A switch, switched architecture and process for transferring data through
an FCAL switch is disclosed. The switch uses multiple switch control
circuits each coupled to one FCAL network and all connected to a crossbar
switch. The switch control circuits are coupled together by a protocol
bus for coordination purposes. Local conversations can occur on each FCAL
loop and crossing conversations through the switch can occur
concurrently. The OPN primitive is used to establish the connection
before any data is transferred thereby eliminating the need for buffer
memory in the switch control circuits. The destination address of each
OPN is used to address a lookup table in each switch control circuit to
determine if the destination node is local. If not, the destination is
looked up and a connection request made on the protocol bus. If the
remote port is not busy, it sends a reply which causes both ports to
establish a data path through the backplane crossbar switch.