Abstract: A node for an access control system for a multi-channel data transmission ring is disclosed. Access to a channel is controlled exclusively by one node, which is the only data receiving node connected to that channel. The receiving node generates slots so that other connected nodes can transfer data to the receiving node. The receiving node can provide balanced access to the channel by all connected nodes. Further embodiments feature prevention of congestion in the buffer of the receiving node. The invention is particularly useful for wavelength division multiplexed (WDM) optical rings.