Nexus 9k - Default QoS clarification

[Justin94]

Hello,

I've been trying to dig through posts, Cisco's 9k QoS documentation, etc but cannot find much on the default Qos behavior referenced in the Cisco 9k Quality of Service guide, quoted below.

I've come into an organization recently that has purchased two Nexus 9504's, which to start are far, far more powerful than we will ever utilize. The only QoS marked traffic we currently have is our Cisco VOIP system. I'm trying to determine two things:

1. A way to see what the default policy does in terms of prioritization/bandwidth allocation for different dscp classes.

2. Confirm the default policy is applied/on. It looks like I can also do "service-policy type network-qos default-nq-policy"

It's just figuring out what falls under the "default-nq-policy" that I'm struggling with. I think we'll be fine with that, we're a relatively small organization but I want to at least confirm it will treat our EF traffic properly. Any thoughts are appreciated!

Quote from the Cisco Nexus 9000 Series NX-OS Quality of Service Configuration Guide, Release 10.3(x):

Default QoS Behavior

The QoS queuing features are enabled by default. Specific QoS-type features, such as policing and marking, are enabled only when a policy is attached to an interface. Specific policies are enabled when that policy is attached to an interface.

By default, the device always enables a system default queuing policy, or system-defined queuing policy map, on each port and port channel. When you configure a queuing policy and apply the new queuing policy to specified interfaces, the new queuing policy replaces the default queuing policy, and those rules now apply.

The device enables other QoS features, policing and marking, only when you apply a policy map to an interface.

[Joseph W. Doherty]

What's shown using the following commands?

Verifying the Network QoS

To display the policing configuration information, perform one of the following tasks:

Command	Purpose
show class-map type network-qos	Displays the type network-qos class maps.
show policy-map type network-qos	Displays the type network-qos policy maps.
show policy-map system type network-qos	Displays the active type network-qos class maps.

[Justin94]

Hello,

Nexus-9504-01# show class-map type network-qos

Type network-qos class-maps
===========================
class-map type network-qos match-any c-nq1
Description: Default class on qos-group 1
match qos-group 1
class-map type network-qos match-any c-nq2
Description: Default class on qos-group 2
match qos-group 2
class-map type network-qos match-any c-nq3
Description: Default class on qos-group 3
match qos-group 3
class-map type network-qos match-any c-8q-nq1
Description: Default class on qos-group 1
match qos-group 1
class-map type network-qos match-any c-8q-nq2
Description: Default class on qos-group 2
match qos-group 2
class-map type network-qos match-any c-8q-nq3
Description: Default class on qos-group 3
match qos-group 3
class-map type network-qos match-any c-8q-nq4
Description: Default class on qos-group 4
match qos-group 4
class-map type network-qos match-any c-8q-nq5
Description: Default class on qos-group 5
match qos-group 5
class-map type network-qos match-any c-8q-nq6
Description: Default class on qos-group 6
match qos-group 6
class-map type network-qos match-any c-8q-nq7
Description: Default class on qos-group 7
match qos-group 7
class-map type network-qos match-any c-nq-default
Description: Default class on qos-group 0
match qos-group 0
class-map type network-qos match-any c-8q-nq-default
Description: Default class on qos-group 0
match qos-group 0

Nexus-9504-01# show policy-map type network-qos

Type network-qos policy-maps
============================
policy-map type network-qos default-nq-policy
class type network-qos c-nq3
match qos-group 3
mtu 1500
class type network-qos c-nq2
match qos-group 2
mtu 1500
class type network-qos c-nq1
match qos-group 1
mtu 1500
class type network-qos c-nq-default
match qos-group 0
mtu 1500
policy-map type network-qos default-8q-nq-policy
class type network-qos c-8q-nq7
match qos-group 7
mtu 1500
class type network-qos c-8q-nq6
match qos-group 6
mtu 1500
class type network-qos c-8q-nq5
match qos-group 5
mtu 1500
class type network-qos c-8q-nq4
match qos-group 4
mtu 1500
class type network-qos c-8q-nq3
match qos-group 3
mtu 1500
class type network-qos c-8q-nq2
match qos-group 2
mtu 1500
class type network-qos c-8q-nq1
match qos-group 1
mtu 1500
class type network-qos c-8q-nq-default
match qos-group 0
mtu 1500

Nexus-9504-01# show policy-map system type network-qos

Type network-qos policy-maps
============================
policy-map type network-qos default-nq-policy
class type network-qos c-nq3
match qos-group 3
mtu 1500
class type network-qos c-nq2
match qos-group 2
mtu 1500
class type network-qos c-nq1
match qos-group 1
mtu 1500
class type network-qos c-nq-default
match qos-group 0
mtu 1500

[Joseph W. Doherty · Accepted solution]

If I'm reading/understanding the output from those show commands, all is default QoS, with the 4Q policy being the active default.

What I don't see is what's being placed into the QoS groups  (I've seldom worked with Nexus platforms beyond using internal company standard templates for configs - I would need to study Nexus QoS documentation to see how traffic maps into QoS groups).  Possibly all traffic is being defaulted into just one qos-group, group zero.

[Justin94]

I think you're correct. I can't immediately recall which command I ended up coming across yesterday, but it showed 4 groups and group 0 had the text, "bandwidth 100% remaining" and the others had 0. Thinking I will need to create at least a basic QoS policy. 

Thank you for your insight.