3Com MSR 50 Series Configuration Manual page 1626

1626 C 83: Q S O
HAPTER O VERVIEW
and congestion. Same as traffic policing, traffic shaping is implemented at the
IP layer.
Congestion management: handles resource competition during network
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congestion. Generally, it stores the packets in the queue first, and then takes a
dispatching algorithm to assign the forwarding sequence of packets.
Congestion avoidance: Exceeding congestion consumes network resources.
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Congestion avoidance can monitor the usage status of network resources, and
as congestion becomes worse, actively take the policy of dropping packets
through adjusting traffic to resolve the overloading of the network.
Among those traffic management technologies, traffic classification is the basis. It
is a prerequisite for differentiated services, which identifies the interested packets
with certain matching rule. As for traffic policing, traffic shaping, congestion
management and congestion avoidance, they implement management to
network traffic and allocated resources from different aspects respectively to
realize the differentiated service.
Normally, QoS provides the following functions:
Traffic classification
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Access control
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Traffic policing and shaping
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Congestion management
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Congestion avoidance
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