H3C LS-3100-52P-OVS-H3 Operation Manual page 1255

This section is focused on traffic classification, and the subsequent sections will introduce the other
technologies in details.
Traffic Classification
Traffic classification organizes packets with different characteristics into different classes using match
criteria. It is the basis for providing differentiated services.
You can define match criteria based on the IP precedence bits in the type of service (ToS) field of the IP
packet header, or based on other header information such as IP addresses, MAC addresses, IP
protocol field, and port numbers. Contents other than the header information in packets are rarely used
for traffic classification. You can define a class for packets with a common quintuple (source address,
source port number, protocol number, destination address and destination port number), or for all
packets to a certain network segment.
When packets are classified at network boundaries, the precedence bits in the ToS field of the IP packet
header are generally re-set. In this way, IP precedence can be adopted as a classification criterion for
the packets in the network. IP precedence can also be used in queuing to prioritize traffic. The
downstream network can either inherit the classification results from its upstream network or re-classify
the packets according to its own criteria.
To provide differentiated services, traffic classes must be associated with certain traffic control actions
or resource allocation actions. What traffic control actions should be adopted depends on the current
phase and the resources of the network. For example, CIR is adopted to police packets when they enter
the network; generic traffic shaping (GTS) is performed on packets when they flow out of the node;
queue scheduling is performed when congestion happens; congestion avoidance measures are taken
when the congestion deteriorates.
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