In Traditional WAN networks, routers make forwarding decisions based primarily on link-state and routing metrics. Cisco SD-WAN allows us to configure SLA-based routing that considers performance characteristics such as packet loss, latency, and jitter when making forwarding decisions.
An Application-Aware Routing (App-route) policy allows the SD-WAN fabric to monitor the quality of network paths in real-time and do SLA-driven routing across the best available transports. App-route policies rely on BFD to detect performance issues such as packet loss, latency, and jitter on the overlay tunnels. Suppose BFD reports that IPsec tunnel characteristics have become worse than the defined SLA class for a given application. In that case, the App-route policy automatically moves the matched application traffic off the network path, experiencing performance degradation. The app-route policy automatically returns the application traffic as the network eventually recovers from the brownout condition. Figure 1 shows where an App-route policy fits into the Cisco SD-WAN policy framework.
The Application-Aware routing policies allow WAN Edge routers to consider the performance characteristics of the available overlay tunnels when making network path decisions for given application traffic.
