Request for Documentation on Configuring GRE Multicast Traffic with FortiGate Firewalls

Dear Team,

We have been exploring a solution to enable GRE multicast traffic to flow simultaneously to two FortiGate firewalls. After discussing with our team and consulting AWS Support, it has been confirmed that this configuration is feasible and supported on AWS infrastructure. AWS has assured us that there are no blockers on their side that would cause traffic disruption when sending GRE multicast traffic to both firewalls simultaneously.

However, as we are not using AWS VPN services, AWS was unable to provide any documentation specific to FortiGate configurations for this use case. Therefore, we would greatly appreciate your guidance on configuring FortiGate firewalls to handle GRE multicast traffic in this scenario. Specifically, if you have any documentation, best practices, or technical configurations for setting up such a system, please share them with us. Looking forward to your assistance. Regards,

Tanish Jain