Reference Guide

Configuring QoS is a three-step process:
1. Create class-maps to classify the traffic flows. The following are the different types of class-maps:
● qos (default)—Classifies the ingress data traffic.
● queuing —Classifies the egress queues.
● control-plane—Classifies the control-plane traffic.
● network-qos—Classifies the set of traffic-class IDs for ingress buffer configurations.
● application —Classifies the application type traffic. The reserved policy-map policy-iscsi defines the actions to be
performed for class-iscsi traffic.
2. Create policy-maps to define the policies for the classified traffic flows. The following are the different types of policy-maps:
● qos (default)—Defines the following actions on the traffic classified based on qos class-map.
○ Policing
○ Marking with a traffic class ID
○ Modifying packet fields such as CoS and DSCP
○ Enabling trust based classification
● queuing —Defines the following actions on the egress queues classified based on queuing class-map.
○ Shaping
○ Bandwidth assignment for queues
○ Strict priority assignment for queues
○ Buffer configuration for queues
○ WRED configuration on queues
● control-plane—Defines the policing of control queues for rate-limiting the control-plane traffic on CPU queues.
● network-qos—Defines the Ingress buffer configuration for selected traffic-classes matched based on network-qos
class-map.
● application —Defines the following actions for the application classified traffic.
○ Modify packet fields like CoS and DSCP.
○ Mark with a traffic class ID.
3. Apply the policy-maps to interface (port), system (all interfaces), or control-plane traffic as follows:
● Control-plane polices must be applied on control-plane mode.
● The qos and network-qos policies must be applied in the input direction on physical interfaces or on system-qos mode.
● Queuing policies must be applied in the output direction on physical interfaces or on system-qos mode.
● Application type policy-map must be applied on system-qos mode.
When a policy is applied on system, the policy is effective on all the ports in the system. However, interface level policy gets
precedence over system level policy.
Quality of service
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