Peering vs transit: A game theoretical model for autonomous systems connectivity

Abstract

We propose a model to analyze the decisions taken by an Autonomous System (AS) when joining the Internet. We first define a realistic model for the interconnection costs incurred and then we use this cost model to perform a game theoretic analysis of the decisions related to the creation of new links in the Internet. The proposed model doesn't fall into the standard category of routing games, hence we devise new tools to solve it by exploiting peculiar properties of our game. We prove analytically the existence of multiple equilibria for specific cases, and provide an algorithm to compute the stable ones. The analysis of the model's outcome highlights the existence of a Price of Anarchy (PoA) and a Price of Stability (PoS), originated by the non-cooperative behavior of the ASes, which optimize their cost function in a selfish and decentralized manner. We further observe the presence of competition between the facilities providing either transit or peering connectivity, caused by the cost differences between these two interconnection strategies.

A game theoretical study of peering vs transit in the internet

“…The main contributions of this work are twofold. First of all, we extend results presented in [1], showing the existence of equilibria and an algorithm converging to them even for generalized version of the game therein proposed. Moreover, we use simulation to show that the main findings of [1], like the emerging competition (first observed in [9]) between the two facilities enabling either transit or peering connectivity, still hold for more general cases.…”

“…First of all, we extend results presented in [1], showing the existence of equilibria and an algorithm converging to them even for generalized version of the game therein proposed. Moreover, we use simulation to show that the main findings of [1], like the emerging competition (first observed in [9]) between the two facilities enabling either transit or peering connectivity, still hold for more general cases. Even more interestingly, we notice that also for asymmetric scenarios, the equilibrium reached suggests that players tend to be symmetric with respect to the internet exchange points and send their asymmetric traffic quota via the transit service providers.…”

“…The approach of [1] is quite different, since it tries to understand how connections are formed as the result of a game between ASes. In this context, the realm of network formation games (see [19], [20]) investigates existence and properties of equilibria in a network created by rational players, each one with their costs and utility functions.…”

“…Given all the difficulties arising when trying to model the whole network formation process, [1] prefers to analyze the decision problem faced by ASes connecting to a pre-existing network, in order to deliver traffic according to some demands. Authors of [22] present a game-theoretic modelization of a network where access providers optimize their costs when connecting to a subset of content provider.…”

“…In fact, peering policies and IXPs brought new variables to the problem, such as the fact that the outcome of an AS decision also depends on what other ASes, dealing with the same problem, do: due to this aspect, we believe that a game-theoretical analysis of the problem would be highly insightful. While, for the sake of mathematical tractability, it is impossible to realistically model the whole decision space of an AS, the model proposed in [1] keeps into account many realistic factors like port capacity, AS reachability and realistic interconnection costs. The model focuses on access provider ASes who need to set up their connections and route traffic, and highlights the fundamental difference between transit and peering interconnection policies.…”