Marco Tomsu

A survey of research on the application-layer traffic optimization problem and the need for layer cooperation

A significant part of Internet traffic today is generated by peer-to-peer applications, used traditionally for file sharing, and more recently for real-time communications and live media streaming. Such applications discover a route to each other through an overlay network with little knowledge of the underlying network topology. As a result, they may choose peers based on information deduced from empirical measurements, which can lead to suboptimal choices. We refer to this as the application layer traffic optimization (ALTO) problem and present a survey of existing literature. We summarize and compare existing approaches, identify open research issues, and state the need for layer cooperation as a solution to the ALTO problem.

Scalable spatial information discovery over Distributed Hash Tables

In this paper, we present a Peer-to-Peer (P2P) spatial information discovery system that enables spatial range queries over Distributed Hash Tables (DHTs). Our system utilizes a less-distorting octahedral map projection in contrast to the quadrilateral projections used by majority of the previously proposed systems, to represent the spatial information. We also introduce a Space-Filling Curve (SFC)-based data placement strategy that reduces the probability of data hot-spots in the network. Moreover, we show that our system achieves scalable resolution of location-based range queries, by utilizing a tree-based query optimization algorithm. Compared to the basic query resolution algorithm, the query optimization algorithm reduces the average number of parallel messages used to resolve a query, by a factor of 96%.

Enhancing the Serviceability and the Availability of IMS-Based Multimedia Services: Avoiding Core Service Failures

The delivery of a highly available and robust service offering is one of the critical objectives of service providers. Reaching this objective depends on the level of control service providers have on underlying transport infrastructure. Despite current deployment of IMS-based architectures assumes a vertical integration, IMS-based services can be offered without having a control on the underlying IP network. This paper introduces a solution to enhance the robustness of IMS-based architectures without assuming a vertically integrated system. The paper focuses on failures experienced by core service nodes and describes an autonomic solution to allow customers to access to the service during failures. This paper introduces a novel entity called SBC_PROXY which relays messages from peer SBCs (session border controller) to core service platform. An autonomous mode in which all SBCs are involved in the lookup and routing processes is also described. This paper does not make any assumption on the nature of the service which is offered through IMS. Nevertheless, a focus is put on session-based services such as audio/video telephony.

Enhancing the serviceability of IMS-based multimedia services: preventing core service failures

The delivery of highly available and robust service offerings is a critical objective for Service Providers. Despite current deployment of IMS-based architectures assumes a vertical integration, IMS-based services can be offered without having a control on the underlying IP network. This paper introduces a solution to enhance the robustness of IMS-based architectures without assuming a vertically integrated system. The paper focuses on failures experienced by core service nodes and describes an autonomic solution to allow customers access to the service during failures.