H3C Technologies H3C WX6000 Series Access Controllers - Manual (Page 433)

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Excess burst size (EBS)
Two token buckets are used in this evaluation. Their rates of putting tokens into the buckets are CIR and
PIR respectively, and their sizes are CBS and EBS respectively (the two buckets are called C bucket
and E bucket respectively for short), representing different permitted burst levels. In each evaluation,
you can implement different regulation policies in different conditions, including “enough tokens in C
bucket”, “insufficient tokens in C bucket but enough tokens in E bucket” and “insufficient tokens in both
C bucket and E bucket”.
Traffic Policing
The typical application of traffic policing is to supervise the specification of certain traffic into the network
and limit it within a reasonable range, or to "discipline" the extra traffic. In this way, the network
resources and the interests of the operators are protected. For example, you can limit HTTP packets to
be within 50% of the network bandwidth. If the traffic of a certain connection is excess, traffic policing
can choose to drop the packets or to reset the priority of the packets.
Traffic policing is widely used in policing the traffic into the network of internet service providers (ISPs).
Traffic policing can classify the policed traffic and perform pre-defined policing actions based on
different evaluation results. These actions include:
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Forwarding conforming packets or non-conforming packets.
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Dropping conforming or non-conforming packets.
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Marking a conforming packet with a new 802.1p precedence value and forwarding the packet.
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Marking a conforming packet with a new IP precedence value and forwarding the packet.
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Marking a conforming packet or a non-conforming packet with a new DSCP precedence value and
forwarding the packet.
Line Rate
Port rate limiting refers to limiting the total rate of inbound or outbound packets on a port.
Port rate limiting can be implemented through token buckets. That is, if you perform port rate limiting
configuration for a port, the token bucket determines the way to process the packets to be sent by this
port or packets reaching the port. Packets can be sent or received if there are enough tokens in the
token bucket; otherwise, they will be dropped.
Compared to traffic policing, port rate limiting applies to all the packets passing a port. It is a simpler
solution if you want to limit the rate of all the packets passing a port.