System Classes; Default System Classes; Using An Mqc Object - Cisco Nexus 9000 Series Configuration Manual

System Classes

Note The qos type is the default.
Egress QoS policies are not supported on the subinterfaces.
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.
Caution In the interface configuration mode, the device can accept QoS and access control list (ACL) commands
irrespective of the line card on which the interface host is up or down. However, you cannot enter the interface
submode when the line card is down because the device does not accept any preconfiguration 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.

Using an MQC Object

You configure QoS and queuing policies using the MQC class-map and policy-map objects. After you configure
class maps and policy maps, you can attach one policy map of each type to an interface. A QoS policy can
only be applied to the ingress direction.
Cisco Nexus 9000 Series NX-OS Quality of Service Configuration Guide, Release 7.x
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Using Modular QoS CLI