Techniques for transmitting data packets on a shared channel in a data communications network, include determining a time slot interval, T, based on a longest data packet to be transmitted on a shared channel in a data communications network. At a first node in the data communications network a local base time, t0, is determined equal to a time at an end of receipt of a successful acknowledgement control packet on the shared channel. A local data packet is transmitted from the first node onto the shared channel at a transmit time that is an integer multiple n of T after the local base time t0. The local data packet is determined to be successfully transmitted when a successful acknowledgement control packet that uniquely indicates the local data packet is received on the shared channel within the interval T of transmitting the local data packet.