Huawei Quidway S7700 Configuration Manual - Qos page 55

Quidway S7700 Smart Routing Switch
Configuration Guide - QoS
The S7700 supports the single token bucket and dual token buckets.
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Traffic Policing Features Supported by the S7700
The S7700 supports the following traffic policing features:
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Issue 01 (2011-07-15)
Single token bucket
The single token bucket technology uses the following parameters:
– Committed burst size (CBS): indicates the maximum volume of traffic that bursts in
bucket C, in bytes.
– Committed information rate (CIR): indicates the rate of tokens that are put into bucket
C, that is, the average traffic rate allowed by bucket C, in kbit/s.
If there are sufficient tokens in the bucket, packets are forwarded. At the same time, the
number of tokens in the bucket decreases based on the length of the packets. If there are
no tokens in the bucket, packets are discarded.
Dual token buckets
The dual token bucket technology uses the following parameters in addition to the CIR and
CBS:
– Peak burst size (PBS): indicates the maximum volume of traffic that bursts and exceeds
the CBS in bucket P, in bytes.
– Peak information rate (PIR): indicates the rate of tokens that are put into bucket P, that
is, the average traffic rate allowed by bucket P, in kbit/s.
For the dual token buckets:
– The service traffic that less than the CIR value is colored green and is allowed to pass
through.
– The service traffic that exceeds the PIR value is colored red and is discarded.
– The service traffic that ranges from the CIR value to the PIR value is colored yellow
and is discarded when congestion occurs.
Interface-based traffic policing.
Interface-based traffic policing controls all incoming traffic on an interface regardless of
packet types and discards the excess traffic, limiting traffic within a proper range and
protecting network resources and carriers' interests.
Traffic policing based on a traffic classifier
Traffic policing based on a traffic classifier limits the rate of the traffic matching a traffic
classifier after traffic classification is performed on the S7700. The S7700 limits the rate
of incoming traffic and discards the traffic that exceeds the rate limit, limiting traffic within
a proper range and protecting network resources and carriers' interests. Traffic policing
based on a traffic classifier uses dual token buckets.
After traffic policing based on a traffic classifier is configured on the S7700, the CAR can
be performed twice for upstream flows. The S7700 first sets the CAR for the upstream
flows that matches a traffic classifier, and then aggregates all the upstream flows and uses
the CAR to limit the flows. The upstream flows refer to the incoming service flows matching
the same traffic classifier in a traffic policy. The traffic classifier is bound to a traffic
behavior containing aggregate CAR.
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2 Traffic Policing and Traffic Shaping Configuration
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