Understanding the switch mechanism and how links are chosen

When each metric is measured or calculated, a score is calculated for every link: this involves comparing the last measurement (latency) or last metric calculation (jitter or packet loss rate) with the value set in the SD-WAN SLA.
The link that obtains the best score is chosen to transport traffic.

In a four-link configuration (two main links and two backup links), the table below shows how the links will be chosen based on their respective status at a given moment, and based on the chosen configuration (whether there is load balancing, threshold values, etc.):

 

Legend

		Optimal link
		Degraded link (does not meet SLA thresholds)
		Highly degraded link (when several links are degraded : link with the lowest score)
		Link not available