Hi,
As a matter of thumb, technologies based on virtual circuits are usually NBMA. This covers Frame Relay and ATM, for example. Technologies like Ethernet or WiFi are BMA.
More fundamentally, if the link layer technology is capable of replicating broadcasts and multicasts on its own, it is a broadcast multiaccess technology. A node connected to a BMA network sends a single broadcast frame, and the link layer technology itself makes sure the frame gets delivered to all other stations in the broadcast domain.
If, however, the network has no mechanism to replicate broadcast and multicasts, it is an NBMA. A sending node attached to an NBMA network must create as many copies of the broadcast frame as many neighbors it has, and it must send a copy of each broadcast frame to every node.
Best regards,
Peter
