University of Wollongong Research Online Faculty of Engineering and Information Faculty of Informatics - Papers (Archive) Sciences 30-11-2005 BitTorrent in a dynamic resource adapting peer-to-peer network L. Rong University of Wollongong I. Burnett University of Wollongong, [email protected] Follow this and additional works at: https://ro.uow.edu.au/infopapers Part of the Physical Sciences and Mathematics Commons Recommended Citation Rong, L. and Burnett, I.: BitTorrent in a dynamic resource adapting peer-to-peer network 2005. https://ro.uow.edu.au/infopapers/264 Research Online is the open access institutional repository for the University of Wollongong. For further information contact the UOW Library: [email protected] BitTorrent in a dynamic resource adapting peer-to-peer network Abstract Our previous work proposed a MPEG-21 based P2P network architecture supporting resource adaptation on the basis of usage environment and user preferences. In this paper, we investigate the deployment of a BitTorrent (BT) - like approach in the previous super-peer P2P resource adaptation architecture. In addition, the architecture's peer selection strategy is adopted and evaluated as a way to enhance the peer selection process in BT. The strategy uses super peers as trackers to intelligently select peers according to their capabilities and shared resource segments. Simulation results show that the proposed selection strategy reduces average access time and increases download speed when compared with the existing BT peer selection process with randomly selected peers. The results also show that the deployment of BT in the P2P adaptation architecture greatly reduces the congested download problem previously reported. Disciplines Physical Sciences and Mathematics Publication Details This article was originally published as: Rong, L & Burnett, I, BitTorrent in a dynamic resource adapting peer-to-peer network, AXMEDIS 2005, First International Conference on Automated Production of Cross Media Content for Multi-Channel Distribution, 30 November-2 December 2005, 4 pp. Copyright IEEE 2005. This conference paper is available at Research Online: https://ro.uow.edu.au/infopapers/264 BitTorrent in a Dynamic Resource Adapting Peer-to-Peer Network Letian Rong, Ian Burnett TITR, University of Wollongong, Australia1 [email protected], [email protected] Abstract [1] proposes a simple greedy scheme that selects serv- ing peers based on their uploading session status and Our previous work proposed a MPEG-21 based uplink bandwidth. Adler et al. [2] investigates the P2P network architecture supporting resource adapta- scenarios of serving peer selection in a parallel tion on the basis of usage environment and user pref- downloading or streaming P2P environment, and pro- erences. In this paper, we investigate the deployment posed use of micro-payments as the solution to the of a BitTorrent (BT) - like approach in the previous peer selection process. super-peer P2P resource adaptation architecture. In However, these projects focus on pure P2P net- addition, the architecture’s peer selection strategy is works where peers are interconnected and functioning adopted and evaluated as a way to enhance the peer without any central entities; requesting peers must selection process in BT. The strategy uses super peers thus select serving peers themselves. Our work is fo- as trackers to intelligently select peers according to cused on hybrid P2P [4], such as BT, where a central their capabilities and shared resource segments. entity (i.e., tracker or super peer) is used to perform Simulation results show that the proposed selection some of the tasks. Currently, the only project that ad- strategy reduces average access time and increases dresses peer selection in a hybrid P2P network is the download speed when compared with the existing BT work from Koo et al. [3] which uses a genetic- peer selection process with randomly selected peers. algorithm-based optimization to maximize the overall The results also show that the deployment of BT in the disjointedness of content among serving peers in the P2P Adaptation architecture greatly reduces the con- network. However, there are several limitations to gested download problem previously reported. their contribution: 1. A global optimization based approach is used to 1. Introduction determine peer selections in the network. However, the approach selects serving peers for each Recently, a new generation of P2P applications has downloading peer based on the assumption that all been gaining popularity for the download of large- peers start downloading at the same time. It then sized content such as multimedia resources. In these calculates the optimal solution for the whole net- P2P applications, resources are divided into small work. This is impractical as in real life situations, segments such that peers can exchange these segment peers make requests at different times and also pieces instead of the complete resource. Also a number some peers are always idling. of central entities – “trackers” are used to select a list 2. A single tracker is deployed in the network to store of resource senders that can fulfill a request from a all peer information and perform peer selections. peer. The most successful application in this category This is unrealistic and not scalable to a large P2P is BitTorrent (BT) [5]. In this paper, we investigate network. the feasibility of deploying BT based solutions in a 3. The ‘total number of bytes downloaded so far’ is dynamic resource adapting P2P environment using our the only attribute used to calculate the peer selec- previously proposed super peer based architecture [6]. tions. Other important attributes should be consid- The work shows that there are significant benefits to ered in the selection process (i.e., bandwidth, ter- using a combined super-peer / BT peer selection strat- minal capabilities). egy. The work reported in the current paper addresses these deficiencies using several improvements to our 2. Related work and motivation previously proposed dynamic resource adapting P2P P2P based peer selection strategy has been the topic architecture. of various research projects. For instance, Zou et al. 1. This work is funded by the Smart Internet Technology CRC. Proceedings of the First International Conference on Automated Production of Cross Media Content for Multi-Channel Distribution (AXMEDIS’05) 0-7695-2348-X/05 $20.00 © 2005 IEEE 3. Dynamic resource adaptation P2P sys- existing P2P architecture [8] by using the super peers tem with BitTorrent in the network as trackers. Therefore each time when a peer requests a resource, it contacts its locality clus- In our previously proposed dynamic resource adap- ter super peer which selects a list of peers from the tation P2P architecture [6], peers were grouped into cluster to exchange resource segments with the re- clusters based on similarity of their shared contents questing peer. and super peers were nominated to be in charge of one The advantage of this approach is that, in the pro- or more clusters. On joining the network, a peer must posed architecture, super peers store registered peer submit information about its shared resources and its information for their locality clusters and select the related usage environment attributes (i.e., terminal appropriate resource senders for their peers. Thus, the capabilities) to the super peer(s). Super peers then use incorporation of trackers upgrades the role of the su- the registered information to adapt search results and per peer to select multiple resource senders for each resources for requesting peers. request and this is a minimal modification to the The proposed architecture was then further im- current infrastructure detailed in [8]. proved through a locality-based clustering approach The tracker selection strategy is performed in three which assigns peers to clusters on the basis of their steps: locality information [8]. By default, the approach re- Step1: A peer sends a resource request to its local- quires new peers to register to locality-based super ity super peer, which searches through the locality peers but also allows them to be registered to category cluster to return a list of peers with higher or equal super peers (i.e., super peers who govern one particu- capabilities than the requesting peer. We assume that lar type of content) based on their shared content. The peers store resource variations based on their capabili- architecture, however, was designed to facilitate only ties. This means that resource variations from a cer- one-to-one resource transfer between peers. This is not tain peer class can only be consumed by peers of that scalable to the download of large size resources with class (i.e., similar terminal capabilities) and obtained limited available copies, as downloads could be con- from peers of equal or higher classes (i.e., higher ter- gested if there are too many requests at the same time. minal capabilities). If a resource is transferred from a Therefore, we now incorporate a BT based resource higher class to a lower class peer, it is dynamically exchange method into the architecture; this allows adapted during the process. peers to download/upload resource segments from Step2: Next, the initially filtered peers are sepa- multiple peers. rated into various class groups according to the num- The new architecture improves upon the standard ber of different peer classes within the returned peer BT approach by taking advantage of the existing dy- list.