Communication control system

摘要

The communication control system of the present invention includes a cell buffer assembly that is common to a plurality of input ports and stores cells. A writing controller and a reading controller respectively control a process of writing a cell into the cell buffer assembly and a process of reading a cell from the cell buffer assembly. A writing time management memory maps a writing time of each cell to each area in the cell buffer assembly and manages the mapping. A cell discard controller discards a cell having a long elapsed time since the writing time stored in the writing time management memory by the processing, which is independent of the processing by the writing controller and the reading controller. The arrangement of discarding the oldest cell independently of the writing and reading operations enables efficient discard of cells, while ensuring a desired communication rate. This arrangement simplifies the cell discard control and enhances its efficiency in the case of convergence in multiplex communication in the form of fixed-length cells.