|
|
|
|
|
|
|
Overlay networks refer to networks working on top of the Internet. Overlay networks enhance or modify the basic functioning of the Internet, improving end-to-end delays and resilience (Resilient Overlay Network), introducing anonymity (Tor, Freenet), enhancing security (VPNs), and efficiently supporting content delivery (Akamai, Digital Island), file sharing (Gnutella, BitTorrent, EMule) or Voice over IP (Skype). While they can provide a way to first experiment new solutions for future Internet architecture and to incrementally deploy them, at the same time they seem to threaten traditional Internet end-to-end paradigm, and current business and management policies. Moreover, overlay networks work at the application layer, and the services are controlled by the end-systems using the Internet infrastructure. This enables potential conflicts among the interests of overlay users and those of Internet service providers or of the whole Internet community. This issue can be profitably addressed using game theory framework. In this talk we show how the loss of efficiency due to user selfishness can be quantified. We first briefly present how some recent theoretical results on routing can be applied to overlay networks for routing, then focus on file sharing networks. We show that the loss of efficiency is in many case unbounded even when some strategies intended to enforce cooperation, like BitTorrent Tit-for-Tat, are applied.
|
|
|
|
|
|
|
|