Instead of depending on the SASE Orchestrator to determine route choice, the Distributed Cost Calculation (DCC) functionality makes use of the SD-WAN Edges and Gateways to perform the calculation. Following the completion of the learning process, the Edge and Gateway each immediately insert the routes, and they then communicate these preferences to the Orchestrator.
DCC solves a problem that arises in large-scale deployments is that relying solely on the Orchestrator can prevent timely route preference updates. This can occur for a number of reasons, including the fact that the Orchestrator may not be able to be reached by an Edge or Gateway in order to receive updated routing preferences, or that the Orchestrator may be unable to deliver route updates quickly when it is calculating a large number of them all at once. It is possible to ensure that route updates are both quick and reliable by delegating the responsibility for route preference calculation to the Edges and Gateways.
Below table describes the different kinds of dynamic routes that SD-WAN can handle, and a table below it provides a list of all the different kinds of routes. First, a dynamic route is put into a group based on whether it was learned at the Edge or the Gateway.
