ATM network congestion control system using explicit rate cell marking

An explicit rate algorithm is disclosed for use in an end-to-end closed loop flow control algorithm for an ATM network which carries at least constant bit rate (CBR) traffic, variable bit rate (VBR) traffic and adjustable bit rate (ABR) traffic. The algorithm determines how much additional bandwidth is available for ABR traffic on an output link from a node and produces an explicit rate variable that can be forwarded to a source for the ABR traffic. Both the maximum and minimum bandwidths already reserved for all connections on the output link are determined. A single reserved bandwidth value is chosen within the range defined by the maximum and minimum reserved bandwidth values. The current utilization of the ABR input buffer for the node is also determined. The explicit rate variable is generated as a function of the link capacity, the reserved bandwidth value and the current utilization of the ABR input buffer. The explicit rate variable is written into a resource management cell which is routed through the network to the ABR traffic source. The explicit rate variable is intended to change the input rate of the ABR source to utilize more of the ABR input buffer.