A parallel computer system is disclosed comprising a plurality of high level processors joined together using a cross-point or cross-bar switch. The system includes an adapter between each processor and the switch. Protocol processing to drive the switch, transfer pages and schedule transmissions between the processor is performed by the adapter. The protocol use the notion of typed or tagged buffer management that allows a client to bind the semantics of a message being sent or received. These semantics specify behaviours in the protocol when message packets depart or when they arrive.