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A Proposal of Request Routing on a Fully Distributed P2P CDN
Yasushi ICHIKAWA Takashi TOMIMOTO Toshihiko SHIMOKAWA Yuko MURAYAMA
IEICE TRANSACTIONS on Communications
Publication Date: 2005/06/01
Print ISSN: 0916-8516
Type of Manuscript: PAPER
peer-to-peer, CDN, Internet, P2P CDN, application level multicast,
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A peer-to-peer (P2P) Contents Delivery Network (CDN) is a system in which the users get together to forward contents so that the load at a server is reduced. Lately, we have high-speed services for an access to the Internet such as the Asymmetric Digital Subscriber Line (ADSL). Some broadcasters may not have such services because they have only dial-up services and wireless services as PHS and a mobile phone to broadcast live. A problem with P2P CDN is its overhead to construct a distribution tree. It becomes a crucial problem when a broadcaster has only a low-speed access to the Internet, and we propose a P2P CDN system which reduces such an overhead. A server peer is the root peer of a distribution tree and provides users with contents. With the existing algorithms, new peers measure a Round Trip Time (RTT) and a throughput from a broadcaster site when they join the distribution tree. With our algorithm, a new peer sends the server peer a Search Request message which is forwarded throughout the distribution tree until a suitable peer which has enough bandwidth to accomodate is found finally so that the new peer will measure a throughput to that peer. The problem with our algorithm is that as the number of users in the tree increases, the new peer will be preoccupied with measurement, because it may find many suitable peers as its parent candidates. To solve this problem, we introduce a Time To Stop Broadcast (TTSB) on the Search Request message in order to reduce the number of measurement. We have compared the traditional algorithm with ours by simulation. From the simulation results, we have found that our method is effective when a server peer has a low-speed access to the Internet, while the users have a high-speed access.