Methods for revealing and reshaping the African Internet Ecosystem as a case study for developing regions: from isolated networks to a connected continent

Mención Internacional en el título de doctorWhile connecting end-users worldwide, the Internet increasingly promotes local development by making challenges much simpler to overcome, regardless of the field in which it is used: governance, economy, education, health, etc. However, African Network Information Centre (AfriNIC), the Regional Internet Registry (RIR) of Africa, is characterized by the lowest Internet penetration: 28.6% as of March 2017 compared to an average of 49.7% worldwide according to the International Telecommunication Union (ITU) estimates [139]. Moreover, end-users experience a poor Quality of Service (QoS) provided at high costs. It is thus of interest to enlarge the Internet footprint in such under-connected regions and determine where the situation can be improved. Along these lines, this doctoral thesis thoroughly inspects, using both active and passive data analysis, the critical aspects of the African Internet ecosystem and outlines the milestones of a methodology that could be adopted for achieving similar purposes in other developing regions. The thesis first presents our efforts to help build measurements infrastructures for alleviating the shortage of a diversified range of Vantage Points (VPs) in the region, as we cannot improve what we can not measure. It then unveils our timely and longitudinal inspection of the African interdomain routing using the enhanced RIPE Atlas measurements infrastructure for filling the lack of knowledge of both IPv4 and IPv6 topologies interconnecting local Internet Service Providers (ISPs). It notably proposes reproducible data analysis techniques suitable for the treatment of any set of similar measurements to infer the behavior of ISPs in the region. The results show a large variety of transit habits, which depend on socio-economic factors such as the language, the currency area, or the geographic location of the country in which the ISP operates. They indicate the prevailing dominance of ISPs based outside Africa for the provision of intracontinental paths, but also shed light on the efforts of stakeholders for traffic localization. Next, the thesis investigates the causes and impacts of congestion in the African IXP substrate, as the prevalence of this endemic phenomenon in local Internet markets may hinder their growth. Towards this end, Ark monitors were deployed at six strategically selected local Internet eXchange Points (IXPs) and used for collecting Time-Sequence Latency Probes (TSLP) measurements during a whole year. The analysis of these datasets reveals no evidence of widespread congestion: only 2.2% of the monitored links experienced noticeable indication of congestion, thus promoting peering. The causes of these events were identified during IXP operator interviews, showing how essential collaboration with stakeholders is to understanding the causes of performance degradations. As part of the Internet Society (ISOC) strategy to allow the Internet community to profile the IXPs of a particular region and monitor their evolution, a route-collector data analyzer was then developed and afterward, it was deployed and tested in AfriNIC. This open source web platform titled the “African” Route-collectors Data Analyzer (ARDA) provides metrics, which picture in real-time the status of interconnection at different levels, using public routing information available at local route-collectors with a peering viewpoint of the Internet. The results highlight that a small proportion of Autonomous System Numbers (ASNs) assigned by AfriNIC (17 %) are peering in the region, a fraction that remained static from April to September 2017 despite the significant growth of IXPs in some countries. They show how ARDA can help detect the impact of a policy on the IXP substrate and help ISPs worldwide identify new interconnection opportunities in Africa, the targeted region. Since broadening the underlying network is not useful without appropriately provisioned services to exploit it, the thesis then delves into the availability and utilization of the web infrastructure serving the continent. Towards this end, a comprehensive measurement methodology is applied to collect data from various sources. A focus on Google reveals that its content infrastructure in Africa is, indeed, expanding; nevertheless, much of its web content is still served from the United States (US) and Europe, although being the most popular content source in many African countries. Further, the same analysis is repeated across top global and regional websites, showing that even top African websites prefer to host their content abroad. Following that, the primary bottlenecks faced by Content Providers (CPs) in the region such as the lack of peering between the networks hosting our probes and poorly configured DNS resolvers are explored to outline proposals for further ISP and CP deployments. Considering the above, an option to enrich connectivity and incentivize CPs to establish a presence in the region is to interconnect ISPs present at isolated IXPs by creating a distributed IXP layout spanning the continent. In this respect, the thesis finally provides a four-step interconnection scheme, which parameterizes socio-economic, geographical, and political factors using public datasets. It demonstrates that this constrained solution doubles the percentage of continental intra-African paths, reduces their length, and drastically decreases the median of their Round Trip Times (RTTs) as well as RTTs to ASes hosting the top 10 global and top 10 regional Alexa websites. We hope that quantitatively demonstrating the benefits of this framework will incentivize ISPs to intensify peering and CPs to increase their presence, for enabling fast, affordable, and available access at the Internet frontier.Programa Oficial de Doctorado en Ingeniería TelemáticaPresidente: David Fernández Cambronero.- Secretario: Alberto García Martínez.- Vocal: Cristel Pelsse

A system for profiling the IXPs in a region and monitoring their growth: spotlight at the internet frontier

This work aims at designing and implementing a system able to profile and help manage the set of Internet eXchange Points (IXPs) in an Internet region. As part of the Internet Society's strategy to help monitor and understand the evolution of IXPs in a particular region, a route-collector data analyzer tool was developed before being deployed and tested in AfriNIC. In fact, traffic localization efforts in the African peering ecosystem would be more sustained, and their efficacy assessed if they were supported by a platform, which evaluates and reports in real time about their impact on the Internet. We, thus, built the “African” Route-collectors Data Analyzer (ARDA), an open source web platform for analyzing publicly available routing information collected since 2005, by local route-collectors. ARDA evaluates predefined metrics that picture the status of the interconnection at local, national, and regional levels. It shows that a small proportion of AfriNIC ASes (roughly 17%) are peering in the region. Through them, 58% of all African networks are visible at one IXP or more. These have been static from April to September 2017, and even February 2018, underlining the need for increased efforts to improve local interconnectivity. We show how ARDA can help detect the impact of policies on the growth of local IXPs or continually provide the community with up-to-date empirical data on the evolution of the IXP substrate. Given its features, this tool will be a helpful compass for stakeholders in the quest for better traffic localization and new interconnection opportunities in the targeted region.This work was partially funded by the Internet Society (ISOC). Support to this work was also provided by IMDEA Networks Institute, the National Science Foundation (NSF) CNS-1414177, and NSF OAC-1724853.We are grateful to Nishal Goburdhan and Dibya Khatiwada for their technical support as well as to The African IXP Association (Af-IX), Packet Clearing House (PCH), and Hisham Ibrahim for their cooperation.Publicad

BGP-Multipath Routing in the Internet

BGP-Multipath, or BGP-M, is a routing technique for balancing traffic load in the Internet. It enables a Border Gateway Protocol (BGP) border router to install multiple ‘equally-good’ paths to a destination prefix. While other multipath routing techniques are deployed at internal routers, BGP-M is deployed at border routers where traffic is shared on multiple border links between Autonomous Systems (ASes). Although there are a considerable number of research efforts on multipath routing, there is so far no dedicated measurement or study on BGP-M in the literature. This thesis presents the first systematic study on BGP-M. I proposed a novel approach to inferring the deployment of BGP-M by querying Looking Glass (LG) servers. I conducted a detailed investigation on the deployment of BGP-M in the Internet. I also analysed BGP-M’s routing properties based on traceroute measurements using RIPE Atlas probes. My research has revealed that BGP-M has already been used in the Internet. In particular, Hurricane Electric (AS6939), a Tier-1 network operator, has deployed BGP-M at border routers across its global network to hundreds of its neighbour ASes on both IPv4 and IPv6 Internet. My research has provided the state-of-the-art knowledge and insights in the deployment, configuration and operation of BGP-M. The data, methods and analysis introduced in this thesis can be immensely valuable to researchers, network operators and regulators who are interested in improving the performance and security of Internet routing. This work has raised awareness of BGP-M and may promote more deployment of BGP-M in future because BGP-M not only provides all benefits of multipath routing but also has distinct advantages in terms of flexibility, compatibility and transparency

On the latency impact of remote peering

Internet Exchange Points (IXPs) play an essential role in the Internet, providing a fabric for thousands of Autonomous Systems (ASes) to interconnect. Initially designed to keep local traffic local, IXPs now interconnect ASes all over the world, and the premise that IXP routes should be shorter and faster than routes through a transit provider may not be valid anymore. Using BGP views from eight IXPs (three in Brazil, two in the U.S., and one each in London, Amsterdam, and Johannesburg), a transit connection at each of these locations, and latency measurements we collected in May 2021, we compare the latency to reach the same addresses using routes from remote peers, local peers, and transit providers. For four of these IXPs, at least 71.4% of prefixes advertised by remote peers also had a local peering route, BGP generally preferred the remote route due to its shorter AS path, but the local route had lower latency than the remote route in the majority of cases. When a remote route was the only peering route available at an IXP, it had slightly lower latency than a corresponding transit route available outside the IXP for >57.6% of the prefixes for seven of the eight IXPs

On the latency and routing impacts of remote peering to the Internet

Remote peering (RP) has crucially altered the Internet topology and its economics. In creasingly popular thanks to its lower costs and simplicity, RP has shifted the member base of Internet eXchange Points (IXPs) from strictly local to include ASes located any where in the world. While the popularity of RP is well understood, its implications on Internet routing and performance are not. In this thesis, we perform a comprehensive measurement study of RP in the wild, based on a representative set of IXPs (including some of the largest ones in the world, covering the five continents). We first identify the challenges of inferring remote peering and the limitations of the existing methodologies. Next, we perform active measurements to identify the deployment of remote IXP inter faces and announced prefixes in these IXPs, including a longitudinal analysis to observe RP growth over one and a half years. We use the RP inferences on IXPs to investigate whether RP routes announced at IXPs tend to be preferred over local ones and what are their latency and latency variability impacts when using different interconnection meth ods (remote peering, local peering, and transit) to deliver traffic. Next, we asses the RP latency impact when using a remote connection to international IXPs and reaching prefix destinations announced by their members. We perform measurements leveraging the in frastructure of a large Latin American RP reseller and compare the latency to reach IXP prefixes via RP and four Transit providers. Finally, we glimpse some of the RP impli cations on Internet routing. We evaluate how RP can considerably affect IXP members’ connection stability, potentially introduce routing detours caused by prefix announcement mispractices and be the target of traffic engineering by ASes using BGP communities

Inferring persistent interdomain congestion

There is significant interest in the technical and policy communities regarding the extent, scope, and consumer harm of persistent interdomain congestion. We provide empirical grounding for discussions of interdomain congestion by developing a system and method to measure congestion on thousands of interdomain links without direct access to them. We implement a system based on the Time Series Latency Probes (TSLP) technique that identifies links with evidence of recurring congestion suggestive of an under-provisioned link. We deploy our system at 86 vantage points worldwide and show that congestion inferred using our lightweight TSLP method correlates with other metrics of interconnection performance impairment. We use our method to study interdomain links of eight large U.S. broadband access providers from March 2016 to December 2017, and validate our inferences against ground-truth traffic statistics from two of the providers. For the period of time over which we gathered measurements, we did not find evidence of widespread endemic congestion on interdomain links between access ISPs and directly connected transit and content providers, although some such links exhibited recurring congestion patterns. We describe limitations, open challenges, and a path toward the use of this method for large-scale third-party monitoring of the Internet interconnection ecosystem

O Peer, Where Art Thou?:Uncovering Remote Peering Interconnections at IXPs

Internet eXchange Points (IXPs) are Internet hubs that provide the switching infrastructure to interconnect networks and exchange traffic. While the initial goal of IXPs was to bring together networks residing in the same city or country, and thus keep local traffic local, we observe that this model is gradually shifting. Many networks connect to IXPs without having physical presence at their switch(es). This practice, called Remote Peering, is changing the Internet topology and economy, and has become subject of a contentious debate within the network operators community. However, despite the increasing attention it is drawing, the understanding of the characteristics and impact of remote peering is limited. In this work, we remove the veil between remote peering and IXPs, by introducing and thoroughly validating a methodology for discovering remote peers at IXPs. We (i) infer remote peers globally, with high accuracy (>95%), (ii) study the evolution of remote peering in time, and (iii) evaluate its impact on Internet performance and resilience. We observe that remote peering is a significantly common practice in all the IXPs studied; for the largest IXPs, remote peers account for 40% of their member base. We also show that today IXP growth is mainly driven by remote peering, which contributes two times more than local peering

From the edge to the core : towards informed vantage point selection for internet measurement studies

Since the early days of the Internet, measurement scientists are trying to keep up with the fast-paced development of the Internet. As the Internet grew organically over time and without build-in measurability, this process requires many workarounds and due diligence. As a result, every measurement study is only as good as the data it relies on. Moreover, data quality is relative to the research question—a data set suitable to analyze one problem may be insufficient for another. This is entirely expected as the Internet is decentralized, i.e., there is no single observation point from which we can assess the complete state of the Internet. Because of that, every measurement study needs specifically selected vantage points, which fit the research question. In this thesis, we present three different vantage points across the Internet topology— from the edge to the Internet core. We discuss their specific features, suitability for different kinds of research questions, and how to work with the corresponding data. The data sets obtained at the presented vantage points allow us to conduct three different measurement studies and shed light on the following aspects: (a) The prevalence of IP source address spoofing at a large European Internet Exchange Point (IXP), (b) the propagation distance of BGP communities, an optional transitive BGP attribute used for traffic engineering, and (c) the impact of the global COVID-19 pandemic on Internet usage behavior at a large Internet Service Provider (ISP) and three IXPs.Seit den frühen Tagen des Internets versuchen Forscher im Bereich Internet Measu- rement, mit der rasanten Entwicklung des des Internets Schritt zu halten. Da das Internet im Laufe der Zeit organisch gewachsen ist und nicht mit Blick auf Messbar- keit entwickelt wurde, erfordert dieser Prozess eine Meg Workarounds und Sorgfalt. Jede Measurement Studie ist nur so gut wie die Daten, auf die sie sich stützt. Und Datenqualität ist relativ zur Forschungsfrage - ein Datensatz, der für die Analyse eines Problems geeiget ist, kann für ein anderes unzureichend sein. Dies ist durchaus zu erwarten, da das Internet dezentralisiert ist, d. h. es gibt keinen einzigen Be- obachtungspunkt, von dem aus wir den gesamten Zustand des Internets beurteilen können. Aus diesem Grund benötigt jede Measurement Studie gezielt ausgewählte Beobachtungspunkte, die zur Forschungsfrage passen. In dieser Arbeit stellen wir drei verschiedene Beobachtungspunkte vor, die sich über die gsamte Internet-Topologie erstrecken— vom Rand bis zum Kern des Internets. Wir diskutieren ihre spezifischen Eigenschaften, ihre Eignung für verschiedene Klas- sen von Forschungsfragen und den Umgang mit den entsprechenden Daten. Die an den vorgestellten Beobachtungspunkten gewonnenen Datensätze ermöglichen uns die Durchführung von drei verschiedenen Measurement Studien und damit die folgenden Aspekte zu beleuchten: (a) Die Prävalenz von IP Source Address Spoofing bei einem großen europäischen Internet Exchange Point (IXP), (b) die Ausbreitungsdistanz von BGP-Communities, ein optionales transitives BGP-Attribut, das Anwendung im Bereich Traffic-Enigneering findet sowie (c) die Auswirkungen der globalen COVID- 19-Pandemie auf das Internet-Nutzungsverhalten an einem großen Internet Service Provider (ISP) und drei IXPs

Evaluating and Improving Internet Load Balancing with Large-Scale Latency Measurements

Load balancing is used in the Internet to distribute load across resources at different levels, from global load balancing that distributes client requests across servers at the Internet level to path-level load balancing that balances traffic across load-balanced paths. These load balancing algorithms generally work under certain assumptions on performance similarity. Specifically, global load balancing divides the Internet address space into client aggregations and assumes that clients in the same aggregation have similar performance to the same server; load-balanced paths are generally selected for load balancing as if they have similar performance. However, as performance similarity is typically achieved with similarity in path properties, e.g., topology and hop count, which do not necessarily lead to similar performance, performance between clients in the same aggregation and between load-balanced paths could differ significantly. This dissertation evaluates and improves global and path-level load balancing in terms of performance similarity. We achieve this with large-scale latency measurements, which not only allow us to systematically identify and evaluate the performance issues of Internet load balancing at scale, but also enable us to develop data-driven approaches to improve the performance. Specifically, this dissertation consists of three parts. First, we study the issues of existing client aggregations for global load balancing and then design AP-atoms, a data-driven client aggregation learned from passive large-scale latency measurements. Second, we show that the latency imbalance between load-balanced paths, previously deemed insignificant, is now both significant and prevalent. We present Flipr, a network prober that actively collects large-scale latency measurements to characterize the latency imbalance issue. Lastly, we design another network prober, Congi, that can detect congestion at scale and use Congi to study the congestion imbalance problem at scale. For both latency and congestion imbalance, we demonstrate that they could greatly affect the performance of various applications.PHDComputer Science & EngineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/168012/1/yibo_1.pd

Social work with airports passengers

Social work at the airport is in to offer to passengers social services. The main methodological position is that people are under stress, which characterized by a particular set of characteristics in appearance and behavior. In such circumstances passenger attracts in his actions some attention. Only person whom he trusts can help him with the documents or psychologically