Configuring Queuing And Scheduling - Cisco Nexus 9000 Series Configuration Manual

Configuring Queuing and Scheduling

• When downgrading to an earlier release of Cisco NX-OS, all ingress queuing configurations have to be
• The ingress queuing feature is supported only on platforms where priority flow control is supported.
• Ingress queuing is not supported on devices with 100G ports.
• The ingress queuing policy is supported only at the system level (and not at the interface level) for Cisco
• Beginning with Cisco NX-OS Release 7.0(3)F1(1), the Cisco Nexus 9636C-R and 9636Q-R line cards
Configuring Queuing and Scheduling
Queuing and scheduling are configured by creating policy maps of type queuing that you apply to an egress
interface. You cannot modify system-defined class maps, which are used in policy maps to define the classes
of traffic to which you want to apply policies.
System-defined class maps match based on QoS groups that can be customized using a type qos policy. By
default, there is no type QoS policy and all traffic matches to qos-group 0. One consequence is that all traffic
will hit the system-defined default-class of type network-qos and type queuing (assigns 100% bandwidth to
qos-group 0). Since system-defined classes of type queuing and type network-qos are predefined to match
based on distinct qos-groups and cannot be modified, the way to ensure that traffic hits a given type
queuing/network-qos class is to configure a type qos policy that sets the corresponding qos-group for that
traffic. For traffic classified into a system-defined class map matching on a qos-group other than 0, create a
type QoS policy that sets the QoS groups. Once the traffic has been mapped, it will be subject to the default
type network-qos and type queuing policies that operate on the non-default qos-group X (X !=0). You may
need to further customize those type queuing and type network-qos policies in order to ensure the desired
actions (e.g. re-allocate some bandwidth). For more information on setting the qos-group, see "Example of
set qos-groups" in the Using Modular QoS CLI chapter.
For information about configuring policy maps and class maps, see the Using Modular QoS CLI chapter.
You can configure the congestion-avoidance features, which include tail drop and WRED, in any queue.
You can configure one of the egress congestion management features, such as priority, traffic shaping, and
bandwidth in output queues.
Note WRED is not supported on ALE enabled device front panel 40G uplink ports. When WRED is configured
for the system level, the setting is ignored and no error message is displayed. When WRED is configured at
the port level, the setting is rejected and an error message displays.
The system-defined policy map, default-out-policy, is attached to all ports to which you do not apply a queuing
policy map. The default policy maps cannot be configured.
removed.
Nexus 9508 switches with the Cisco Nexus 9732C-EX line card and Cisco Nexus 93108TC-EX and
93180YC-EX switches.
and the Cisco Nexus 9508-FM-R fabric module (in a Cisco Nexus 9508 switch) support ingress queuing.
Cisco Nexus 9000 Series NX-OS Quality of Service Configuration Guide, Release 7.x
Configuring Queuing and Scheduling
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