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

Transcending POSIX: The End of an Era?

In this article, we provide a holistic view of the Portable Operating System Interface (POSIX) abstractions by a systematic review of their historical evolution. We discuss some of the key factors that drove the evolution and identify the pitfalls that make them infeasible when building modern applications.Peer reviewe

NoSQL stores for coreless mobile networks

The goals of 5G networks — low latency, high bandwidth, and support for fast mobility — are non-trivial and they demand improvements across all involved technology fields. Researchers are therefore exploring approaches that leverage on network function virtualization and software-defined networking for meeting the demands of verticals expected to use 5G networks. One approach which appears promising is the concept of a coreless mobile network where the key network functions are placed at the edge of the network. In this article we focus on management of the user-context state in a coreless mobile network, and posit that these network functions can use a NoSQL data store for maintaining the user-context and other state variables. We first present an overview of promising NoSQL data stores and evaluate their suitability. We then present the results of benchmarking the Apache Geode data store as an example of a state management solution which could serve a coreless mobile network. During our tests we observe that the Apache Geode data store is, subject to its configuration, capable of delivering the data model, consistency, and high availability required by a coreless mobile network.Peer reviewe

Memory Management Support for Multi-Programmed Remote Direct Memory Access (RDMA) Systems

Current operating systems offer basic support for network interface controllers (NICs) supporting remote direct memory access (RDMA). Such support typically consists of a device driver responsible for configuring communication channels between the device and user-level processes but not involved in data transfer. Unlike standard NICs, RDMA-capable devices incorporate significant memory resources for address translation purposes. In a multi-programmed operating system (OS) environment, these memory resources must be efficiently shareable by multiple processes. For such sharing to occur in a fair manner, the OS and the device must cooperate to arbitrate access to NIC memory, similar to the way CPUs and OSes cooperate to arbitrate access to translation lookaside buffers (TLBs) or physical memory. A problem with this approach is that today’s RDMA NICs are not integrated into the functions provided by OS memory management systems. As a result, RDMA NIC hardware resources are often monopolized by a single application. In this paper, I propose two practical mechanisms to address this problem: (a) Use of RDMA only in kernel-resident I/O subsystems, transparent to user-level software; (b) An extended registration API and a kernel upcall mechanism delivering NIC TLB entry replacement notifications to user-level libraries. Both options are designed to re-instate the multiprogramming principles that are violated in early commercial RDMA systems

Experimental Assessment of BitTorrent Completion Time in Heterogeneous TCP/uTP swarms

BitTorrent, one of the most widespread used P2P application for file-sharing, recently got rid of TCP by introducing an application-level congestion control protocol named uTP. The aim of this new protocol is to efficiently use the available link capacity, while minimizing its interference with the rest of user traffic (e.g., Web, VoIP and gaming) sharing the same access bottleneck. In this paper we perform an experimental study of the impact of uTP on the torrent completion time, the metric that better captures the user experience. We run BitTorrent applications in a flash crowd scenario over a dedicated cluster platform, under both homogeneous and heterogeneous swarm population. Experiments show that an all-uTP swarms have shorter torrent download time with respect to all-TCP swarms. Interestingly, at the same time, we observe that even shorter completion times can be achieved under careful mixtures of TCP and uTP traffic.Comment: 14 pages, under submissio

From photons to big-data applications: terminating terabits

Computer architectures have entered a watershed as the quantity of network data generated by user applications exceeds the data-processing capacity of any individual computer end-system. It will become impossible to scale existing computer systems while a gap grows between the quantity of networked data and the capacity for per system data processing. Despite this, the growth in demand in both task variety and task complexity continues unabated. Networked computer systems provide a fertile environment in which new applications develop. As networked computer systems become akin to infrastructure, any limitation upon the growth in capacity and capabilities becomes an important constraint of concern to all computer users. Considering a networked computer system capable of processing terabits per second, as a benchmark for scalability, we critique the state of the art in commodity computing, and propose a wholesale reconsideration in the design of computer architectures and their attendant ecosystem. Our proposal seeks to reduce costs, save power and increase performance in a multi-scale approach that has potential application from nanoscale to data-centre-scale computers.This work was supported by the UK Engineering and Physical Sciences Research Council Internet Project EP/H040536/1. This work was supported by the Defense Advanced Research Projects Agency and the Air Force Research Laboratory, under contract FA8750-11-C-0249

Context-driven encrypted multimedia traffic classification on mobile devices

The Internet has been experiencing immense growth in multimedia traffic from mobile devices. The increase in traffic presents many challenges to user-centric networks, network operators, and service providers. Foremost among these challenges is the inability of networks to determine the types of encrypted traffic and thus the level of network service the traffic needs to maintain an acceptable quality of experience. Therefore, end devices are a natural fit for performing traffic classification since end devices have more contextual information about device usage and traffic. This paper proposes a novel approach that classifies multimedia traffic types produced and consumed on mobile devices. The technique relies on a mobile device’s detection of its multimedia context characterized by its utilization of different media input/output (I/O) components, e.g., camera, microphone, and speaker. We develop an algorithm, MediaSense, which senses the states of multiple I/O components and identifies the specific multimedia context of a mobile device in real-time. We demonstrate that MediaSense classifies encrypted multimedia traffic in real-time as accurately as deep learning approaches and with even better generalizability.Peer reviewe