A Comprehensive Analysis of Swarming-based Live Streaming to Leverage Client Heterogeneity

Due to missing IP multicast support on an Internet scale, over-the-top media streams are delivered with the help of overlays as used by content delivery networks and their peer-to-peer (P2P) extensions. In this context, mesh/pull-based swarming plays an important role either as pure streaming approach or in combination with tree/push mechanisms. However, the impact of realistic client populations with heterogeneous resources is not yet fully understood. In this technical report, we contribute to closing this gap by mathematically analysing the most basic scheduling mechanisms latest deadline first (LDF) and earliest deadline first (EDF) in a continuous time Markov chain framework and combining them into a simple, yet powerful, mixed strategy to leverage inherent differences in client resources. The main contributions are twofold: (1) a mathematical framework for swarming on random graphs is proposed with a focus on LDF and EDF strategies in heterogeneous scenarios; (2) a mixed strategy, named SchedMix, is proposed that leverages peer heterogeneity. The proposed strategy, SchedMix is shown to outperform the other two strategies using different abstractions: a mean-field theoretic analysis of buffer probabilities, simulations of a stochastic model on random graphs, and a full-stack implementation of a P2P streaming system.Comment: Technical report and supplementary material to http://ieeexplore.ieee.org/document/7497234

Wooster Magazine: Winter 2012

This edition of the Wooster Magazine was published in the Winter of 2012. Students in Professor Mangubi\u27s printmaking class last semester created very large prints with the help of a 12 ton steamroller. The college has a new core message to deliver, America\u27s premier college for mentored undergraduate research. Recent books published by alumni are on page six. The Communication Sciences and Disorders major is featured from page eight to nineteen. The next section highlights alumni and current students/faculty working with sculpture as their art medium of choice. Annie B Irish was Wooster\u27s first female faculty member and PhD recipient, her legacy is recalled from page 29 to 35.https://openworks.wooster.edu/wooalumnimag_2011-present/1023/thumbnail.jp

Offloading SCION Packet Forwarding to XDP BPF

Existing fixed-function packet processing hardware does not support novel protocols like the next-generation Internet architecture SCION. While SCION routers have previously been accelerated using DPDK and Tofino ASICs, we present an alternative lightweight but feature-complete approach based on the eXpress data path (XDP). We discuss implementation challenges and opportunities unique to the XDP BPF environment and demonstrate a first prototype capable of forwarding at least 0.676 million packets per second per CPU core

Behind the NAT – A Measurement Based Evaluation of Cellular Service Quality

Abstract—Mobile applications such as VoIP, (live) gaming, or video streaming have diverse QoS requirements ranging from low delay to high throughput. The optimization of the network quality experienced by end-users requires detailed knowledge of the expected network performance. Also, the achieved service quality is affected by a number of factors, including network operator and available technologies. However, most studies focusing on measuring the cellular network do not consider the performance implications of network configuration and management. To this end, this paper reports about an extensive data set of cellular network measurements, focused on analyzing root causes of mobile network performance variability. Measurements conducted over four weeks in a 4G cellular network in Germany show that management and configuration decisions have a substantial impact on the performance. Specifically, it is observed that the association of mobile devices to a Point of Presence (PoP) within the operator’s network can influence the end-to-end RTT by a large extent. Given the collected data a model predicting the PoP assignment and its resulting RTT leveraging Markov Chain and machine learning approaches is developed. RTT increases of 58% to 73% compared to the optimum performance are observed in more than 57% of the measurements

Telecommunication Economics — Summary on the Dagstuhl Perspectives Seminar No. 08043

The telecommunications sector and the Internet section of Internet Service Providers (ISP) have become a dynamic key area for the economic development of industrialized nations in the world. It is in constant evolution. Because of intense competition, telecommunications companies and ISPs are forced to diversify their offers and thus to propose an increasing number of services. However, economic analysis often ignores important technical aspects of telecommunications and is not aware of new developments. Engineering models often ignore economic factors. Thus, the design and deployment of future networks that incorporate new services are subject to uncertainties such as equipment and capacity prices (due to technological innovation), demand and supply for services (due to competition). Seeing leading researchers bringing together with various backgrounds, all working on innovative aspects of technical, techno-economic, social, and regulatory issues, lead to the following four main areas that have been partially tackled in an integrated manner: Architectural side, Social side, Economic and business side, and Regulatory side

Flexible Traffic Management in Broadband Access Networks using Software Defined Networking

Abstract-Over the years, the demand for high bandwidth services, such as live and on-demand video streaming, steadily increased. The adequate provisioning of such services is challenging and requires complex network management mechanisms to be implemented by Internet service providers (ISPs). In current broadband network architectures, the traffic of subscribers is tunneled through a single aggregation point, independent of the different service types it belongs to. While having a single aggregation point eases the management of subscribers for the ISP, it implies huge bandwidth requirements for the aggregation point and potentially high end-to-end latency for subscribers. An alternative would be a distributed subscriber management, adding more complexity to the management itself. In this paper, a new traffic management architecture is proposed that uses the concept of Software Defined Networking (SDN) to extend the existing Ethernet-based broadband network architecture, enabling a more efficient traffic management for an ISP. By using SDN-enabled home gateways, the ISP can configure traffic flows more dynamically, optimizing throughput in the network, especially for bandwidth-intensive services. Furthermore, a proofof-concept implementation of the approach is presented to show the general feasibility and study configuration tradeoffs. Analytic considerations and testbed measurements show that the approach scales well with an increasing number of subscriber sessions

Early Work: Path Selection in a Path-aware Network Architecture

Modern path-aware networking (PAN) architectures based on packet-carried forwarding state (PCFS) promise to support practical multipath communication with increased availability and redundancy, even for single-homed hosts. How exactly hosts can chose paths in a meaningful way while maintaining good network utilization as well as user satisfaction is the subject of this research. We demonstrate how overall network utilization is affected by the introduction of multipath communication and propose the term “Cost of Multipath” to reason about this observation. We also identify a collection of concrete practical techniques from networking research and engineering that can be adapted to allow hosts to make more informed path decisions. These tie into the practical implementation of an experimental path-selection engine with a high-level API that we aim to utilize to quantitatively investigate host-based approaches for traffic optimization in the existing path-aware SCION network architectur

Demonstration of the CompactPSH Incentive Scheme in a Peer-to-Peer Streaming Application

This demo shows the CompactPSH incentive scheme integrated in LiveShift. LiveShift is a peer-to-peer video streaming application, which supports both live streaming and video-on-demand. Peers participate in a distributed storage, which adds the ability to replay time-shifted streams from other peers in a distributed manner. The incentive scheme is in place to encourage peers to provide stored video data. CompactPSH allows peers to establish direct and indirect reciprocity to determine the contribution of peers. Thus, non-cooperative peers get a lower video quality than cooperative peers

Towards SCION-enabled IXPs: The SCION Peering Coordinator

Internet eXchange Points (IXPs) around the world bring thousands of ISPs together to form dense peering fabrics. Since bilateral BGP peering sessions alone would result in large overhead, many IXPs offer route servers enabling the exchange of routing information with the entire peering population over a single multilateral BGP session. Route servers also perform RPKI validation to combat the lack of authentication and security in BGP. SCION is a novel inter-domain routing architecture addressing the security flaws of BGP by replacing it with a security and reliability centric clean-slate approach. We envision that operators of SCION ASes will be just as open to peering at Internet exchanges as they are today with BGP. Moreover, to fully utilize SCION's multipath capabilities SCION AS operators tend to deploy more different AS numbers than in BGP, further increasing the potential number of unique peering links at an IX. Since SCION has no native multilateral peering support, we propose the SCION peering coordinator, an IXP-hosted service automating SCION peering link setup based on per AS policies. As such, the SCION peering coordinator provides an open peering platform similar to BGP route servers to SCION