Self-healing and application protection
In order to remediate network connectivity problems, SD-WAN proactively measures network conditions such as latency, jitter, and packet loss on WAN links and use these metrics to adjust traffic according to the application service-level agreements (SLAs). This is often referred to as SLA-based path steering and is discussed in SD-WAN rules.
In the same way that applications are evaluated against their specific SLAs, SD-WAN overlay members can be evaluated to determine whether they are healthy or not using SLAs of their own. This enables the SD-WAN to leverage BGP to signal to other nodes in the SD-WAN network that one or more of their members is unhealthy, or out-of-SLA. The nodes can then use this SLA status to prioritize IKE and BGP routes, favoring those that meet performance thresholds (within SLA). This real-time health signaling across nodes improves link visibility, which is especially critical in hub-and-spoke topologies with many connections. By offloading the SLA reporting task to spokes, the processing load on hubs is reduced, allowing for increased efficiency and scaling.
In some situations, there may be no healthy (or in-SLA) links for SD-WAN to direct traffic over. In this case, FortiGate has advanced techniques, such as forward error correction (FEC) and packet duplication, to boost resilience when multiple paths fail. This preserves the user experience and provides business continuity when there would be an outage otherwise.
This section contains the following topics: