An Analysis of the Skype Peer-to-Peer Internet Telephony Protocol

Skype is a peer-to-peer VoIP client developed by KaZaa in 2003. Skype claims that it can work almost seamlessly across NATs and firewalls and has better voice quality than the MSN and Yahoo IM applications. It encrypts calls end-to-end, and stores user information in a decentralized fashion. Skype also supports instant messaging and conferencing. This report analyzes key Skype functions such as login, NAT and firewall traversal, call establishment, media transfer, codecs, and conferencing under three different network setups. Analysis is performed by careful study of Skype network traffic

An experimental study of client-side Spotify peering behaviour

Spotify is a popular music-streaming service which has seen widespread use across Europe. While Spotify’s server-side behaviour has previously been studied, little is known about the client-side behaviour. In this paper, we describe an experimental study where we collect packet headers for Spotify traffic over multiple 24-hour time frames at a client host. Two distinct types of behaviour are observed, when tracks are being downloaded, and when the client is only serving requests from other peers. We also note wide variation in connection lifetimes, as seen in other studies of peer-to-peer systems. These findings are relevant for improving Spotify itself, and for the designers of other hybrid peer-to-peer and server-based distribution architectures

Implementation of Voice Over Internet Protocol (VoIP) in UUM Campus

Currently, users (student, staff and lecturer) at UUM still using traditional mechanism to contact with each other using phone call and messenger contact. In this case, the uses need to have an Internet access in order to communicate with the other side. In both cases, using phone call or Internet has some limitations in terms of cost. This paper proposes the Voice over Internet Protocol (VoIP) system that can help users at UUM campus to freely communicate by using this VoIP technique. In the other side, this proposed system also helps to increase the effectiveness of using the Internet bandwidth; since the users can communicate with each other without the need to have an Internet access. Instead, they can contact with each other using the current Local Area Network (LAN) at UUM. Thus, this system can let the users to contact the destination user anywhere anytime in the coverage area of UUM

Analyzing of MOS and Codec Selection for Voice over IP Technology

In this research, we propose an architectural solution to implement the voice over IP (VoIP) service in campus environment network. Voice over IP (VoIP) technology has become a discussion issue for this time being. Today, the deployment of this technology on an organization truly can give a great financial benefit over traditional telephony. Therefore, this study is to analyze the VoIP Codec selection and investigate the Mean Opinion Score (MOS) performance areas evolved with the quality of service delivered by soft phone and IP phone. This study focuses on quality of voice prediction such as i) accuracy of MOS between automated system and human perception and ii) different types of codec performance measurement via human perception using MOS technique. In this study, network management system (NMS) is used to monitor and capture the performance of VoIP in campus environment. In addition, the most apparent of implementing soft phone and IP phone in campus environment is to define the best codec selection that can be used in operational environment. Based on the finding result, the MOS measurement through automated and manual system is able to predict and evaluate VoIP performance. In addition, based on manual MOS measurement, VoIP conversations over LAN contribute more reliability and availability performance compare to WAN.Comment: 14 pages, exposed on 5th International Conference "Actualities and Perspectives on Hardware and Software" - APHS2009, Timisoara, Romani

Secure communication using dynamic VPN provisioning in an Inter-Cloud environment

Most of the current cloud computing platforms offer Infrastructure as a Service (IaaS) model, which aims to provision basic virtualised computing resources as on-demand and dynamic services. Nevertheless, a single cloud does not have limitless resources to offer to its users, hence the notion of an Inter-Cloud enviroment where a cloud can use the infrastructure resources of other clouds. However, there is no common framework in existence that allows the srevice owners to seamlessly provision even some basic services across multiple cloud service providers, albeit not due to any inherent incompatibility or proprietary nature of the foundation technologies on which these cloud platforms are built. In this paper we present a novel solution which aims to cover a gap in a subsection of this problem domain. Our solution offer a security architecture that enables service owners to provision a dynamic and service-oriented secure virtual private network on top of multiple cloud IaaS providers. It does this by leveraging the scalability, robustness and flexibility of peer- to-peer overlay techniques to eliminate the manual configuration, key management and peer churn problems encountered in setting up the secure communication channels dynamically, between different components of a typical service that is deployed on multiple clouds. We present the implementation details of our solution as well as experimental results carried out on two commercial clouds

Evidences Behind Skype Outage

Skype is one of the most successful VoIP application in the current Internet spectrum. One of the most peculiar characteristics of Skype is that it relies on a P2P infrastructure for the exchange of signaling information amongst active peers. During August 2007, an unexpected outage hit the Skype overlay, yielding to a service blackout that lasted for more than two days: this paper aims at throwing light to this event. Leveraging on the use of an accurate Skype classification engine, we carry on an experimental study of Skype signaling during the outage. In particular, we focus on the signaling traffic before, during and after the outage, in the attempt to quantify interesting properties of the event. While it is very difficult to gather clear insights concerning the root causes of the breakdown itself, the collected measurement allow nevertheless to quantify several interesting aspects of the outage: for instance, measurements show that the outage caused, on average, a 3-fold increase of signaling traffic and a 10-fold increase of number of contacted peers, topping to more than 11 million connections for the most active node in our network - which immediately gives the feeling of the extent of the phenomeno

Preliminary thoughts on services without servers

Warehouse-scale computing supports cloud-based services such as shared disk space, computation services and social networks. Although warehouse-scale computing is inexpensive per user, the cost to entry is high, and the pressures to generate revenues to cover costs leads service providers to pursue monetizing services aggressively. In this paper, we explore some ideas for removing the need for central servers by exploiting peer-to-peer technologies

A Empirically Validated Framework for Limiting Free-Riding in P2P Networks through the Use of Social Network Information

In order to overcome the problem of free-riding in current P2P system, we suggest applying social network theory. Based on our exploration of the overlapping research fields of social networks and peer-to-peer networks, we propose a new P2P framework within this paper. It specifies social network information that can be used in a P2P system to avoid performance inefficiencies caused by free-riding or by policies to overcome free-riding. To identify this specific social network information, we conduct a survey among a small group of students, who use Skype, a popular P2P system. We use descriptive analysis and multiple regression analysis to analyze the survey data. The results of the analyses provide an indication that the idea of using social network information in P2P systems is valid and that it is supported by P2P users. Based on our findings, we make recommendations for a successful implementation of social-network-information-based P2P systems that can overcome free-riding issues and, consequently, improve the performance of P2P systems

Benefits on using H-P2PSIP in mobile environments

Proceeding of: VIII Jornadas de Ingeniería Telemática (JITEL '09), Universidad Politécnica de Cartagena, Cartagena, Murcia, 15-17 de septiembre de 2009The use of peer-to-peer technologies is increasing everyday and the improvement of mobility technologies is a reality. Now, it is expected that peer-to-peer applications run on mobile devices, but the conjunction of these two technologies is an open research issue. The user mobility impacts on the churn suffered by peer-to-peer networks and consequently it impacts on their performance. Therefore, some mechanisms are necessary to minimize this undesirable effect. Our proposal tries to solve this problem by using a Hierarchical P2PSIP architecture where different overlays are used for different peer mobility behaviours and they are interconnected between them through an interconnection overlay. In this way it is possible for peers that share the same behaviour to choose a certain protocol or to optimize some functionality that suits best with their mobility situation, while maintaining connectivity with all peers.This research work is being supported by the European Commission under the IST Content Network of Excellence3 (FP6-2006-IST-038423), by the Regional Government of Madrid under the BioGridNet4 project (CAM, S-0505/TIC- 0101) and by the Ministry of Science and Innovation under the CONPARTE project (MEC, TEC2007-67966-C03-03/TCM).No publicad