port number, protocol
number, destination address, and destination port number), or all the packets to a certain network
segment.
Generally, the precedence of bits in the ToS field of the packet header is set when packets are classified
on the network border. Thus, IP precedence can be used directly as the classification criterion inside the
network. Queue techniques can also process packets differently according to IP precedence. The
downstream network can either accept the classification results of the upstream network or re-classify
the packets according to its own criterion.
The purpose of traffic classification is to provide differentiated services, so traffic classification is
significant only when it is associated with a certain traffic control or resource assignment action. The
specific traffic control action to be adopted depends on the phase and the current load status. For
example, when the packets enter the network, traffic policing is performed on the packets according to
CIR; before the packets flow out of the node, traffic shaping is performed on the packets; when
congestion occurs, queue scheduling is performed on the packets; when congestion get worse,
congestion avoidance is performed on the packets.
Priority
The following describes several types of precedence: