Summarized on September 30, 2026
Application-Aware Routing (AAR) tracks network and path characteristics of data plane tunnels between Cisco IOS XE Catalyst SD-WAN devices, using BFD-measured metrics — packet loss, latency, and jitter — to compute optimal paths for application traffic. [1] AAR policy is a type of centralized data policy configured on the Cisco SD-WAN Controller (vSmart), which then automatically pushes it to the appropriate edge devices; it affects only traffic flowing from the service (LAN) side to the tunnel (WAN) side of the device.
To define SLA classes, navigate in Cisco SD-WAN Manager to the policy configuration area and create a named SLA class list with the following parameters:
- Set the maximum Loss (0–100 percent)
- Set the maximum Latency (1–1,000 milliseconds)
- Set the maximum Jitter (1–1,000 milliseconds)
- Optionally assign an App Probe Class for per-class BFD probing with specific DSCP markings per tunnel color
- Optionally enable Fallback Best Tunnel with criteria such as latency, loss, or jitter to select the best available path when no tunnel meets the SLA
Once SLA classes are defined, traffic rules are configured by creating numbered match-action sequences within an Application-Aware Routing policy. Match conditions can include application or application family lists, source/destination prefixes, DSCP values, protocol numbers, and destination ports. The corresponding action directs matched traffic to a tunnel satisfying the specified SLA class, with options to set a preferred tunnel color, enforce strict dropping if no SLA-compliant tunnel exists, or fall back to the best available path. After configuring traffic rules, the policy is associated with site lists and VPN lists, then activated in Cisco SD-WAN Manager, which pushes it to all connected controllers and their associated edge devices.