Polling-based apparatus and system guaranteeing quality of service

A polling-based communication apparatus and system. The apparatus of the invention, connected to a host computer through a peripheral bus, comprises an arbiter and multiple addressable entities. Each addressable entity corresponds to one of queues maintained in the host computer. The arbiter can determine which queue is to be served next in accordance with a quality of serve policy. The host computer polls each addressable entity by issuing a query packet. Depending on the queue chosen to be served next, the arbiter grants the corresponding addressable entity access to the peripheral bus, causing this granted addressable entity to respond to the host computer's polling with an acknowledgement packet. Thus the host computer initiates transactions to transfer data packets from the chosen queue through the peripheral bus to the corresponding addressable entity.