Feature Overview
Class-Based Policing allows you to control the maximum rate of traffic transmitted or received on an interface. The Class-Based Policing feature is applied when you attach a traffic policy contain the Class-Based Policing configuration to an interface.
The Class-Based Policing feature performs the following functions:
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Limits the input transmission rate of a class of traffic based on user-defined criteria
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Marks packets by setting COS, QoS group, and DSCP.
Benefits
Bandwidth Management Through Rate Limiting
Class-Based Policing allows you to control the maximum rate of traffic transmitted or received on an interface. Class-Based Policing is often configured on interfaces at the edge of a network to limit traffic into or out of the network. In most Class-Based Policing configurations, traffic that falls within the rate parameters is transmitted, whereas traffic that exceeds the parameters is dropped or transmitted with a different priority.
Packet Marking
Packet marking allows you to partition your network into multiple priority levels or classes of service (CoS). A packet is marked and these markings can be used to identify and classify traffic for downstream devices.
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Use Class-Based Policing to set the IP precedence for packets entering the network. Networking devices within your network can then use the adjusted IP precedence values to determine how the traffic should be treated.
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Use Class-Based Policing to assign packets to a QoS group. The router uses the QoS group to determine how to prioritize packets within the router.
Traffic can be marked without using the Class-Based Policing feature. If you want to mark traffic but do not want to use Class-Based Policing, see the "Marking Network Traffic" module.
Restrictions
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On a Cisco NCS 520 router, Class-Based Policing can monitor Cisco Express Forwarding (CEF) switching paths only. In order to use the Class-Based Policing feature, Cisco Express Forwarding must be configured on both the interface receiving the packet and the interface sending the packet.
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On a Cisco NCS 520 router, Class-Based Policing cannot be applied to packets that originated from or are destined to a device.
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Class-Based Policing can be configured on an interface or a subinterface.
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Class-Based Policing can be applied on physical interface or service instance.