Major Traffic Control Techniques - 3Com 5500-EI PWR Install Manual

Besides the traditional applications such as WWW, E-mail, and FTP, new services are
developed on the Internet, such as tele-education, telemedicine, video telephone,
videoconference and Video-on-Demand (VoD). Enterprise users expect to connect their
regional branches together using VPN techniques for coping with daily business, for
instance, accessing databases or manage remote equipments through Telnet.
All these new applications have one thing in common, that is, they have special
requirements for bandwidth, delay, and jitter. For instance, bandwidth, delay, and jitter are
critical for videoconference and VoD. As for other applications, such as transaction
processing and Telnet, although bandwidth is not as critical, a too long delay may cause
unexpected results. That is, they need to get serviced in time even if congestion occurs.
Newly emerging applications demand higher service performance from IP networks. In
addition to simply delivering packets to their destinations, better network services are
demanded, such as allocating dedicated bandwidth, reducing packet loss ratio, avoiding
congestion, regulating network traffic, and setting priority of the packets. To meet those
requirements, the network should be provided with better service capability.

Major Traffic Control Techniques

Figure 1-1 End-to-end QoS model
As shown in the figure above, traffic classification, traffic policing, traffic shaping,
congestion management, and congestion avoidance are the foundations for a network to
provide differentiated services. They are described as follow:
Traffic classification identifies traffic based on certain matching rules. It is a
prerequisite for differentiated services and is usually applied in the inbound direction
of a port.
Traffic policing confines traffic to a specific specification and is usually applied in the
inbound direction of a port. You can configure restriction or penalty measures against
the exceeding traffic to protect carrier benefits and network resources.
Traffic shaping adapts output traffic rate usually to the input capability of the receiving
device to avoid packet drop and port congestion. Traffic shaping is usually applied in
the outbound direction of a port.
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