In this paper, we conduct extensive simulations to understand the properties of the overlay generated by BitTorrent. We start by analyzing how the overlay properties impact the efficiency of BitTorrent. We focus on the average peer set size (i.e., average number of neighbors), the time for a peer to reach its maximum peer set size, and the diameter of the overlay. In particular, we show that th...

Abs t rac t We define, for an overlay built on top of an ad hoc network, a simple criterion for neighbourhood: two overlay nodes are neighbours if and only if there exists a path between them of at most R hops, and R is called the (overlay) neighbourhood range. A small R may result in a disconnected overlay, while an unnecessarily large R would generate extra control traffic. We are interested ...

We address the problem of optimal routing in overlay networks. An overlay network is constructed by adding new overlay nodes on top of a legacy network. The overlay nodes are capable of implementing any dynamic routing policy, however, the legacy underlay has a fixed, single path routing scheme and uses a simple work-conserving forwarding policy. Moreover, the underlay routes are pre-determined...

我々は,ネットワークオーバレイのアルゴリズム研究基盤として,オーバレイ構築ツールキット Overlay Weaver を開発・配布している.これを用いることで,計算機 1 台上で繰り返し動作試験を 行いながら,少ないコード量で structured オーバレイのアルゴリズムを実装できる.また,アルゴ リズムの差し替え,および,計算機 1台上での数千ノード規模のエミュレーションが可能であるため, アルゴリズム間の公正な比較を行うことができる.同時に,こうして実装したアルゴリズムはそのま ま実ネットワーク上で動作するため,アルゴリズム研究の成果が直接アプリケーションに結び付く. 本ツールキットでは,アルゴリズムの実装を容易なものとするために,各アルゴリズムに共通する ルーティング処理をアルゴリズム実装から分離した.本論文では,この分離を可能とする両者間のイ ンタフェースを提案する.この分...

Multicast is an important communication paradigm, upon which many distribution applications are built, such as video-on-demand, live broadcasting, teleconferencing, large-volume content dissemination, etc. The efforts to support multicast at IP layer, however, have proved to be slow and painful, due to factors such as ISP’s lack of incentives, shortage of address space, difficulty to support re...

Overlay networks have recently emerged as an effective means to provide a flexible, robust, and scalable platform for distributed applications, while leaving the underlying Internet infrastructure unchanged. This work tackles the overlay network design problem considering both centralized and fully distributed approaches. On one hand, we address the centralized overlay network design problem us...

In overlay-based applications, multiple overlay networks are deployed to fulfill different service requirements. A multioverlay environment may exist in which a number of nodes simultaneously participate in the networks. When there are multiple overlay-based applications running over a set of nodes, some of the nodes take extra effort to maintain multi-overlay networks. Therefore, maintaining t...

PlanetLab has been widely used in the networking community to test and deploy user-defined overlays. Serving as a meta testbed to support multiple overlay networks, PlanetLab has significantly lowered the barriers to build new overlays. However, PlanetLab users always face the problem of selecting a set of nodes and interconnecting them to form the desired overlay network. Unfortunately, such a...

Due to overprovisioning of infrastructure nodes in overlay networks, many nodes remain idle at times of low network load. Some of these nodes could be temporary removed from the overlay topology and could then be used for other purposes or alternatively be temporarily shut down, to save energy. In this paper we present several algorithms to select the subset of overlay nodes that should be part...