CLOSER: A Collaborative Locality-aware Overlay SERvice

Current Peer-to-Peer (P2P) file sharing systems make use of a considerable percentage of Internet Service Providers (ISPs) bandwidth. This paper presents the Collaborative Locality-aware Overlay SERvice (CLOSER), an architecture that aims at lessening the usage of expensive international links by exploiting traffic locality (i.e., a resource is downloaded from the inside of the ISP whenever possible). The paper proves the effectiveness of CLOSER by analysis and simulation, also comparing this architecture with existing solutions for traffic locality in P2P systems. While savings on international links can be attractive for ISPs, it is necessary to offer some features that can be of interest for users to favor a wide adoption of the application. For this reason, CLOSER also introduces a privacy module that may arouse the users' interest and encourage them to switch to the new architectur

A Tunnel-aware Language for Network Packet Filtering

Abstract—While in computer networks the number of possible protocol encapsulations is growing day after day, network administrators face ever increasing difficulties in selecting accurately the traffic they need to inspect. This is mainly caused by the limited number of encapsulations supported by currently available tools and the difficulty to exactly specify which packets have to be analyzed, especially in presence of tunneled traffic. This paper presents a novel packet processing language that, besides Boolean filtering predicates, introduces special constructs for handling the more complex situations of tunneled and stacked encapsulations, giving the user a finer control over the semantics of a filtering expression. Even though this language is principally focused on packet filters, it is designed to support other advanced packet processing mechanisms such as traffic classification and field extraction. I

Distributed connectivity service for a SIP infrastructure

Because of the constant reduction of available public network addresses and the necessity to secure networks, middleboxes such as network address translators and firewalls have become quite common. Because they are designed around the client-server paradigm, they break connectivity when protocols based on different paradigms are used (e.g., VoIP or P2P applications). Centralized solutions for middlebox traversal are not an optimal choice because they introduce bottlenecks and single point-of-failures. To overcome these issues, this article presents a distributed connectivity service solution that integrates relay functionality directly in user nodes. Although the article focuses on applications using the Session Initialization Protocol, the proposed solution is general and can be extended to other application scenario

Design and implementation of locality-aware P2P system

One of the most relevant problem for an Internet Service Provider is the large bandwidth usage on international links, mainly due to peer-to-peer applications adopted for file-sharing. The Collaborative Locality-aware Overlay SERvice (CLOSER) technology has been recently proposed to solve this issue by properly modifying the behavior of peer-to-peer application. The technology is also covered in two recent patent applications. This paper presents possible design guidelines to actually implement CLOSER in a DHT-based peer-to-peer system and describe a real implementation based on the popular aMule applicatio

A LOTOS Extension for the Performance Analysis of Distributed Systems

Performance analysis and formal correctness verification of computer communication protocols and distributed systems have traditionally been considered as two separate fields. However, their integration can be achieved by using formal description techniques as paradigms for the development of performance models. This paper presents a novel extension of LOTOS, one of the two formal specification languages that were standardized by ISO. The extension is specifically conceived to integrate performance analysis and formal verification. The extended language syntax and semantics are formally defined, along with a mapping from extended specifications to performance models, The mapping preserves the specified observable behavior. Two simple examples, a stop-and-wait protocol and a time-sharing system, are used to concretely demonstrate the new approach and to validate i