On the possibility of information propagation on graphs

The following model of information propagation is considered: Sources A1,...,An are given, each possessing certain information. If two sources can communicate with each other, then after a ‘call’ each will possess the total information which was known earlier to each one of them, separately. The question is whether the available communication system allows us to carry out a series of calls after which each one of the sources would possess the total information available to the subscribers A1,...,An.