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30-13
Cisco ME 3400 Ethernet Access Switch Software Configuration Guide
78-17058-01
Chapter 30 Configuring QoS
Understanding QoS
These sections describe the types of policing supported on the switch:
• Individual Policing, page 30-13
• Aggregate Policing, page 30-14
• Unconditional Priority Policing, page 30-15
Individual Policing
Individual policing applies only to input policy maps. In policy-map configuration mode, you enter the
class command followed by class-map name, and enter policy-map class configuration mode.
Note Individual policing is not supported for the class class-default.
You use the police policy-map class configuration command to define the policer, the committed rate
limitations of the traffic, committed burst size limitations of the traffic, and the action to take for traffic
that is below the limits (conform-action) and above the limits (exceed-action). If you do not specify
burst size (bc), the system calculates an appropriate burst size value. The calculated value is appropriate
for most applications. For more information, see the “Attaching a Traffic Policy to an Interface” section
on page 30-35.
To make the policy map effective, you attach it to a physical port by using the service-policy input
interface configuration command. Policing is done only on received traffic, so you can only attach a
policer to an input service policy.
This is an example of basic policing for all traffic received with a CoS of 4. The first value following the
police command limits the average traffic rate to 10, 000,000 bits per second (bps); the second value
represents the additional burst size (10 kilobytes). The policy is assigned to Fast Ethernet port 1.
Switch(config)# class-map video-class
Switch(config-cmap)# match cos 4
Switch(config-cmap)# exit
Switch(config)# policy-map video-policy
Switch(config-pmap)# class video-class
Switch(config-pmap-c)# police 10000000 10000
Switch(config-pmap-c-police)# exit
Switch(config-pmap-c)# exit
Switch(config-pmap)# exit
Switch(config)# interface fastethernet0/1
Switch(config-if)# service-policy input video-policy
Switch(config-if)# exit
You can use the conform-action and exceed-action policy-map class configuration commands or the
conform-action and exceed-action policy-map class police configuration commands to specify the
action to be taken when the packet conforms to or exceeds the specified traffic rate.
Note You cannot configure marking simultaneously in both conform-action and exceed-action for the same
policer instance.
Conform actions are to send the packet without modifications, to set a QoS group value for classification
at the egress, or to set a new CoS, DSCP, or IP precedence value. Exceed actions are to drop the packet
or to set a new CoS, DSCP, or IP precedence to a value defined in a table map and then send the packet.
Table maps list specific traffic attributes and map (or convert) them to other attributes.