There are provided an information storage medium capable of real-time recordingplayback of digital moving picture information, and a digital information recordingplayback system using this medium. Each conference bridge within multiple communication groups determines which local communication unit is a dominant local communication unit, quantizes that dominant local communication unit’s signal, and transmits the quantized signal of the dominant local communication unit via signaling channels to the other conference bridges. The invention, which is particularly useful in cryptographically protected networks that run the TCPIP protocol stack, allows fine-grained flow control of individual traffic classes because it can determine, for example, how various classes of data traffic should be ordered and transmitted through a network.