John S. Crawford

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— This paper investigates the problem of generating low delay degree-constrained overlay multicast trees for single source real-time applications in a distributed environment. This optimisation problem has been proven to be NP-hard. Traditional distributed solutions often use a greedy approach where on-tree nodes try to get as close as possible to the data(More)
Several multicast routing heuristics have been proposed to support multimedia services, both interactive and distribution, in high speed networks such as B-ISDN/ATM. Since such services may have large numbers of members and have real-time constraints, the objective of the heuristics is to minimise the multicast tree cost while maintaining a bound on delay.(More)
— Application layer multicast (ALM) enables rapid deployment of multicast applications in the Internet. In ALM, application hosts organise themselves into an overlay topology on top of the underlying unicast network. Application data is multicast over the overlay network. In general, ALM protocols can be classified as either tree-first or mesh-first(More)
Conventional delivery mechanisms for many-to-many multicast services consider either a single shared tree or a source rooted trees approach. These two mechanisms complement each other in terms of performance and protocol complexity. In this paper, we describe a design that uses multiple shared trees that would provide a balance between these two extreme(More)
This paper introduces a flexible new method of constructing hierarchical multicast structures suitable for supporting large-scale GRID applications. Hierarchical multicast trees are constructed by repeated application of clustering algorithms that partition the members of a large application community to form a layered hierarchy of clusters of users. The(More)
An increasing number of networking applications involve m ul-tiple participants and are therefore best supported by m ulticasting. Where a m ulticast application consumes high bandwidth, it is important to min-imise the eeect on the network by oering economical multicast routes. Many new applications made possible by n e t works based on ATM involve(More)
Acute and chronic pain resulting from injury, surgery, or disease afflicts >100 million Americans each year, having a severe impact on mood, mental health, and quality of life. The lack of structural and functional information for most ion channels, many of which play key roles in the detection and transmission of noxious stimuli, means that there remain(More)
We are interested in constructing low latency data delivery trees for application layer multicast (ALM). A salient feature of ALM is that it uses an overlay topology built on top of existing unicast services to bypass the need for the network layer multicast support. However, ALM protocol hosts are normally end systems that have constrained access(More)