Method and apparatus for relative rate marking switches

A data transfer flow control system includes a plurality of nodes or switches in a network, which are interconnected by transmission links. Resource management cells are transmitted along with data cells in information transfer sessions. As the amount of session traffic at any node increases, the level of occupancy of the buffers for that node correspondingly increases to temporarily store overflow data. At every network node, a "fair share" cell rate is determined for each output transmission link. Whenever the current cell rate (CCR) of any session exceeds the fair share cell rate for the output link at a node, the buffer occupancy threshold values for setting congestion indication fields in the resource management cells are adjusted downwardly such that a lower threshold buffer occupancy will effect a traffic congestion setting for that session.