BitTorrent Experiments on Testbeds: A Study of the Impact of Network Latencies

In this paper, we study the impact of network latency on the time required to download a file distributed using BitTorrent. This study is essential to understand if testbeds can be used for experimental evaluation of BitTorrent. We observe that the network latency has a marginal impact on the time required to download a file; hence, BitTorrent experiments can performed on testbeds

Quels réseaux pour les Big Data?

National audienceUn déluge de données est à prévoir dans les années à venir. Les utilisateurs de réseaux sociaux et l’Internet des objets, pour ne citer que ces deux exemples, génèrent déjà de grands volumes de données variées qui devront être transmises, enregistrées et traitées à grande vitesse. Les architectures et protocoles réseaux devront donc être suffisamment flexibles pour supporter la collecte et le traitement de ces Big Data à différentes échelles. Les réseaux sont donc une pièce essentielle pour le support des Big Data. Cet article décrit brièvement les évolutions des réseaux pour un support efficace de la collecte et du traitement des Big Data

Hight performance implementation of communication subsystems

New applications with specific communication requirements are now being considered. These requirements put stringent constraints on both the performance and the service provided by communication protocols over high speed networks. The performance enhancement of these protocols is an essential step toward the building of high performance communication subsystems. In this paper, we present work on the high speed implementation of both presentation and transport functions. We show how Integrated Layer Processing based optimizations increase the performance of costly data manipulation functions. We also present a framework for the design of integrated communication subsystems based on Application Level Framing and Integrated Layer Processing

Pushing BitTorrent Locality to the Limit

Peer-to-peer (P2P) locality has recently raised a lot of interest in the community. Indeed, whereas P2P content distribution enables financial savings for the content providers, it dramatically increases the traffic on inter-ISP links. To solve this issue, the idea to keep a fraction of the P2P traffic local to each ISP was introduced a few years ago. Since then, P2P solutions exploiting locality have been introduced. However, several fundamental issues on locality still need to be explored. In particular, how far can we push locality, and what is, at the scale of the Internet, the reduction of traffic that can be achieved with locality? In this paper, we perform extensive experiments on a controlled environment with up to 10 000 BitTorrent clients to evaluate the impact of high locality on inter-ISP links traffic and peers download completion time. We introduce two simple mechanisms that make high locality possible in challenging scenarios and we show that we save up to several orders of magnitude inter-ISP traffic compared to traditional locality without adversely impacting peers download completion time. In addition, we crawled 214 443 torrents representing 6 113 224 unique peers spread among 9 605 ASes. We show that whereas the torrents we crawled generated 11.6 petabytes of inter-ISP traffic, our locality policy implemented for all torrents would have reduced the global inter-ISP traffic by 40%

I Know Where You are and What You are Sharing: Exploiting P2P Communications to Invade Users' Privacy

In this paper, we show how to exploit real-time communication applications to determine the IP address of a targeted user. We focus our study on Skype, although other real-time communication applications may have similar privacy issues. We first design a scheme that calls an identified targeted user inconspicuously to find his IP address, which can be done even if he is behind a NAT. By calling the user periodically, we can then observe the mobility of the user. We show how to scale the scheme to observe the mobility patterns of tens of thousands of users. We also consider the linkability threat, in which the identified user is linked to his Internet usage. We illustrate this threat by combining Skype and BitTorrent to show that it is possible to determine the file-sharing usage of identified users. We devise a scheme based on the identification field of the IP datagrams to verify with high accuracy whether the identified user is participating in specific torrents. We conclude that any Internet user can leverage Skype, and potentially other real-time communication systems, to observe the mobility and file-sharing usage of tens of millions of identified users.Comment: This is the authors' version of the ACM/USENIX Internet Measurement Conference (IMC) 2011 pape

Spying the World from your Laptop -- Identifying and Profiling Content Providers and Big Downloaders in BitTorrent

This paper presents a set of exploits an adversary can use to continuously spy on most BitTorrent users of the Internet from a single machine and for a long period of time. Using these exploits for a period of 103 days, we collected 148 million IPs downloading 2 billion copies of contents. We identify the IP address of the content providers for 70% of the BitTorrent contents we spied on. We show that a few content providers inject most contents into BitTorrent and that those content providers are located in foreign data centers. We also show that an adversary can compromise the privacy of any peer in BitTorrent and identify the big downloaders that we define as the peers who subscribe to a large number of contents. This infringement on users' privacy poses a significant impediment to the legal adoption of BitTorrent

A Reliable multicast protocol for a white board application

This paper describes a proposed mechanism for reliable multicast protocol working on top of unreliable network service and making efficient use of the underlying multicast facilities available on the Internet. The primary goal is to provide a reliable multicast transport for a multi-user shared workspace application which is commonly used with other interactive video or audio conferencing tools

Tag-based Fair Bandwidth Sharing for Responsive and Unresponsive flows

Finding an appropriate end to end congestion control scheme for each type of flow, such as real-time or multicast flows, may be difficult. But it becomes even more complex to have these schemes be friendly among themselves and with TCP. The assistance of routers within the network for fair bandwidth sharing among the flows is therefore helpful. However, most of the existing mechanisms that provide this fair sharing imply complex buffer management and maintaining flow state in the routers. In this paper, we propose to realize this fair bandwidth sharing \it without per-flow state in the routers, using only a trivial queueing discipline. Packets are tagged near the source, depending on the nature of the flow. In the core of the network, routers use FIFO queues, and simply drop the packet with the highest tag value in case of congestion. We call our scheme \TUF, Tag-based Fair Queueing for Responsive and Unresponsive Flows, and compare it with the Core Stateless Fair Queueing (CSFQ) proposed recently by Stoica et al \citeStoica98S. We believe our approach is simpler, avoids in particular parameter tuning and label rewriting in the core routers, while providing similar performances. Moreover, tagging flows depending on their responsivenes- s to losses, as proposed in \TUF, avoids poor performances in bursty environme- nts, as in CSFQ

A Circuit-based Approach for Routing in Unidirectional Links Networks

Current routing protocols assume that routers are connected by bidirectional links. However, in an increasing number of configurations, pairs of routers may only be connected by unidirectional links. Examples of such configurations include ad-hoc packet radio networks, some satellite and cable networks, etc. Specific protocols are needed to support dynamic routing over these configurations. In this report, we first discuss the applicability of current techniques to the support of dynamic routing in a network where all routers are connected by unidirectional links (UDLs). We show that these techniques cannot be used without modifications because of specific UDL characteristics. We then present an unidirectional link routing protocol based on circuit detection which allows dynamic routing over unidirectional links, and describes its features and behaviour

Optimization of GEO Satellite Links Deployment in the Internet

As the satellite technology will be one of the main components of the Next Generation Internet (NGI), a naturally occurring question concerns the feasibility of providing an optimal satellite-based Internet access. In this paper, we are interested in GEO satellite links deployment in the Internet by addressing the problem of terrestrial-satellite hybrid network optimization for which we propose a general architecture. We devide the general optimization problem into several sub-problems which can be resolved separately. Each sub-problem treats a specific type of traffic and it is defined by a set of inputs, variables, goals, and constraints. The global GEO satellite links deployment optimization heuristic that we propose attempts to determine the optimal hybrid topology which minimizes performance metrics such as delay, throughput, call blocking probabilities, and network cost. Two main steps compose the proposed heuristic: performance evaluation step and satellite uplink position finding step. During the first step we try to determine values of performance metrics of studied traffic and in the second one, we look for the optimal position where to add the current satellite uplink in order to optimize performance criteria. We present in details a case study dealing with multicast traffic optimization during the deployment of GEO satellite links in the Internet. We develop a configuration policy of PIM-SM in hybrid networks concerning the choice of the list of Rendezvous Point (RPs) and the switching from the RP-routed tree to the shortest path tree. This policy provides an optimal use of satellite links for multicast transfer. The obtained results demonstrate the ability of the proposed optimization method to improve multicast performan- ce criteria and to determine effectively satellite uplinks positions using PIM-SM combined with UDLR (UniDirectional Link Routing)