Start Bit

Sender: Just set dominant to data bus.

Receiver: Start data read procedure.  Synchronize clock if necessary.

Wire ID

Sender: Send Wire ID.  Read every bit from the bus.  If one or more bits are different from sent one, this sender would back off.

Receiver: Read the wire ID from the bus.

Back Off Policy

If sender finds no conflict in the wire ID transfer, the sender proceeds to continue bit.  If the sender finds conflict, sender back off.

Receiver stops reading if continue bit is recessive.  Next coming dominant bit should be start bit for another frame.