Load balancing : Load balancing among links : Link load balancing for outbound traffic : Monitoring link health or availability
Monitoring link health or availability
If you want FortiADC to avoid links that are not available, or links that do not have complete routes to crucial IP addresses, configure link health checks. Each link health check will periodically send an ICMP ECHO probe (ping) from the IP of a virtual server or interface IP to a beacon — an IP address that must be reachable in order for the link to be deemed available. A beacon can be any IP address, such as a main office, core router, or virtual server at another data center.
You do not necessarily need to configure the source address of the health check or its individual probes unless you want it to differ from the network interface’s IP, or differ from the source IP used by other probes in the health check. The probe’s source IP address is configurable at multiple levels. FortiADC will use most specific source address that you configure for each probe.
If Source IP is configured for that specific probe in the health check’s Members table, FortiADC will use that source address as the SRC field in the packet’s IP header.
If a probe’s Source IP remains at its default value ( but you have configured an overall Source Address that can be used by all probes in the health check, FortiADC will use that source address.
If both Source Address and Source IP settings are not configured (remaining at their default value of, FortiADC will use the IP address of the network interface where the packet is egressing.
To configure link health checks, go to Link Load Balance > Outbound > Health Check.