46_3 - Service Capacity of Peer to Peer Networks Xiangying...

Info iconThis preview shows pages 1–2. Sign up to view the full content.

View Full Document Right Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: Service Capacity of Peer to Peer Networks Xiangying Yang and Gustavo de Veciana Department of Electrical and Computer Engineering The University of Texas at Austin Austin, TX 78712 { yangxy,gustavo } @ece.utexas.edu Abstract — In this paper we study the ‘service capacity’ of peer to peer (P2P) file sharing applications. We begin by considering a transient regime which is key to capturing the ability of such sys- tems to handle bursty traffic, e.g., flash crowds. In this context our models, based on age dependent branching processes, exhibit ex- ponential growth in service capacity, and permit the study of sen- sitivity of this growth to system policies and parameters. Then we consider a model for such systems in steady state and show how the average delay seen by peers would scale in the offered load and rate at which peers exit the system. We find that the average delays scale well in the offered load. In particular the delays are upper bounded by some constant given any offered load and even decrease in the offered load if peers exit the system slowly. We validate many of our findings by analyzing traces obtained from a second generation P2P application called BitTorrent. Index Terms — system design, network measurements, peer to peer applications, flash crowds, service capacity, performance eval- uation, mathematical modeling I. INTRODUCTION Peer-to-peer (P2P) architectures for file sharing among ad hoc, possibly dynamic, collections of hosts are generating an increas- ing fraction of the traffic on today’s Internet and are reshaping the way new network applications are designed. The idea is to have hosts participate in an application level overlay network enabling signaling, routing, and searching among participating hosts. Once a host locates the document(s) of interest, direct connections are established to mediate their transfer. The key principle is to allow, and in fact encourage, participating hosts to play dual roles as servers and clients – thus hosts are considered peers. P2P file sharing applications first became prominent with the introduction of Napster, which allowed users to share MP3 for- matted music files. In February 2001, Napster boasted a peak of 1.5 million simultaneous users[1], but subsequently suffered legal setbacks. However new P2P file sharing applications such as Gnutella, KaZaA, Morpheus, eDonkey and BitTorrent con- tinue emerging and the number of users is growing faster than ever[2]. Indeed, in March 2002 2.9 million simultaneous online users were reported [3], and 6.2 million users in January 2003, see http://www.slyck.com . According to the SD–NAP trace [3], the dominant traffic type observed by Internet service providers (ISPs) is associated with P2P file sharing applications. Per- haps driven by the growth in broadband services, e.g., cable and This work is supported in part National Science Foundation Grant ECS- 0225448....
View Full Document

This note was uploaded on 12/08/2011 for the course CS 525 taught by Professor Gupta during the Spring '08 term at University of Illinois, Urbana Champaign.

Page1 / 11

46_3 - Service Capacity of Peer to Peer Networks Xiangying...

This preview shows document pages 1 - 2. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online