Distributed floor control protocols for computer collaborative applications on overlay networks

Computer supported collaborative applications on overlay networks are gaining popularity among users who are geographically dispersed. Examples of these kinds of applications include video-conferencing, collaborative design and simulation, distance learning, and online games. One of the important issues in collaborative applications is floor control wherein the end-users coordinate among themselves to gain exclusive access to the communication channel. An end-user who wins the floor, sends message to all other participating end-users. In this paper, to solve the floor control problem we present an implementation and evaluation of ALOHA and distributed queue dual bus (DQDB) distributed MAC (medium access control) protocols on overlay networks. As an initial step in the implementation of these MAC protocols, we propose an algorithm to construct an efficient communication channel among the Network Service Nodes (NSNs) in the overlay network. We also show that our implementation scheme (first one among decentralized floor control protocols) preserves the causal ordering of messages. We compare the efficiencies of the proposed implementation of floor control protocols using an analytical model that is verified using extensive simulation experiments.