Over the last decade, programmable Network Processors (NPs) have become widely used in Internet routers and other network components. NPs enable rapid development of complex packet processing functions as well as rapid response to changing requirements. In the network research community, the use of NPs has been limited by the challenges associated with learning to program these devices and with using them for substantial research projects. This paper reports on an extension to the Open Network Laboratory testbed that seeks to reduce these "barriers to entry" by providing a complete and highly configurable NP-based router that users can access remotely and use for network experiments. The base router includes support for IP route lookup and general packet filtering, as well as a flexible queueing sub-system and extensive support for performance monitoring. In addition, it provides a plugin environment that can be used to extend the router's functionality, enabling users to carry out significant network experiments with a relatively modest investment of time and effort. This paper describes our NP router and explains how it can be used. We provide several examples of network experiments that have been implemented using the plugin environment, and provide some baseline performance data to characterize the overall system performance. We also report that these routers have already been used for ten non-trivial projects in an advanced architecture course where most of the students had no prior experience using NPs.

In recent years, overlay networks have become an important vehicle for delivering Internet applications. Overlay network nodes are typically implemented using general purpose servers or clusters. We investigate the performance benefits of more integrated architectures, combining general-purpose servers with high performance Network Processor (NP) subsystems. We focus on PlanetLab as our experimental context and report on the design and evaluation of an experimental PlanetLab platform capable of much higher levels of performance than typical system configurations. To make it easier for users to port applications, the system supports a fast path/slow path application structure that facilitates the mapping of the most performance-critical parts of an application onto an NP subsystem, while allowing the more complex control and exception-handling to be implemented within the programmer-friendly environment provided by conventional servers. We report on implementations of two sample applications, an IPv4 router, and a forwarding application for the Internet Indirection Infrastructure. We demonstrate an 80x improvement in packet processing rates and comparable reductions in latency.

The Open Network Laboratory (ONL) is a remotely accessible network testbed of high performance routers which has been designed with an eye towards ease of use for users from the naïve to the expert. The system is built around a set of high-performance routers that are extendible and easily configurable through the Remote Laboratory Interface (RLI), an intuitive graphical interface. The RLI also makes it easy to configure packet filters in the routers, assign flows or flow aggregates to separate queues with configurable QoS and attach hardware monitoring points to real-time charts. The RLI’s real-time charts and user data facility makes it easy to directly view the effects of traffic as it moves through a router, allowing the user to gain better insight into system behavior and create compelling demonstrations. Each port of the router is equipped with an embedded processor that supports software plugins which allow users to extend the system’s functionality. This paper describes the ONL and how it can be used in networking education. You should checkout our web site onl.arl.wustl.edu which includes a short video.

Video-conferencing is an efficient tool for distributed collaboration. With the wider availability of broadband wide area networks, such as the Internet2, we can expect an increasing demand for video-conferences conducted over broadband wide area networks. We present a conference control protocol for a highly interactive conference paradigm and its collaboration environment. In such a collaboration environment, a fixed number of channels (three) for multimedia traffic, as well as a common control channel, are used. We propose a conference control protocol that uses a three-channel rotation floor control scheme to coordinate access to the shared media channels and avoid race conditions. Experimental results, as well as the implementation in a research video-conferencing system for wide area networks, show that the proposed protocol can effectively eliminate race conditions while maintaining scalability and reliability.

High quality videoconferencing is an efficient tool for interactive scientific collaboration. With the wide deployment of broadband wide area IP networks such as Intemet2, there is an increasing demand for improved remote collaboration using these networks. In order to make the high quality videoconferencing toolkits for local high-speed networks available over wide area IP networks, issues that are usually insignificant on local area networks must be considered. In this paper, we describe a high quality videoconferencing system we developed based on an earlier version of the system for local area networks. To solve the problems associated with real-time video and audio transmission over wide area IP networks, we added a specifically design hardware device called an adaptation layer translator (ALX). A conference control protocol based on a channel rotation scheme is also developed to coordinate the participants in an ALX-based conference.

Abstract To be an effective platform for performance‐sensitive real‐time systems, commodity‐off‐the‐shelf (COTS) distributed object computing (DOC) middleware must support application quality of service (QoS) requirements end‐to‐end. However, conventional COTS DOC middleware does not provide this support, which makes it unsuited for applications with stringent latency, determinism, and priority preservation requirements. It is essential, therefore, to develop standards‐based, COTS DOC middleware that permits the specification, allocation, and enforcement of application QoS requirements end‐to‐end. The real‐time CORBA and messaging specifications in the CORBA 2.4 standard are important steps towards defining standards‐based, COTS DOC middleware that can deliver end‐to‐end QoS support at multiple levels in distributed and embedded real‐time systems. These specifications still lack sufficient detail, however, to portably configure and control processor, communication, and memory resources for applications with stringent QoS requirements. This paper provides four contributions to research on real‐time DOC middleware. First, we illustrate how the CORBA 2.4 real‐time and messaging specifications provide a starting point to address the needs of an important class of applications with stringent real‐time requirements. Second, we illustrate how the CORBA 2.4 specifications are not sufficient to solve all the issues within this application domain. Third, we describe how we have implemented portions of these specifications, as well as several enhancements, using TAO, which is our open‐source real‐time CORBA ORB. Finally, we evaluate the performance of TAO empirically to illustrate how its features address the QoS requirements for certain classes of real‐time applications. Copyright © 2001 John Wiley & Sons, Ltd.