Secret information in communications networks

Abstract

Some users of a communications network may have more information about traffic on the network than do others - and this fact may be secret. Such information would allow the possessor to tailor its own traffic to the traffic of others, sending a larger amount of traffic when congestion is low and a smaller amount of traffic when congestion is high; this would help the possessor of secret information and (might) harm others. To study the impact of secret information we formulate a flow control game with incomplete information where users choose their flows in order to maximize their (expected) utilities given the actions of others. In this environment, the natural baseline notion is Bayesian Nash equilibrium (BNE); we establish the existence of BNE in pure strategies. To capture the effect of secret information, we assume that there is a user who knows the congestion created by other users, but that the presence of this user is not known by other users; thus this user has secret information. For this environment, we define a new equilibrium concept: the Bayesian Nash Equilibrium with Secret Information (BNE-SI) and establish its existence. We establish rigorous estimates for the benefit and harm that result from secret information; both the benefit and the harm are smaller for large networks than for small networks. Simulations confirm the estimates of benefit and harm for networks of different sizes and demonstrate that secret information may in fact benefit all users. Secret information may also harm other users in other scenarios. This analysis can be used as a starting point for securing communications networks, both from the network manager and the user's perspectives.