Traffic Policing - HP A5120 EI Series Configuration Manual

Complicated evaluation
You can set two token buckets, bucket C and bucket E, to evaluate traffic in a more complicated
environment and achieve more policing flexibility. For example, traffic policing uses the following
parameters:
CIR: Rate at which tokens are put into bucket C. It sets the average packet transmission or

forwarding rate allowed by bucket C.
 CBS: Size of bucket C, which specifies the transient burst of traffic that bucket C can forward.
 Peak information rate (PIR): Rate at which tokens are put into bucket E, which specifies the average
packet transmission or forwarding rate allowed by bucket E.
 Excess burst size (EBS): Size of bucket E, which specifies the transient burst of traffic that bucket E
can forward.
CBS is implemented with bucket C, and EBS with bucket E. In each evaluation, packets are measured
against the buckets and colored following these rules:
 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.


Traffic policing

NOTE:
Traffic policing can police only inbound 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. The network resources
and the interests of the carrier are protected. 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 Schematic diagram for traffic policing
Packets to be sent
through this interface
Tokens are put into the
bucket at the set rate
Packet
classification
Token
bucket
Packets dropped
Packets sent
Queue
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