What is the correct Load Balancing Algorithm Weight when one of the SDWAN interfaces is down?

Hi Potato168,

You have given the total weight for 3 WAN interfaces as 50,50 and 11.

To correctly balance the volume load when one of the SD-WAN interfaces is down in Fortigate, you should adjust the weight of the available interface to 50-50. This ensures that all traffic is directed through the operational interface.

For volume based, the FortiGate distributes the work load based on the amount of packets going through the interfaces.

The FortiGate uses the volume weight that you assign to each interface to calculate a percentage of the total bandwidth that’s allowed to go through each interface. The FortiGate then distributes the bandwidth between the interfaces accordingly.

When SD-WAN load-balance mode is measured-volume-based. Both members are under volume and still have room:

diagnose sys sdwan member

https://community.fortinet.com/t5/FortiGate/Technical-Note-WAN-load-balance-volume-based-and-redundant/ta-p/196003
https://docs.fortinet.com/document/fortigate/7.4.0/administration-guide/818746/sd-wan-related-diagnose-commands

Regards,
Aman