FortiGate Next Generation Firewall utilizes purpose-built security processors and threat intelligence security services from FortiGuard labs to deliver top-rated protection and high performance, including encrypted traffic.
Value BFD Diagnostic Code Name ----- ------------------------ 0 No Diagnostic 1 Control Detection Time Expired 2 Echo Function Failed 3 Neighbor Signaled Session Down 4 Forwarding Plane Reset 5 Path Down 6 Concatenated Path Down 7 Administratively Down 8 Reverse Concatenated Path Down 9-31 Unassigned For Fortinet, here is the define: 0x01: Local inactive timer expired. 0x03: Remote peer indicates it's down. 0x23: Remote peer indicates restarting.
So for BDF local_diag code 0x03 and 0x23, customer needs to investigate remote peers other than FGT.