Showing papers by "Jon Crowcroft published in 1995"

Bandwidth-delay based routing algorithms

Abstract: Multimedia applications often require guaranteed quality of service and resource reservation, which has raised a number of challenging technical issues for routing. We consider two new routing algorithms based on bandwidth and delay metrics. The implications of routing metrics on path computation are examined and the rationales behind the selection of bandwidth and delay metrics are discussed. Two new routing algorithms based on bandwidth and delay metrics are presented and some of their important properties are investigated.

Multicast-specific security threats and counter-measures

Abstract: Security issues in multicast communication have rarely been touched upon to date. We believe that wide-area multicast communication is at a substantially increased risk from specific security threats, compared with the same threats in unicast. This arises both from the lack of any form of effective group access control, and from the fact that multicast traffic traverses potentially many more communication links than does a single unicast communication, thereby creating more opportunity for a link attack. We discuss specific threats that are relevant to multicast, and explain why they are so. We propose security mechanisms specifically for multicast groups requiring safeguards that afford protection against some of these threats. More precisely, we propose a version of the IGMP protocol that can reliably enforce subnet-level group access control. We also describe a scalable mechanism to control multicast traffic in transit that can, for example, prevent a misbehaving source from causing undue congestion over the wide-area. >

The conference control channel protocol (CCCP): a scalable base for building conference control applications

Abstract: This paper presents the Conference Control Channel Protocol (CCCP), a new scheme intended for controlling conferences ranging from small, tightly coupled meetings, to extremely large loosely coupled seminars. We describe the requirements of such a scheme, and present a framework for building systems that connect together new and existing applications.

Implementing real time packet forwarding policies using streams

Abstract: This paper describes an implementation of the class based queueing (CBQ) mechanisms proposed by Sally Floyd and Van Jacobson to provide real time policies for packet forwarding. CBQ allows the traffic flows sharing a data link to be guaranteed a share of the bandwidth when the link is congested, yet allows flexible sharing of the unused bandwidth when the link is unloaded. In addition, CBQ provides mechanisms which give flows requiring low delay priority over other flows. In this way, links can be shared by multiple flows yet still meet the policy and Quality of Service (QoS) requirements of the flows. We present a brief description of the implementation and some preliminary preformance measurements. The problems of packet classification are addressed in a flexible and extensible, yet efficient manner, and whilst the Streams implementation cannot cope with very high speed interfaces, it can cope with the serial link speeds that are likely to be loaded.

A rough comparison of the IETF and ATM service models

Abstract: There is much in common between the models of traffic management being devised by the IETF and ATM Forum working groups. The authors' goal is to demonstrate that because of this convergence, there are a number of ways that each can take advantage of the other. The authors discuss service models, link sharing, network provision models, traffic service class hierarchies, borrowing and replacement strategies, delays and throughput, ordering and routing with particular application to the Internet. >

Open Distributed Systems

Abstract: From the Publisher: Gain a detailed understanding of the present and future states of distributed systems, using the recently ratified Open Distributed Processing models as a basis. This new book's comprehensive coverage of distributed systems from the ODP perspective gives you a fresh grasp of the applications enabled by distributed systems and demonstrates how: ? A multimedia conferencing system can be built as a distributed application ? Management can be modeled as a distributed application ? A distributed file system can be built as an example of a user application Each chapter of Open Distributed Systems covers a different aspect of the technology, allowing you to read most chapters independently and quickly home in on the information you need. Featuring approximately 60 illustrations, 30 equations and 100 references, this book is a comprehensive text for students, and a practical guide for engineers.

The World Wide Web: Beneath The Surf

Abstract: The World Wide Web (WWW) is a global information system which is set to revolutionize the world of information search, retrieval and browsing via the Internet. This book serves as an authoritative introduction to concepts and design required to use the WWW. The book is intended for systems operators and managers, IT managers, computer science undergraduates, and general Internet users.

A Rough Comparison of the IETF and ATM Service Models There is much in common between the models of traffic management being devised by the IETF and ATM Forum working groups. The authors’ goal is to demonstrate that because of this convergence, there are a number of ways that each can take advantage of the other.

Abstract: There is much in common between the models of traffic management being devised by the IETF and ATM Forum working groups. The authors' goal is to demonstrate that because of this convergence, there are a number of ways that each can take advantage of the other. The authors discuss service models, link sharing, network provision models, traffic service class hierarchies, borrowing and replacement strategies, delays and throughput, ordering and routing with particular application to the Internet. >

The World Wide Web

Abstract: The World Wide Web WWW is a global information system which is set to revolutionize the world of information search, retrieval and browsing via the Internet

RSVP and Q.2931

Abstract: The paper discusses some of the problems seen with the integration of signaling for support of integrated services Internet over broadband ISDN. In it we contrast the mechanisms employed by the Internet resource reservation protocol, RSVP with those of B-ISDN and Q.2931. We do not propose any solution, but try to give an indication of the direction that signaling for broadband networks must evolve to support more effectively the higher level services that most users will be employing. (4 pages)

Teleservice requirements for management

Abstract: Future advances in conferencing will make it feasible to build servers which collaborate to provide services similar to those of an airline booking system over the networks. Such servers should be able to support real-time queries and modifications to the information stored. We present the management requirements for the services that are providd by these servers.