BGP and inter-AS economic relationships

The structure of the Internet is still unknown even if it pro- vides well-known services for a large part of the worldwide population. Its current conguration is the result of complex economic interaction developed in the last 20 years among important carriers and ISPs (i.e. ASes). Although with slight success, in the last few years some research work tried to shed light on the economic relationships established among ASes. Typical approaches employed in the above work proceed along two lines: rst, data from BGP monitors spread out all over the world is gath- ered to infer an Internet AS-level topology graph, and second heuristics taking as input this graph are applied to get economic tags associated to all edges between nodes (i.e. ASes). In this paper we propose an in- novative tagging approach leveraging on the lifetime of an AS path to infer the economic relationships on all edges joining the ASes crossed by the path itself, without cutting-o backup links, that bring economic information as well as stable links. The major ndings of our approach can be summarized as follows: (data hygiene before infer the Internet AS-level topology graph) study on AS paths loops, human error and their impact on data correctness ( life-time based tagging we do not cut-o bakcup links) we evidence those tags are inferred only from a partial viewpoint we evidence the maximum lifetime of the AS path that have contributed to infer the tag of each connection { classication of candidate Tier-1 AS based on three indexes re ecting the importance of an AS { explanation and life-time study of non valley-free AS path

An online distributed algorithm for inferring policy routing configurations

We present an online distributed algorithm, the Causation Logging Algorithm (CLA), in which Autonomous Systems (ASes) in the Internet individually report route oscillations/flaps they experience to a central Internet Routing Registry (IRR). The IRR aggregates these reports and may observe what we call causation chains where each node on the chain caused a route flap at the next node along the chain. A chain may also have a causation cycle. The type of an observed causation chain/cycle allows the IRR to infer the underlying policy routing configuration (i.e. the system of economic relationships and constraints on route/path preferences). Our algorithm is based on a formal policy routing model that captures the propagation dynamics of route flaps under arbitrary changes in topology or path preferences. We derive invariant properties of causation chains/cycles for ASes which conform to economic relationships based on the popular Gao-Rexford model. The Gao-Rexford model is known to be safe in the sense that the system always converges to a stable set of paths under static conditions. Our CLA algorithm recovers the type/property of an observed causation chain of an underlying system and determines whether it conforms to the safe economic Gao-Rexford model. Causes for nonconformity can be diagnosed by comparing the properties of the causation chains with those predicted from different variants of the Gao-Rexford model

The Strategic Justification for BGP

The Internet consists of many administrative domains, or \emph{Autonomous Systems} (ASes), each owned by an economic entity (Microsoft, AT\&T, The Hebrew University, etc.). The task of ensuring interconnectivity between ASes, known as \emph{interdomain routing}, is currently handled by the \emph{Border Gateway Protocol} (BGP). ASes are self-interested and might be willing to manipulate BGP for their benefit. In this paper we present the strategic justification for using BGP for interdomain routing in today's Internet: We show that, in the realistic Gao-Rexford setting, BGP is immune to almost all forms of rational manipulation by ASes, and can easily be made immune to all such manipulations. The Gao-Rexford setting is said to accurately depict the current commercial relations between ASes in the Internet. Formally, we prove that a slight modification of BGP is incentive-compatible in \emph{ex-post Nash equilibrium}. Moreover, we show that, if a certain reasonable condition holds, then this slightly modified BGP is also \emph{collusion-proof} in ex-post Nash -- i.e., immune to rational manipulations even by \emph{coalitions} of \emph{any} size. Unlike previous works on achieving incentive-compatibility in interdomain routing, our results \emph{do not require any monetary transfer between ASes} (as is the case in practice). We also strengthen the Gao-Rexford constraints by proving that one of the three constraints can actually be enforced by the rationality of ASes if the two other constraints hold.Networks; Ex post Nash; Routing; rational manipulation; Border Gateway Protocol; Dispute Wheel

Connectivity measures for internet topologies.

The topology of the Internet has initially been modelled as an undirected graph, where vertices correspond to so-called Autonomous Systems (ASs),and edges correspond to physical links between pairs of ASs. However, in order to capture the impact of routing policies, it has recently become apparent that one needs to classify the edges according to the existing economic relationships (customer-provider, peer-to-peer or siblings) between the ASs. This leads to a directed graph model in which traffic can be sent only along so-called valley-free paths. Four different algorithms have been proposed in the literature for inferring AS relationships using publicly available data from routing tables. We investigate the differences in the graph models produced by these algorithms, focussing on connectivity measures. To this aim, we compute the maximum number of vertex-disjoint valley-free paths between ASs as well as the size of a minimum cut separating a pair of ASs. Although these problems are solvable in polynomial time for ordinary graphs, they are NP-hard in our setting. We formulate the two problems as integer programs, and we propose a number of exact algorithms for solving them. For the problem of finding the maximum number of vertex-disjoint paths, we discuss two algorithms; the first one is a branch-and-price algorithm based on the IP formulation, and the second algorithm is a non LP based branch-and-bound algorithm. For the problem of finding minimum cuts we use a branch-and-cut algo rithm, based on the IP formulation of this problem. Using these algorithms, we obtain exact solutions for both problems in reasonable time. It turns out that there is a large gap in terms of the connectivity measures between the undirected and directed models. This finding supports our conclusion that economic relationships need to be taken into account when building a topology of the Internet.Research; Internet;

Antitrust Analysis for the Internet Upstream Market: a BGP Approach

In this paper we study concentration in the European Internet upstream access market. Measurement of market concentration depends on correctly defining the market, but this is not always possible as Antitrust authorities often lack reliable pricing and traffic data. We present an alternative approach based on the inference of the Internet Operators interconnection policies using micro-data sourced from their Border Gateway Protocol tables. Firstly we propose a price-independent algorithm for defining both the vertical and geographical relevant market boundaries, then we calculate market concentration indexes using two novel metrics. These assess, for each undertaking, both its role in terms of essential network facility and of wholesale market dominance. The results, applied to four leading Internet Exchange Points in London, Amsterdam, Frankfurt and Milan, show that some vertical segments of these markets are extremely competitive, while others are highly concentrated, putting them within the special attention category of the Merger Guidelines

Interdomain routing and games

We present a game-theoretic model that captures many of the intricacies of \emph{interdomain routing} in today's Internet. In this model, the strategic agents are source nodes located on a network, who aim to send traffic to a unique destination node. The interaction between the agents is dynamic and complex -- asynchronous, sequential, and based on partial information. Best-reply dynamics in this model capture crucial aspects of the only interdomain routing protocol de facto, namely the Border Gateway Protocol (BGP). We study complexity and incentive-related issues in this model. Our main results are showing that in realistic and well-studied settings, BGP is incentive-compatible. I.e., not only does myopic behaviour of all players \emph{converge} to a ``stable'' routing outcome, but no player has motivation to unilaterally deviate from the protocol. Moreover, we show that even \emph{coalitions} of players of \emph{any} size cannot improve their routing outcomes by collaborating. Unlike the vast majority of works in mechanism design, our results do not require any monetary transfers (to or by the agents).Interdomain Routing; Network Games; BGP protocol;

Icebergs in the Clouds: the Other Risks of Cloud Computing

Cloud computing is appealing from management and efficiency perspectives, but brings risks both known and unknown. Well-known and hotly-debated information security risks, due to software vulnerabilities, insider attacks, and side-channels for example, may be only the "tip of the iceberg." As diverse, independently developed cloud services share ever more fluidly and aggressively multiplexed hardware resource pools, unpredictable interactions between load-balancing and other reactive mechanisms could lead to dynamic instabilities or "meltdowns." Non-transparent layering structures, where alternative cloud services may appear independent but share deep, hidden resource dependencies, may create unexpected and potentially catastrophic failure correlations, reminiscent of financial industry crashes. Finally, cloud computing exacerbates already-difficult digital preservation challenges, because only the provider of a cloud-based application or service can archive a "live," functional copy of a cloud artifact and its data for long-term cultural preservation. This paper explores these largely unrecognized risks, making the case that we should study them before our socioeconomic fabric becomes inextricably dependent on a convenient but potentially unstable computing model.Comment: 6 pages, 3 figure