Traffic Policing; Traffic Shaping - 3Com 3C13636 Configuration Manual

3Com Router 3000 Ethernet Family
Configuration Guide
out. Otherwise, it shows that too much tokens have been used, and traffic
specifications are exceeded.
III. Complicated evaluation
Two Token Buckets can be configured to evaluate conditions that are more complex
and to implement more flexible regulation policy. For example, Traffic Policing (TP) has
three parameters, as follows:
CIR (Committed Information Rate)
CBS (Committed Burst Size)
EBS (Excess Burst Size)
It uses two Token Buckets with the token-putting rate of every bucket set as CIR equally,
but with different capabilities: CBS and EBS (CBS < EBS, called C Bucket and E
Bucket), which represents different bursting class permitted. In each evaluation, you
may use different traffic control policies for different situations, such as "C bucket has
enough tokens"; "Tokens of C bucket are deficient, but those of E bucket are enough";
"Tokens of C bucket and E bucket are all deficient".

2.2.2 Traffic Policing

Typically, traffic policing is used to monitor the specification of certain traffic entering the
network and keep it within a reasonable bound, or it will make "penalty" on the
exceeding traffic so as to protect network resources and profits of carriers. For example,
it can restrict HTTP packets to occupy network bandwidth of no more than 50%. Once
finding the traffic of a connection exceeds, it may drop the packets or reset the
precedence of packets.
Traffic policing allows you to define match rules based on IP precedence or DiffServ
code point (DSCP). It is widely used by ISP to police the network traffic. TP also
includes the traffic classification service for the policed traffics, and depending upon the
different evaluation results, it will implement the pre-configured policing actions, which
are described as the following:
Forward: For example, continue to forward the packets evaluated as "conform".
Drop: for example, dropping the packets evaluated as "not conform".
Reset precedence and forward: For example, for packets evaluated "partly
conform", to sign another priority then forward them.
Enter the policing of the next level: Traffic policing can stack gradually with each
class caring and policing objects that are more specific.

2.2.3 Traffic Shaping

Traffic shaping is an active way to adjust the traffic output rate. A typical application is to
control the output traffic with TP index based upon downstream network nodes.
Chapter 2 Traffic Classification, Policing, and Shaping
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