"Don't let the stack get stuck": A novel approach for designing efficient stackable routers.

Stackable Routers, i.e. a class of independent routing units operating together as a single router, constitute an affordable scalable approach for coping with the growing networking requirements of organizations. In this study, we investigate several design problems of stackable routers and develop novel schemes for improving their performance. First, we formalize a mathematical model for optimizing the network topology in terms of throughput and delay, while obeying constraints in the number of ports of each internal routing unit. We then consider the problem of minimizing the diameter of the interconnection topology, as a measure of maximum delay, and establish efficient near-to optimal (explicit) topologies. Furthermore, we also consider the problem of maximizing the throughput of a stackable router. We show its hardness and derive bounds for the optimal solution. While, traditionally, the different routing units of a stackable router are linked together in a ring topology, through simulations we show that a major improvement in the diameter of stackable routers can be accomplished even through the employment of randomlygenerated topologies. Finally, we investigate the basic problem of constructing a feasible stackable router and establish some fundamental properties of the required structure of the routing units.