A real physical circuit, bypassing the public internet entirely.
Three virtual interface types ride on top of the same physical connection.
Private VIFInto a specific VPC via VGW/DXGW
Public VIFTo AWS public services over your private circuit
Transit VIFDirectly to a Transit Gateway
BFD detects failure in ~900ms (300ms interval × 3) vs. BGP's default 90-second hold timer — nearly 100x faster, and the actual reason a well-configured failover is invisible to users.