An audio/video communication system includes plural network terminals. Each network terminal has a communication node and a stand-by node. Every node in a communication group has a first lower node connector and a second lower node connector, and is arranged to store a first value indicating a number of nodes in a first side diverging from the first lower node connector and a second value indicating a number of nodes in a second side diverging from the second lower node connector. A new node is added to the communication group such that the first value and the second value stored in each node is substantially equal, in order to define a balanced binary tree structure. Data sent from a node in the communication group reaches all other nodes in the communication group within a time proportional to a logarithm of the number of nodes in the communication group.