ASYNCHRONOUS TRANSFER MODE SWITCH

摘要

An asynchronous transfer mode (ATM) switch (20) has plural switch ports (24) connected by respective bidirectional links (27, 28) to a switch core (22). Connected to each switch port is a corresponding row column unit (40), each row column unit managing the writing of service cells to one row of cross point units (32) and the reading of service cells from one column of cross point units. The bidirectional links between each switch port and its corresponding row column unit of the switch core carry both service cells and control cells. An interactive exchange of control cells is implemented to sequence operation of the switch core. The operations particularly dependent upon control cell generation include transmission of service cells from the switch core; transmission of pollstate control cells from the switch core; retrieval of contents of certain control registers maintained by the switch core; and synchronization procedures. Pollstate information, indicative of "occupied"/"free" status of selected ones of the cross point units, is transmitted in pollstate control cells. The pollstate control cells are generated and transmitted either (1) in response to a particular control cell evocative of the pollstate information, or (2) upon a change of absence/presence (e.g., free/occupied status) of a predetermined number of the affected cross point units.