Introduction to Adaptive Qos in Cisco SDWAN

Introduction to Adaptive Qos in Cisco SDWAN

Adaptive QoS is a feature that automatically adjusts the quality of service (QoS) settings on a network device based on available bandwidth and packet loss on the WAN link. 

This helps to maximize the performance and dependability of network traffic, especially for applications that are sensitive to delays or drops, such as voice or video.

As per the new changes from Cisco, Below are the new names of the components

  • Cisco vManage is now Cisco Catalyst SD-WAN Manager
  • Cisco vBond is now Cisco Catalyst SD-WAN Validator
  • Cisco vSmart is now Cisco Catalyst SD-WAN Controller

 Adaptive QOS in Cisco SDWAN

Adaptive QoS allows enterprise edge shapers (WAN interface shaper and per-tunnel shaper) to adapt to available WAN bandwidth, including Internet and Long-term Evolution (LTE). Thus, adaptive QoS may manage differential drops at the enterprise edge while reducing packet losses in the Internet core. 

Adaptive Qos in Cisco SDWAN
Fig 1.1- Adaptive Qos in Cisco SDWAN

When adaptive QoS is not available, shapers used in the egress QoS policy have static values. They are configured depending on the service provider's bandwidth offering and do not change over time, thus they do not represent the actual available Internet bandwidth.

 Benefits of Adaptive QOS

  • Controls the shaper parameters based on the real available Internet bandwidth in both directions, which is estimated at regular intervals
  • Enables you to configure a QoS policy on the spoke towards the hub
  • Improves application performance at the corporate edge, even when bandwidth fluctuates.
  • Adapts aggregate tunnel geometry to offer effective bandwidth between spokes and hubs.

 How Adaptive QoS works in Cisco SDWAN ?

Whenever the WAN link has a high packet loss, Adaptive QoS lowers the QoS shaper rate to minimize congestion and enhance traffic quality. On the other side, if the WAN link has enough bandwidth and minimal packet loss, Adaptive QoS will increase the QoS shaper rate to use the available resources and enhance the traffic throughput.

When bandwidth is limited, application traffic is more likely to experience packet drops at the Internet core, and the traffic cannot be distinguished by user-defined priority. In such cases, Cisco Catalyst SD-WAN adaptive QoS adjusts the shaper rate in real time based on Internet and LTE link capacity.

Cisco Catalyst SD-WAN Manager can implement adaptive QoS on a specific interface of an edge device deployed as a spoke in a hub-to-spoke network topology. You can set the minimum, maximum, and default values. You can also set a global timer interval on a WAN interface to measure drop rates.

If you want to configure it via CLI, the adaptive-qos command allows you to configure adaptive QoS on Cisco Catalyst SD-WAN devices. You can also select the WAN and local network loss thresholds, as well as the minimum and maximum QoS shaper rates for each application type.

 Configure Adaptive QoS from vManage 

Step 1: From the Cisco Catalyst SD-WAN Manager menu, choose Configuration > Templates.

Step 2: Click Feature Templates and then click Add Template.

Step 3: Choose a device from the list on the left (such as Cisco ISR8300). Feature templates that are applicable to the device are shown in the right pane.

Step 4: Choose one of the available Cisco VPN Interface templates. In this example, we've chosen the Cisco VPN Interface Ethernet template. Now Click ACL/QoS.

Step 5: Note that Adaptive QoS is deactivated by default. To enable it, select Global from the Adaptive QoS drop-down list and then Turn On and Save