Research group Prof. Zitterbart - Institute of Telematics
Decentralized Bootstrapping of P2P Systems: A Practical View
Author: O. Waldhorst, O. Waldhorst, J. Dinger links:
Source: Proc. 8th IFIP TC6 Int. Conf. on Networking, pp. 703-715, Aachen, Aachen, May 2009
Bootstrapping constitutes the only centralized task in otherwise decentralized P2P systems. As a contribution to the development of generally applicable decentralized bootstrapping mechanisms, in this paper we analyze two decentralized mechanisms approaches from a practical point of view. We consider local host caches and random address probing for bootstrapping into the BitTorrent DHT as an example for a widely deployed P2P system. Based on the results of an extensive measurement study we show that local host caches allow rejoining the P2P system quickly after short times of disconnection, but are impracticable for infrequent or first-time users. Furthermore, random address probing is feasible in a laboratory setting, but is subject to practical issues raised by typical NAT routers and the distribution of ports used by BitTorrent clients. We propose two mechanisms for increasing the performance of random address probing: (1) probing multiple ports per host and (2) hash-based filter-resistant port selection.