Cisco Nexus 9000 Series Configuration Manual page 22

Using QoS
• Queuing policies use the queuing and scheduling features.
Note The system-defined QoS features and values that are discussed in the "Using Modular QoS CLI" section apply
globally to the entire device and cannot be modified.
Using QoS
Traffic is processed based on how you classify it and the policies that you create and apply to traffic classes.
To configure QoS features, you use the following steps:
1. Create traffic classes by classifying the incoming packets that match criteria such as IP address or QoS
fields.
2. Create policies by specifying actions to take on the traffic classes, such as policing, marking, or dropping
packets.
3. Apply policies to a port, port channel, or subinterface.
You use MQC to create the traffic classes and policies of the QoS features.
Note The queuing and scheduling operations of the overall QoS feature are applicable to both IPv4 and IPv6.
Note IP tunnels do not support access control lists (ACLs) or QoS policies.
Classification
You use classification to partition traffic into classes. You classify the traffic based on the port characteristics
or the packet header fields that include IP precedence, differentiated services code point (DSCP), Layer 3 to
Layer 4 parameters, and the packet length.
The values used to classify traffic are called match criteria. When you define a traffic class, you can specify
multiple match criteria, you can choose to not match on a particular criterion, or you can determine the traffic
class by matching any or all criteria.
Traffic that fails to match any class is assigned to a default class of traffic called class-default.
Marking
Marking is the setting of QoS information that is related to a packet. You can set the value of a standard QoS
field for COS, IP precedence and DSCP, and internal labels (such as QoS groups) that can be used in subsequent
actions. Marking QoS groups is used to identify the traffic type for queuing and scheduling traffic.
Cisco Nexus 9000 Series NX-OS Quality of Service Configuration Guide, Release 7.x
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Overview