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24-17
Cisco ASR 901 Series Aggregation Services Router Software Configuration Guide
OL-23826-09
Chapter 24 Configuring QoS
Understanding QoS
This example shows how to use the priority percent command to configure out-class1 as the priority
queue, with traffic going to the queue limited to 20,000,000 bps so that the priority queue never uses
more than that. Traffic above that rate is dropped. This allows other traffic queues to receive some port
bandwidth, in this case a minimum bandwidth guarantee of 50% and 20%. The class class-default queue
gets the remaining port bandwidth.
Router(config)# policy-map policy1
Router(config-pmap)# class out-class1
Router(config-pmap-c)# priority percent 20
Router(config-pmap-c)# exit
Router(config-pmap)# class out-class2
Router(config-pmap-c)# bandwidth percent 50
Router(config-pmap-c)# exit
Router(config-pmap)# class out-class3
Router(config-pmap-c)# bandwidth percent 20
Router(config-pmap-c)# exit
Router(config-pmap)# exit
Router(config)# interface gigabitethernet0/1
Router(config-if)# service-policy output policy1
Router(config-if)# exit
Egress Policing
Egress policing can be classified based on QoS-groups, DSCP, and precedence value. For QoS-groups
to work at egress, you should map the traffic at ingress to a specific QoS-group value.
Restrictions
• Egress policing is supported only on the physical interface (policy-maps are applied only at port
level).
• Egress policing on EVC is not supported.
• Egress policing supports up to 64 policers.
• Only byte counters are supported.
• Only drop and pass counters are supported.
• Policing and queuing are not supported together in a policy-map.
• Hierarchical egress policing is not supported.
Configuration Example
This is an example for egress policing on a physical interface:
class-map match-all dscp1
match ip dscp 1
class-map match-all Q1
match qos-group 1
policy-map ingress
class dscp1
set qos-group 1
policy-map egress
class Q1
police cir 5000000
int gig 0/1
service-policy input ingress
int gig 0/0
service-policy output egress
end