QoS Configuration in NX-OS [MQC Explained and Configuration Example]

QoS Configuration in NX-OS [MQC Explained and Configuration Example]

Cisco Modular QoS CLI (MQC)

Cisco Modular Quality of Service Command Line Interface (MQC) provides a Standard CLI to define and configure QoS policies.

This diagram from CiscoLive illustrate what MQC is about:

The Qos configuration in Nexus 9000 can be achieved in 3 steps:

  1. Define traffic classes.
  2. Associate policies and actions with each traffic class.
  3. Attach policies to logical or physical interfaces.


Classification is the separation of packets into traffic classes. You configure the device to take a specific action on the specified classified traffic, such as policing or marking down, or other actions


We can use class-map mainly match and then classify traffic based on these parameters:

  • CoS
  • DSCP
  • IP Precedence
  • ACL

Configuration Examples:

  • Example1: Qos class-map:
    syntax: class-map type qos [match-any | match-allclass-name
    config example: class-map type qos MyClass
  • Example2: Queuing class-map
    syntax: class-map type qos [match-any | match-allclass-name
    Config example: class-map type queuing match-any c-out-q2


Configure a Policy-map to match on the Class-map and define actions to perform on them: such as marking with DSCP, Cos, setting Qos-class , setting bandwitch, Policing, etc.

Configuration Examples:

  • Example1: Qos Policy-map
    syntax: policy-map type qos { [match-firstpolicy-map-name}
    config example: policy-map type qos MyPolicy
  • Example2: Queuing policy-map
    syntax: policy-map type queuing [match-any | match-allclass-name
    Config example: policy-map type queuing MyPol_queue


To attach a policy map to an interface or VLAN, use the service-policy command. It will Apply the specified policy map to input or output packets on the interface.

Configuration Examples:

  • Example1: Apply Policy1 on interface 10
    Interface slot/port
    service-policy [type qos] {input | output} {policy-map-name} [no-stats]

Configuration Example

Let’s take first a simple example that will match on Cos 3 and set precedence 5 on the ingress interface Ethernet 1/5:

1- Class-map: Class1:

! create Policy-map Policy1
switch(config)# class-map Class1

! match on cos 3
switch(config-cmap-qos)# match cos 3

2- Policy-map: Policy1:

! create Policy-map Policy1
switch(config)# policy-map policy1

! match on class-map class1:
switch(config-pmap-qos)# class Class1

! setting precedence to 3:
switch(config-pmap-c-qos)# set precedence 3

3– Service-Policy:

interface ethernet 1/5
service-policy input Policy1


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