Showing papers by "Jon Crowcroft published in 1999"

Watercasting: Distributed Watermarking of Multicast Media

Abstract: We outline a scheme by which encrypted multicast audiovisual data may be watermarked by lightweight active network components in the multicast tree. Every recipient receives a slightly different version of the marked data, allowing those who illegally re-sell that data to be traced. Groups of cheating users or multicast routers can also be traced. There is a relationship between the requirements for the scheme proposed here, the requirements for reliable multicast protocols, and proposed mechanisms to support layered delivery of streamed media in the Internet.

Internetworking Multimedia

Abstract: From the Publisher: Increasingly, businesses are turning to Internet-based multimedia communication as a tool to use internally and as the foundation for online services that can be sold to customers. Whether the goal is videoconferencing, distance learning, telemedicine, or real-time entertainment broadcasts, demand for expertise in the underlying technologies is growing rapidly. Internetworked Multimedia offers students, systems engineers, network administrators, and product developers a complete guide to today's approaches to Internetworked multimedia. Combining coverage of technological principles, middleware, and applications, this book prepares technical readers to contribute in a variety of roles, from strategic decision-making to implementation to ongoing administration. Features Written by a team of highly respected authors serving on committees formed to define standards for Internetworked multimedia; covers all the latest protocols for exchanging sound and moving images across the Internet in real time. Addresses topics of special interest to implementers and administrators, such as network service models, security, application support, and problem resolution. Examines issues affecting the user's experience, including session creation, announcement, and invitation, collaboration, and media-on-demand. Combines low-level technical information, a critical assessment of the state of the art, and a keen vision of the medium's potential-in a single up-to-date resource.

A charging model for sessions on the Internet

Abstract: A chargeable session on the Internet may consist of more than one underlying chargeable service. Typically there will be two, one at the network layer and one at the session layer. Since different applications can have different demands from the network, a generic charging scheme has to separate the service provided by the network from the service provided by an application/service provider. In this paper we propose a pricing model which is session-based and we look at the impact of this on real-time multimedia conferencing over the Internet. In this model, we are trying to allow for the optional integration of charging at the network layer with charging at the session layer, while keeping the underlying technologies still cleanly apart. This paper also highlights the fact that the main problem of pricing application on the Internet is not just a simple case of analyzing the most technically feasible pricing mechanism but also making the solution acceptable to users. We take the position that session-based pricing is easier for end users to accept and understand and show why this is the case in this paper.

Application-level Programmable Internetwork Environment

Abstract: Future requirements for a broadband multimedia network are likely to be very different from those today. Three key changes are identified — rapid introduction of new services, dynamic customisation of services by clients, and minimal management overhead. Application-layer active networking, perhaps the most pragmatic and immediately realisable active network proposal, is a potential solution to all three. In the ‘Management of Multiservice Networks‘ project, BT and its academic partners are developing key middleware components required to support application-layer active networking.

A Charging Model for Sessions on the Internet

Abstract: A chargeable session on the Internet may consist of more than one underlying chargeable service. Typically there will be two, one at the network layer and one at the session layer. Since different applications can have different demands from the Network, a generic charging scheme has to separate the service provided by the network from the service provided by an application/service provider. In this paper we propose a pricing model which is session based and we look at the impact of this on real-time multimedia conferencing over the Internet. In this model, we are trying to allow for the optional integration of charging at the network layer with charging at the session layer, while keeping the underlying technologies still cleanly apart. This paper also highlights the fact that the main problem of pricing application on the Internet is not just a simple case of analyzing the most technically feasible pricing mechanism but also making the solution acceptable to users. We take the position that session based pricing is easier for end users to accept and understand and show why this is the case in this paper.

Architecture of conference control functions

Abstract: Conference control is an integral part in many-to-many communications that is used to manage and co-ordinate multiple users in conferences. There are different types of conferences which require different types of control. Some of the features of conference control may be user invoked while others are for internal management of a conference. In recent years, ITU (International Telecommunication Union) and IETF (Internet Engineering Task Force) have standardized two main models of conferencing, each system providing a set of conference control functionalities that are not easily provided in the other one. This paper analyzes the main activities appropriate for different types of conferences and presents an architecture for conference control called GCCP (Generic Conference Control Protocol). GCCP interworks different types of conferencing and provides a set of conference control functions that can be invoked by users directly. As an example of interworking, interoperation of IETF's SIP and ITU's H.323 call control functions have been examined here. This paper shows that a careful analysis of a conferencing architecture can provide a set of control functions essential for any group communication model that can be extensible if needed.

CRAM: Cell Re-labeling At Merge-points for ATM multicast

Abstract: Many distributed multimedia applications involve data delivery from a source to multiple destinations, the participating nodes forming a multicast group. In the naive solution, separate connections can be established from each source to other group members. However, a tree can be established for each source with the participants as the leaf nodes or just have one tree spanning all the participants. In this paper, we introduce a data forwarding model to support such shared multicast trees over the ATM networks called CRAM (Cell Re-labeling At Merge-points for ATM multicast). Our work allows VC merging in the MPLS architecture and supports recently proposed wide area multicast protocols (like CBT and PIM) in ATM networks.

Components for distributed virtual environments

Abstract: The majority of existing systems supporting Large Scale Virtual Environments (LSVE) are based on monolithic architectures, making maintenance, reusability and extensibility difficult at best. An overview of the Java Adaptive Dynamic Environment (JADE) is presented as an alternative to the traditional approach for developing a core infrastructure for VE systems. JADE consists of a light-weight cross-platform kernel with inherent capabilities for dynamic extensibility in run-time. Although the design principles are applicable to other areas, the implementation is targeted at LSVE. The JADE implementation is 100% Java, taking full advantage of the following properties: wide deployment across major operating systems and browsers; comprehensive set of packages; networking capabilities and security mechanisms.

IP over photons: how not to waste the waist of the hourglass

Abstract: IP is often referred to as the waist of the hourglass, because of the simple model the Internet provides packet level communication compared to other approaches (eg, FR, X25 or B-ISDN), but runs over a complex plethora of links and switched networks, and is used by a firmament of application and transport protocols The ever increasing demand for capacity is pushing us past the 40 Gbit/s barrier, and towards the terabit link Dense mode WDM offers 128 wavelengths at tens of gigabytes per wavelength However re-tuning takes geological epochs compared to IP packet switching, or flow switching, or even QoS routing time frames The problem resembles that of IP over ATM or other virtual circuits, but this may be misleading: what is needed is a novel approach to a network architecture, that avoids the same design flaws and pitfalls we have been forced into in IP over ATM (including MPLS) This paper briefly describes why these approaches are misled, and attempts to outline an approach based on network edge packet sorting and scheduling, which may allow us to use pure optical core networks without sacrificing the flexibility of what we might call legacy electron-datagram services