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Disruptive events, such as large-scale power outages, undersea cable cuts, or security attacks, could have an impact on the Internet and cause the Internet to deviate from its normal state of operation, which we also refer to as an “Internet earthquake.” As the Internet is a large, complex moving target, unfortunately little research has been done to define, observe, quantify, and analyze such impact on the Internet, whether it is during a past event period or in real time. In this paper, we devise an Internet seismograph, or I-seismograph, to fill this gap. Since routing is the most basic function of the Internet and the Border Gateway Protocol (BGP) is the de facto standard inter-domain routing protocol, we focus on BGP to observe, measure, and analyze the Internet earthquakes. After defining what an impact to BGP entails, we describe how I-seismograph observes and measures the impact, exemplify its usage during both old and recent disruptive events, and further validate its accuracy and convergency. Finally, we show that I-seismograph can further be used to help analyze what happened to BGP while BGP experienced an impact, including which autonomous systems (AS) were affected most or which AS paths or path segments surged significantly in BGP updates during an Internet earthquake. [ABSTRACT FROM PUBLISHER]

In the last decade, many studies have used the Internet autonomous system (AS)-level topology to perform several analyses, from discovering its graph properties to assessing its impact on the effectiveness of worm-containment strategies. Yet, the Border Gateway Protocol (BGP) data used to reveal the topologies are far from complete. Our contribution is threefold. First, we analyze BGP data currently gathered by the most famous route collector projects, highlighting and explaining the causes of their incompleteness. We found that large areas of the Internet are not properly captured due to the geographical location of route collector feeders and due to BGP filters, such as export policies and decision processes. Second, we propose a methodology based on a new metric, named p2c-distance, which is able to: 1) identify the minimum number of ASs required to obtain an Internet AS-level topology that is closer to reality; and 2) identify a ranking list of these ASs to show that it is possible to obtain nonnegligible coverage improvements with a limited number of appropriately chosen feeding ASs. Third, we characterize the ASs that were found to be part of the solution of the above covering problems. We found that the route collectors are rarely connected to these ASs, thus highlighting that much effort is needed to devise a route collector infrastructure that ideally would be able to capture a complete view of the Internet. [ABSTRACT FROM PUBLISHER]

The network infrastructure of Internet service providers (ISPs) undergoes constant evolution. Whenever new requirements arise (e.g., the deployment of a new Point of Presence or a change in the business relationship with a neighboring ISP), operators need to change the configuration of the network. Due to the complexity of the Border Gateway Protocol (BGP) and the lack of methodologies and tools, maintaining service availability during reconfigurations that involve BGP is a challenge for operators. In this paper, we show that the current best practices to reconfigure BGP do not provide guarantees with respect to traffic disruptions. Then, we study the problem of finding an operational ordering of BGP reconfiguration steps that guarantees no packet loss. Unfortunately, finding such an operational ordering, when it exists, is computationally hard. To enable lossless reconfigurations, we propose a framework that extends current features of carrier-grade routers to run two BGP control planes in parallel. We present a prototype implementation and show the effectiveness of our framework through a case study. [ABSTRACT FROM PUBLISHER]

Border Gateway Protocol (BGP) allows providers to express complex routing policies preserving high degrees of autonomy. However, unrestricted routing policies can adversely impact routing stability. A key concept to understand the interplay between autonomy and expressiveness on one side, and stability on the other side, is safety under filtering, i.e., guaranteed stability under autonomous usage of route filters. BGP route filters are used to selectively advertise specific routes to specific neighbors. In this paper, we provide a characterization of safety under filtering, filling the large gap between previously known necessary and sufficient conditions. Our characterization is based on the absence of a particular kind of dispute wheel, a structure involving circular dependencies among routing preferences. We exploit our result to show that networks admitting multiple stable states are provably unsafe under filtering, and the troublesome portion of the configuration can be pinpointed starting from the stable states alone. This is especially interesting from an operational point of view since networks with multiple stable states actually happen in practice (BGP wedgies). Finally, we show that adding filters to an existing configuration may lead to oscillations even if the configuration is safe under any link failure. Unexpectedly, we find policy configurations where misconfigured filters can do more harm than network faults. [ABSTRACT FROM PUBLISHER]

It is generally admitted that interdomain peering links represent nowadays the main bottleneck of the Internet, particularly because of lack of coordination between providers, which use independent and “selfish” routing policies. We are interested in identifying possible “light” coordination strategies that would allow carriers to better control their peering links while preserving their independence and respective interests. We propose a robust multipath routing coordination framework for peering carriers, which relies on the multiple-exit discriminator (MED) attribute of Border Gateway Protocol (BGP) as signaling medium. Our scheme relies on a game theory modeling, with a non-cooperative potential game considering both routing and congestions costs. Peering equilibrium multipath (PEMP) coordination policies can be implemented by selecting Pareto-superior Nash equilibria at each carrier. We compare different PEMP policies to BGP Multipath schemes by emulating a realistic peering scenario. Our results show that the routing cost can be decreased by roughly 10% with PEMP. We also show that the stability of routes can be significantly improved and that congestion can be practically avoided on the peering links. Finally, we discuss practical implementation aspects and extend the model to multiple players highlighting the possible incentives for the resulting extended peering framework. [ABSTRACT FROM PUBLISHER]

Despite significant efforts to obtain an accurate picture of the Internet's connectivity structure at the level of individual autonomous systems (ASes), much has remained unknown in terms of the quality of the inferred AS maps that have been widely used by the research community. In this paper, we assess the quality of the inferred Internet maps through case studies of a sample set of ASes. These case studies allow us to establish the ground truth of connectivity between this set of ASes and their directly connected neighbors. A direct comparison between the ground truth and inferred topology maps yield insights into questions such as which parts of the actual topology are adequately captured by the inferred maps, which parts are missing and why, and what is the percentage of missing links in these parts. This information is critical in assessing, for each class of real-world networking problems, whether the use of currently inferred AS maps or proposed AS topology models is, or is not, appropriate. More importantly, our newly gained insights also point to new directions towards building realistic and economically viable Internet topology maps. [ABSTRACT FROM AUTHOR]

Previous measurement studies have shown the existence of path exploration and slow convergence in the global Internet routing system, and a number of protocol enhancements have been proposed to remedy the problem. However, existing measurements were conducted only over a small number of testing prefixes. There has been no systematic study to quantify the pervasiveness of Border Gateway Protocol (BGP) slow convergence in the operational Internet, nor any known effort to deploy any of the proposed solutions. In this paper, we present our measurement results that identify BGP slow convergence events across the entire global routing table. Our data shows that the severity of path exploration and slow convergence varies depending on where prefixes are originated and where the observations are made in the Internet routing hierarchy. In general, routers in tier-1 Internet service providers (ISPs) observe less path exploration, hence they experience shorter convergence delays than routers in edge ASs; prefixes originated from tier-I ISPs also experience less path exploration than those originated from edge ASs. Furthermore, our data show that the convergence time of route fail-over events is similar to that of new route announcements and is significantly shorter than that of route failures. This observation is contrary to the widely held view from previous experiments but confirms our earlier analytical results. Our effort also led to the development of a path-preference inference method based on the path usage time, which can be used by future studies of BGP dynamics. [ABSTRACT FROM AUTHOR]