This paper presents a detailed characterisation of user behaviour for a series of interactive video experiments over a 12 month period, in which we served popular sporting and musical content. In addition to generic VCR-like features, our custom-built Video-on-Demand application provides advanced interactivity features such as bookmarking. The dramatic impact of such functionality on how users consume content is studied and analysed. We discuss in detail how this user behaviour can be exploited by content distributors to improve user experience. Specifically, we study how simple dynamic bookmark placement and interactivity-aware content pre-fetching and replication can reduce the impact of highly interactive media on CDN performance.

Most existing DHT algorithms assume that all nodes have equal capabilities. This assumption has previously been shown to be untrue in real deployments, where the heterogeneity of nodes can actually have a detrimental effect upon performance. In this paper, we acknowledge that nodes on the same overlay may also differ in terms of their trustworthiness. However, implementing and enforcing security policies in a network where all nodes are treated equally is a non-trivial task. We therefore extend our previous work on Stealth DHTs to consider the differentiation of nodes based on their trustworthiness rather than their capabilities alone.

We propose several models based on discrete-

Abstract

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Most existing DHT algorithms assume that all nodes have equal capabilities. This assumption has previously been shown to be untrue in real deployments, where the heterogeneity of nodes can actually have a detrimental effect upon performance. We now acknowledge that nodes on the same overlay may also differ in terms of their trustworthiness. However, implementing and enforcing security policies in a network where all nodes are treated equally is a non-trivial task. We therefore extend our previous work on Stealth DHTs to consider the differentiation of nodes based on their trustworthiness rather than their capabilities alone.

The infrastructure of the modern Internet has become a complex mesh of varying network types. A single network protocol cannot optimally support every underlying technology and the diverse nature of these networks places increasing strain on the concept of running IP over everything and everything over IP. The introduction of new protocols and services also forces network administrators to employ techniques such as tunneling to ensure end-to-end IP connectivity. Unfortunately these techniques inherently require some form of efficiency trade-off and are not an ideal long term solution.To address these issues, this paper proposes a new network layer protocol, NP++, which uses a level of indirection between the logical and physical specifications of the protocol. NP++ also enables the protocol to automatically configure which physical mapping is used over a link with no direct input from the user. This allows the protocol to change its transmission characteristics depending on the type of underlying network while presenting a unified view to the upper layers. This ensures a higher level of flexibility along with the potential to increase efficiency. The implementation of the NP++ prototype is also demonstrated with a view to encouraging its use when researching next generation Internet technologies.

With the advent of numerous video distribution services, Content Distribution Networks (CDNs) are under increasing demand. Given the associated expenses, many organisations have made use of Peer-to-Peer (P2P) approaches to offset bandwidth costs. Unfortunately, using clients as part of the delivery process can vastly increase load on service providers' networks. Furthermore, many approaches thus far lack the ability for interactive, on-demand viewing. For these reasons, this paper considers how 'hybrid' methods could alleviate these issues, through simulations of delivery methodologies in a CDN context. As it is unlikely that any one method will suffice for all content, network and audience types, a successful system should adapt in response to changes, as outlined in this paper.