Cisco Systems A9014CFD manual Input and Output Policies, Input Policy Maps, 24-5

Chapter 24 Configuring QoS

Understanding QoS

Step 3 Attach the traffic policy to an interface.

Use the service-policyinterface configuration command to attach the policy map to an interface for packets entering or leaving the interface. You must specify whether the traffic policy characteristics should be applied to incoming or outgoing packets. For example, entering the service-policy output class1 interface configuration command attaches all the characteristics of the traffic policy named class1 to the specified interface. All packets leaving the specified interface are evaluated according to the criteria specified in the traffic policy named class1.

Note If you enter the no policy-map configuration command or the no policy-mappolicy-map-nameglobal configuration command to delete a policy map that is attached to an interface, a warning message appears that lists any interfaces from which the policy map is being detached. For example:

Warning: Detaching Policy test1 from Interface GigabitEthernet0/1

The policy map is then detached and deleted.

Input and Output Policies

Policy maps are either input policy maps or output policy maps, attached to packets as they enter or leave the router by service policies applied to interfaces. Input policy maps perform policing and marking on received traffic. Policed packets can be dropped or reduced in priority (marked down) if they exceed the maximum permitted rates. Output policy maps perform scheduling and queuing on traffic as it leaves the router.

Input policies and output policies have the same basic structure; the difference is in the characteristics that they regulate. Figure 24-2shows the relationship of input and output policies.

You can configure a maximum of 32 policy maps.

You can apply one input policy map and one output policy map to an interface.

Figure 24-2

Apply input policy

Apply output policy

Input and Output Policy Relationship

Ingress	Switching
port	and
	forwarding

Egress

port

Apply output policy

Apply input policy

141150

Input Policy Maps

Input policy map classification criteria include matching a CoS, a DSCP, or an IP precedence value or VLAN ID (for per-port, per-VLAN QoS). Input policy maps can have any of these actions:

•Setting or marking a CoS, a DSCP, an IP precedence, or QoS group value

•Individual policing

•Aggregate policing

	Cisco ASR 901 Series Aggregation Services Router Software Configuration Guide
OL-23826-09		24-5