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CBS is implemented with bucket C, and EBS with bucket E. When only the CIR is used for traffic
evaluation, packets are measured against the following bucket scenarios:
• If bucket C has enough tokens, packets are colored green.
• If bucket C does not have enough tokens but bucket E has enough tokens, packets are colored
yellow.
• If neither bucket C nor bucket E has sufficient tokens, packets are colored red.
When both CIR and PIR are used to evaluate traffic, bucket P, which is equal to the sum of the CBS and
EBS in size, is introduced. In this case, packets are measured against the following bucket scenarios:
• If both bucket C and bucket P have enough tokens, packets are colored green.
• If bucket C does not have enough tokens but bucket P has enough tokens, packets are colored
yellow.
• If bucket P does not have enough tokens, packets are colored red.
You can configure traffic control policies for packets of different colors by using the traffic policing
feature.
Traffic policing
Traffic policing supports policing the inbound traffic and the outbound traffic.
A typical application of traffic policing is to supervise the specification of certain traffic entering a
network and limit it within a reasonable range, or to "discipline" the extra traffic to prevent aggressive
use of network resources by a certain application. For example, you can limit bandwidth for HTTP
packets to less than 50% of the total. If the traffic of a certain session exceeds the limit, traffic policing can
drop the packets or reset the IP precedence of the packets. Figure 8 sho
ws an example of policing
outbound traffic on an interface.
Figure 8 Traffic policing
Traffic policing is widely used in policing traffic entering the networks of ISPs. It can classify the policed
traffic and take pre-defined policing actions on each packet depending on the evaluation result:
• Forwarding the packet if the evaluation result is "conforming."
• Dropping the packet if the evaluation result is "excess."
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