Users Guide

2. Create policy-maps to define the policies for the classified traffic flows. The following are the different types of policy-maps:
● qos (default)—Defines the following actions on the traffic classified based on qos class-map:
○ Policing
○ Marking with a traffic class ID
○ Modifying packet fields such as CoS and DSCP
● queuing —Defines the following actions on the egress queues classified based on queuing class-map:
○ Shaping
○ Assigning bandwidth for queues
○ Assigning strict priority for queues
○ Buffering configuration for queues
○
Weighted random early detection (WRED)/Explicit congestion notification (ECN) configuration on queues
● control-plane—Defines the policing of control queues for rate-limiting the control-plane traffic on CPU queues.
● network-qos—Defines the Ingress buffer configuration for selected traffic-classes matched based on network-qos
class-map.
● application —Defines the following actions for the application classified traffic:
○ Modifying packet fields such as CoS and DSCP.
○ Marking traffic class IDs.
3. Apply the policy-maps to the port interface, system for all interfaces, or control-plane traffic as follows:
● Apply control-plane polices in Control-Plane mode.
● Apply QoS and network-QoS policies in the input direction on physical interfaces or in System-QoS mode.
● Apply queuing policies in the output direction on physical interfaces or in System-QoS mode.
● Apply an application type policy-map in System-QoS mode.
When you apply a policy at the system level (System-QoS mode), the policy is effective on all the ports in the system.
However, the interface-level policy takes precedence over the system-level policy.
Example 1: Traffic classification and bandwidth
allocation in VXLAN topology using CoS value
This example describes how to configure QoS in a VXLAN topology using the Class of Service (CoS) values.
In this example:
● The interfaces between the leaf switches and the hosts are VLAN-tagged interfaces.
● The interfaces between the leaf switches and the spine nodes are VLAN-tagged interfaces.
● VLAN-tagged interfaces use the CoS value to classify the traffic, allocate appropriate egress queue, and bandwidth. In this
example, traffic with a CoS value of 3 is assigned to queue 3.
● Trust dot1p configuration is used on leaf and spine switches. This configuration maps dot1p priority (CoS) value of 3 to
queue 3. OS10 by default maps all other traffic to queue 0.
● Queue 3 is allocated 65% bandwidth. Traffic with CoS value of 3 gets 65% bandwidth. If there is congestion at the egress
port, this traffic gets additional bandwidth thus avoiding traffic loss. Traffic with other CoS values gets the remaining
bandwidth per the default settings.
● The trust dot1p and queuing configurations are applied at the system-qos level to simplify the configuration and also to apply
the QoS configurations globally.
Quality of service
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