Routing and Peering in a Competitive Internet
Authors:	R. Johari J. Tsitsiklis
Published:	MIT, 2003
URL:	http://citeseer.ist.psu.edu/johari03routing.html
Entry Date:	2004-06-30
Abstract:	Today's Internet is a loose federation of independent network providers, each acting in their own self interest. In this paper, we consider some implications of this economic reality. Specifically, we consider how the incentives of the providers might determine where they choose to interconnect with each other; we show that for any given provider, determining an optimal placement of interconnection links is generally NP-complete. However, we present simple solutions for some special cases of this placement problem. We also consider the phenomenon of nearest-exit, or "hot-potato," routing, where outgoing traffic exits a provider's network as quickly as possible. If each link in a network is assessed a linear cost per unit flow through the link, we show that the total cost of nearest exit routing is no worse than three times the optimal cost. In the general case, with nonlinear cost functions, we consider allowing providers to charge each other for flow on their links. We study the efficiency of such a scheme, and arrive at bounds on the worst possible efficiency loss.
Results:	For cases where the two networks are both overlapping linear networks or trees, trivial or efficient methods for finding optimal solutions for each party are shown. For a simplified model of traffic in the linear networks, the optimal placement for both is n equally spaced links. A dynamic programming algorithm is given for more general traffic distributions. The optimal placement for tree networks is shown. In general cases, the networks will not agree on peering point placement. The number of peering points can be chosen so there is an agreement. A more general model is NP-complete. The combined cost between the networks of nearest exit routing is no more than 3 times the minimum combined cost. If pricing is done on traffic between the networks, there can be a loss of efficiency that cannot be generally bounded.