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Configuring QoS
Understanding QoS
To configure multiple actions in a class, you can enter multiple conform or exceed action entries conform, exceed, or
violate action entries in policy-map class police configuration mode, as in this example:
Switch(config)# policy-map map1
Switch(config-pmap)# class class1
Switch(config-pmap-c)# police 100000 500000
Switch(config-pmap-c-police)# conform-action set-cos-transmit 4
Switch(config-pmap-c-police)# conform-action set-dscp-transmit dscp table conform-dscp-to-dscp-mutation
Switch(config-pmap-c-police)# conform-action set-qos-transmit 10
Switch(config-pmap-c-police)# exceed-action set-cos-transmit 2
Switch(config-pmap-c-police)# exceed-action set-dscp-transmit dscp table exceed-dscp-to-dscp-mutation
Switch(config-pmap-c-police)# exceed-action set-qos-transmit 20
Switch(config-pmap-c-police)# exit
Switch(config-pmap-c)# exit
Switch(config-pmap)# exit
Aggregate Policing
Aggregate policing applies only to input policy maps. An aggregate policer differs from an individual policer because it
is shared by multiple traffic classes within a policy map. Cisco Industrial Ethernet Switches support 1-rate, 2-color
ingress policing and 2-rate, 3-color policing for aggregate policing.
You can use the policer aggregate global configuration command to set a policer for all traffic received or sent on a
physical interface. When you configure an aggregate policer, you can configure specific burst sizes and conform and
exceed actions. If you do not specify burst size (bc), the system calculates an appropriate burst size value. The calculated
value is appropriate for most applications.
When you configure a 2-rate policer, in addition to configuring the committed information rate (CIR) for updating the first
token bucket, you also configure the peak information rate (PIR) at which the second token bucket is updated. If you do
not configure a PIR, the policer is a standard 1-rate, 2-color policer.
For 2-rate, 3-color policing, you can then optionally set actions to perform on packets that conform to the specified CIR
and PIR (conform-action), packets that conform to the PIR, but not the CIR (exceed-action), and packets that exceed the
PIR value (violate-action).
Note:
If the conform action is set to drop, the exceed and violate actions are automatically set to drop. If the exceed
action is set to drop, the violate action is automatically set to drop.
If you set the CIR value equal to the PIR, a traffic rate that is less than or equal to the CIR is in the conform range.
Traffic that exceeds the CIR is in the violate range.
If you set the PIR greater than the CIR, a traffic rate less than the CIR is in the conform range. A traffic rate that
exceeds the CIR but is less than or equal to the PIR is in the exceed range. A traffic rate that exceeds the PIR is in
the violate range.
If you do not configure PIR, the policer is configured as a 1-rate, 2-color policer.
Setting the burst sizes too low can result in less traffic than expected. Setting burst sizes too high can result in more
traffic than expected.
You can configure multiple conform and exceed actions simultaneously for each service class. 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, to send the packet without modification, to set a
QoS group for classification at the egress, or to set a new CoS, DSCP, or IP precedence to a value. You can configure
each marking conform or exceed action by using explicit values, using table maps, or using a combination of both. Table
maps list specific traffic attributes and map (or convert) them to other attributes.
You can configure multiple conform, exceed, and violate actions simultaneously for each service class. You can use the
conform-action, exceed-action, and violate-action policy-map class configuration commands or the
conform-action, exceed-action, and violate-action policy-map class police configuration commands to specify the
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