In a
broadband switching
system for the switching of asynchronously transferred cells of data, a dynamic bandwidth controller (
DBC) controls the application of data cells to an input port of the
system. Data cells are supplied by a number of transmitting end-systems. When an end-
system begins transmitting data cells, the
DBC detects the presence of incoming cells and requests bandwidth from a connection
admission control (CAC) forming part of the system. The switching system stores a table associating a number of
signal sources connected to the ingress with respective predetermined transmission bandwidths and, preferably also, maximum
delay times. When arrival of cells from one of the sources at the input port is detected, the
DBC sends a request
signal for the relevant predetermined bandwidth to the CAC and delays transmission of the cells until at least the predetermined bandwidth is allocated. This
delay is typically effected by sending a
cell rate indicator
signal back to the input port for placing the source in a halt mode. If no allocation of bandwidth has occurred before the respective maximum
delay time, bandwidth is allocated by
robbing bandwidth form other signal sources.