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About Traffic Shaping
About Traffic Shaping
Why Use Traffic Shaping?
Catalyst 4224 Access Gateway Switch Software Configuration Guide
10-2
Traffic shaping allows you to control outgoing traffic on an interface to match the
traffic speed of the remote target interface and to ensure that the traffic conforms
to specific policies. Traffic that adheres to a particular profile can be shaped to
meet downstream requirements, thereby eliminating bottlenecks in topologies
caused by data-rate mismatches.
The primary reasons to use traffic shaping are to control access to available
bandwidth, to ensure that traffic conforms to specific policies, and to regulate the
flow of traffic in order to avoid congestion. Some example reasons for using
traffic shaping follow:
Control access to bandwidth when policy dictates that the average rate of a
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given interface should not exceed a certain rate.
Configure traffic shaping on an interface if you have a network with differing
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access rates. Suppose that one end of the link in a Frame Relay network runs
at 256 kbps and the other end of the link runs at 128 kbps. Sending packets at
256 kbps could cause failure of the applications using the link.
A similar, more complicated case would be a link-layer network giving
indications of congestion with differing access rates on different attached
data terminal equipment (DTE) devices. The network may be able to deliver
more transit speed to a given DTE device at a specific time than at another
time.
If you offer a subrate service, traffic shaping enables you to use the router to
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partition your T1 or T3 links into smaller channels.
Traffic shaping prevents packet loss. Its use is especially important in Frame
Relay networks because the switch cannot determine which packets take
precedence or which packets should be dropped when congestion occurs.
Chapter 10
Traffic Shaping
OL-2031-02
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