System Classes; Default System Classes - Cisco Nexus 9000 Series Configuration Manual

System Classes

You define the following class-map and policy-map object types when you create them:
• network qos—Defines MQC objects that you can use for system level related actions.
• qos—Defines MQC objects that you can use for marking and policing.
• queuing—Defines MQC objects that you can use for queuing and scheduling.
The qos type is the default.
Note
Egress QoS policies are not supported on the sub-interfaces.
You can attach policies to ports, port channels, or subinterfaces by using the service-policy command.
You can view all or individual values for MQC objects by using the show class-map and show policy-map
commands.
In interface configuration mode, the device might accept QoS and access control list (ACL) commands
Caution
irrespective of the line card on which the interface host is up or down. However, you cannot enter interface
submode when the line card is down because the device does not accept any pre-configuration information.

System Classes

The system qos is a type of MQC target. You use a service policy to associate a policy map with the system
qos target. A system qos policy applies to all interfaces on the device unless a specific interface has an
overriding service-policy configuration. The system qos policies are used to define system classes, the classes
of traffic across the entire device, and their attributes.
If service policies are configured at the interface level, the interface-level policy always takes precedence
over the system class configuration or defaults.
When you configure QoS features, and the system requests MQC objects, you can use system-defined MQC
objects for 4q mode or system-defined objects for 8q mode.
On the Cisco Nexus device, a system class is uniquely identified by a qos-group value. A total of four system
classes are supported. The device supports one default class which is always present on the device. Up to
three additional system classes can be created by the administrator. Only egress queuing, network-qos, and
type qos for FEX policies are supported on the system QoS target.

Default System Classes

The device provides the following system classes:
• Drop system class
By default, the software classifies all unicast and multicast Ethernet traffic into the default drop system class.
This class is identified by qos-group 0.
Cisco Nexus 9000 Series NX-OS Quality of Service Configuration Guide, Release 7.x
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Using Modular QoS CLI