Fabio Picconi

Is There a Future for Mesh-Based live Video Streaming?

Peer-to-peer live streaming systems allow a bandwidth-constrained source to broadcast a video feed to a large number of users. In addition, a design with high link utilization can achieve high stream rates, supporting high-quality video. Until now, only tree-based designs have been shown to achieve close-to-optimal rates in real-life conditions, leaving the question open as to the attainable efficiency of completely unstructured mesh-based approaches. In this paper we answer that question by showing that a carefully-designed mesh-based system can achieve close-to-optimal stream rates. Specifically, we implement and evaluate a design based on a mesh-based algorithm called DP/LU. Contrary to tree-based designs, DP/LU uses an unstructured overlay, which is easier to construct and is highly resistant to churn. In addition, we introduce mechanisms for overlay rewiring and source scheduling that lead to significant performance improvements. Our experimental evaluation shows that our design achieves 95% of the maximum achievable stream rate in a static environment, and 90% under high churn. This demonstrates that mesh-based designs are an excellent choice for scalable and robust high-quality peer-to-peer live streaming.

ISP Friend or Foe? Making P2P Live Streaming ISP-Aware

Current peer-to-peer systems are network-agnostic, often generating large volumes of unnecessary inter-ISP traffic. Although recent work has shown the benefits of ISP-awareness on bulk transfer applications, no studies have focused on optimizing P2P live streaming systems. These are harder to design, as data must be diffused to all receivers within short delays. In this paper we propose a novel scheme for ISP-friendly mesh-based live streaming. Each peer maintains two distinct sets of overlay neighbors, used respectively for local and global stream propagation. A dynamic unchoke mechanism minimizes inter-ISP traffic in normal operation, enabling it promptly when local diffusion is impaired, e.g., when fast local sources become suddenly unavailable. Our scheme is independent of the chunk scheduling algorithm, and thus can be applied to a wide range of existing systems. We have integrated our ISP-friendly scheme to our P2P live streaming prototype, and evaluated its performance through emulation and Planetlab experiments. Our results show that our scheme adapts quickly to churn and dynamic network conditions, and achieves up to a ten-fold reduction in transit traffic.

Is there life in Second Life

Social virtual worlds such as Second Life are digital representations of the real world where human-controlled avatars evolve and interact through social activities. Understanding the characteristics of existing virtual worlds can be extremely valuable to optimize their design. In this work we perform the first extensive analysis of Second Life. We have crawled around 13000 Regions over one month, and gathered information about objects, avatars, and server state. The analysis of our traces shows several surprising results. We find that 30% of the Regions are never visited during a six day period, whereas only few Regions have large peak populations. Moreover, the vast majority of Regions are static, i.e., objects are seldom created or destroyed. Interestingly, avatars interact similarly to humans in real life, gathering in small groups, visiting the same places and meeting the same avatars again, showing a highly predictable behavior. Based on these observations, we discuss several techniques to enhance Second Life or other similar social virtual worlds.

Service hosting gateways: a platform for distributed service deployment in end user homes

The success of broadband residential Internet access is changing the way home users consume digital content and services. Currently, each home service requires the installation of a separate physical box (for instance, the NetFlix box or IPTV set-top-boxes). Instead, we argue for deploying a single box in the home that is powerful and flexible enough to host a variety of home services. In addition, this box is managed by the Internet Service provider and is able to provide service guarantees. We call such a box a service-hosting gateway (SHG), as it combines the functionalities of the home gateway managed by the network service provider with the capability of hosting services. Isolation between such services is ensured by virtualization. We demonstrate a prototype of our (SHG). It is based on the hardware platform that will be used for future home gateways. We illustrate the features of the SHG with multiple use cases ranging from simple service deployment scenarios to complex media distribution services and home automation features.