A packet communications network for transmitting data between nodes by the use of cell slots circulating the network includes a center node inserted in the ring network for sequentially generating, at a selected rate, first and second types of cell slots interleavingly for transmitting first and second types of data, respectively. Each cell slot has a type code for identifying either one of the first and second types, and a status code for identifying the different status of the cells. Each node detects whether the received cell is the first type or the second type. If the received cell is the first type, it is used for transmitting the connection-oriented data under MARS system. If the received cell is the second type, it is used for transmitting the connectionless data under ATMR system.