The Internet is being used to carry voice conversations. Sometimes the quality is acceptable, and at other times the voice is unintelligible. In this paper, we describe the results of a set of measurements on intrastate, cross country, and international Internet connections. The measurements are used to determine the relationships between the delay that is inserted to compensate for the variation in network delay, the strategy that is used to restore lost packets, and the "quality" of the voice connection. The "quality" of a connection is defined as the fraction of the time that a channel is free of distortion for intervals that are long enough to transmit active speech segments. We also examine the sensitivity of our quality measure to modifying the required length of the distortion free intervals. We have found that, with the proper combination of packet restoration, receiver delay and patience on the part of users, connections can be established that provide reasonably good voice co...

We outline challenges faced in the management and control of broadband networks, describe some typical network management scenarios in this environment, and outline the technical advances required for its realization. We describe the work of the COMET group at Columbia University that deals with these challenges and describe the characteristics of the type of system necessary to enable effective management of these networks. The main feature of the system allows the manager to interact with the network through primitives of a much higher semantic level than those provided by existing management services. 1 Introduction Research, development and implementation of network management systems has progressed to the point where we are now seeing the availability of standards-based management software from commercial vendors, and the deployment of these products in operational networks. Similarly, hardware vendors for network components such as switches, bridges, and routers, are incorporat...

Just as broadband networks will enable user-to-user communications to extend from textual services to those employing multimedia, they will also make possible a management environment that can take advantage of increased bandwidth and multimedia technology. The fundamental advances incorporated in such an environment can provide efficient solutions to the problem of information management. To establish this environment, we tackle the fundamental problems of observability and controllability of broadband networks. A virtual world provides a next-generation network management interface through which a user can observe and interact with the network directly in real time. The system we are developing uses a 3D virtual world as the user interface for managing a large gigabit ATM network. It provides the capability for experimentation in all aspects of network transport, control, and management.

High-performance event filtering is an essential service in a distributed systems environment. We are developing an event filtering architecture to efficiently process the large volume of event traffic generated by distributed dynamic multi-point (DDMP) applications (such as automated monitoring and fault management in distributed systems). Our architecture supports the dynamic (re)configuration and optimization of event filters in large-scale distributed systems. Our work

High-performance event filtering is an essential service in a distributed processing environment. We are developing an object-oriented event filtering framework to efficiently process the large volume of event traffic generated by dynamic multi-point (DMP) applications (such as automated fault management in telecommunication systems). Our framework, which is based on CORBA, supports the automated generation and optimization of event filters in a distributed system. Our work

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