Network hosted transcoding services for optimized delivery of multimedia streams

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Distributed replica placement algorithms for peer-to-peer content distribution networks

Recently there has been an increasing deployment of content distribution networks (CDNs) offering hosting services to Web content providers. CDNs deploy a set of surrogate servers distributed throughout the Internet and replicate provider content across these servers to provide better performance and availability than centralised provider servers do. Problems regarding robustness, scalability, accessibility and efficiency however, brought the attention to peer-to-peer (P2P) architectures for use in CDNs. In P2P architectures, every node acts as a client and as a server. This way, intelligence is spread over the network, making self-organisation and automatic recovery more easy. In this paper, we present several replica placement algorithms (RPAs) for peer-to-peer CDNs. We will show that they enhance CDN performance by determining the optimal location of content replicas on the surrogate servers

An active networking based service for media transcoding in multicast sessions

Active networking is one of the suggested technologies to introduce additional intelligence and programmability in the network and its services. In this paper, the use of active networking to support advanced multicast services providing media transcoding inside the network is investigated. In the multicast service different versions of the streamed data are made available and customers can select a specific version according to their wishes or their capabilities. Based on the active networking facilities of the underlying framework the different versions of the streamed data can be created inside the network, through transformations or transcodings of the original data. Both design and performance issues of the detailed service are discussed. A new multicast tree set-up protocol, taking into account the required transcodings, is introduced. A number of different strategies are discussed optimizing the location of the transcodings as well as the use of bandwidth in the network, while considering the availability of sufficient processing power in the nodes. The performance analvsis is done for a voice stream multicast service, addressing the efficiency of the tree set-up strategies, the optimization of network resource utilization, the use of processing power for transcodings, and the resulting quality of streamed voice signals after multiple transcodings