Traffic Classification Overview; Priority - 3Com MSR 50 Series Configuration Manual

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Traffic Classification
Overview
Traffic classification

Priority

T C
RAFFIC LASSIFICATION
S
AND HAPING
Traffic classification is the prerequisite and foundation for differentiated services,
which uses certain rules to identify the packets with certain features.
To discriminate flows, you can set traffic classification rules using the priority bits
of ToS (type of service) field in the IP packet header. Alternatively, the network
administrator may define a traffic classification policy, for instance, integrating
information such as source IP address, destination IP address, MAC address, IP
protocol, or port number of the applications to classify the traffic. In general, it can
be a narrow range defined by a quintuple (source IP address, source port number,
destination IP address, destination port number and the Transport Protocol), or can
be all packets to a network segment.
In general, while packets being classified on the network border, the precedence
bits in the ToS byte of IP header are set so that IP precedence can be used as a
direct packet classification standard within the network. The queuing technologies
can use IP precedence to handle the packets. Downstream network can receive
the packets classification results from upstream network selectively, or re-classify
the packets with its own standard.
Traffic classification is used to provide differentiated service, so it must be
associated with certain kinds of traffic policing or resource-assignment
mechanisms. To adopt what kind of traffic policing action will depend on the
current stage and load status of the network. For example, to police the packets
according to the committed rate when they enter the network, to make traffic
shaping before they flow out the nodes, to perform queuing management in the
event of congestion and to employ congestion avoidance when congestion
becomes worse.
Several priorities are described as follows:
, P
OLICING
,