David L. Tennenhouse

A survey of active network research

Active networks are a novel approach to network architecture in which the switches (or routers) of the network perform customized computations on the messages flowing through them. This approach is motivated by both lead user applications, which perform user-driven computation at nodes within the network today, and the emergence of mobile code technologies that make dynamic network service innovation attainable. The authors discuss two approaches to the realization of active networks and provide a snapshot of the current research issues and activities. They illustrate how the routers of an IP network could be augmented to perform such customized processing on the datagrams flowing through them. These active routers could also interoperate with legacy routers, which transparently forward datagrams in the traditional manner.

Architectural considerations for a new generation of protocols

The current generation of protocol architectures, such as TCP/IP or the ISO suite, seem successful at meeting the demands of todays networks. However, a number of new requirements have been proposed for the networks of tomorrow, and some innovation in protocol structuring may be necessary. In this paper, we review some key requirements for tomorrows networks, and propose some architectural principles to structure a new generation of protocols. In particular, this paper identifies two new design principles, Application Level Framing and Integrated Layer Processing. Additionally, it identifies the presentation layer as a key aspect of overall protocol performance.

ANTS: a toolkit for building and dynamically deploying network protocols

The authors present a novel approach to building and deploying network protocols. The approach is based on mobile code, demand loading, and caching techniques. The architecture of the system allows new protocols to be dynamically deployed at both routers and end systems, without the need for coordination and without unwanted interaction between co-existing protocols. They describe the architecture and its realization in a prototype implementation. To demonstrate how to exploit the architecture, they present two simple protocols that operate within the prototype to introduce multicast and mobility services into a network that initially lacks them.

The AURORA gigabit testbed

Abstract AURORA is one of five U.S. networking testbeds charged with exploring applications of, and technologies necessary for, networks operating at gigabit per second or higher bandwidths. The emphasis of the AURORA testbed, distinct from the other four testbeds, BLANCA, CASA, NECTAR and VISTANET, is research into the supporting technologies for gigabit networking. Like the other testbeds, AURORA itself is an experiment in collaboration, where government initiative (in the form of the Corporation for National Research Initiatives, which is funded by DARPA and the National Science Foundation) has spurred interaction among pre-existing centers of excellence in industry, academia, and government. AURORA has been charged with research into networking technologies that will underpin future high-speed networks. This paper provides an overview of the goals and methodologies employed in AURORA, and points to some preliminary results from our first year of research, ranging from analytic results to experimental prototype hardware. This paper enunciates our targets, which include new software architectures, network abstractions, and hardware technologies, as well as applications for our work.

The VuSystem: a programming system for compute-intensive multimedia

In compute-intensive multimedia applications, the computer not only manipulates media, but also digests it and performs independent actions based on media content. We present a design approach that applies the programming techniques of visualization systems to the development of compute-intensive multimedia applications. We describe an implementation based on this approach, and report performance measurements that demonstrate it is practical. We conclude with a description of some applications that have been implemented and a discussion of the implications for the design and engineering of operating systems.

Toward an active network architecture

Active networks allows users to inject customized programs into the nodes of the network. In this paper, we describe our vision of an active network architecture, outline our approach to its design, and survey the technologies that can be brought to bear on its implementation. In the course of this presentation we identify a number of research questions to be addressed and propose that the research community mount a joint effort to develop and deploy a wide area ActiveNet.

ANTS: network services without the red tape

How well distributed computing systems perform depends a great deal on the network services used to move information among their machines. Yet despite this close correspondence, network services have evolved much more slowly than any other part of the distributed system environment. It is not that the networking community lacks innovative ideas: Internet Protocol version 6, Mobile IP, IP Multicast, and Integrated/Differentiated Services aim to support multimedia applications more effectively and to accommodate more hosts, many of them mobile. Unfortunately, progress in implementing these solutions lags far behind the identified need. The main problem is the way network protocols must change. First, network protocols are the main vehicle for achieving interoperability, so any candidate internetworking protocol has to become a standard. This means possibly years between the time someone identifies a need and the time everyone agrees on how to address it. Once the new protocol has been accepted, more delays occur because it has to be deployed manually and in a way that is compatible with the existing protocols. The paper discusses ANTS, a new approach to deploying network services, which bases interoperability on a programmable network model, not on individual networking protocols. The promise is automatic protocol upgrades, which can hasten progress toward a more responsive Internet.

Toward the software realization of a GSM base station

Advances in processor and analog-to-digital conversion technology have made the software approach an increasingly attractive alternative for implementing radio-based systems. For mobile telephony base stations, the advantages with the new architecture are obvious: great cost savings by using one transceiver per base transceiver station (BTS) instead of one per channel, tremendous flexibility by moving system-specific parameters to the digital part, and allowing the support of a wide range of modulation and coding schemes. This paper considers the software implementation of a GSM BTS, and analyzes the performance of each of its radio interface modules. The performance of each software module is evaluated using both a % CPU metric and a processor-independent metric based on SPEC benchmarks. The results can be used to dimension systems, e,g., to estimate the number of software-based GSM channels that can be supported by a given processor configuration, and to predict the impact of future processor enhancements on BTS capacity. Two novel aspects of this work are the portability of the software modules and the platform-independent evaluation of their computational requirements

The VuNet desk area network: architecture, implementation, and experience

The VuNet is a gigabit-per-second desk-area ATM network that interconnects general-purpose workstations, network-based multimedia devices, and bridges to other networks, workstations access the multimedia devices over the network and coordinate the movement of information streams among the different parts of the system. This architecture presents several advantages over the traditional workstation-centric models, including the ability to easily share network-based devices, to access nonlocal devices, and to relieve the workstation of a portion of the I/O work. This paper describes the philosophy, implementation choices, advantages, and limitations of the VuNet ATM network implementation, as well as performance and current status. >

The SpectrumWare approach to wireless signal processing

The SpectrumWare project is applying a software oriented approach to wireless communication and distributed signal processing. Advances in processor and analog-to-digital conversion technology have made it possible to implementvirtual radios that directly sample wide bands of the RF spectrum and process these samples in application software. The elimination of dedicated hardware introduces tremendous flexibility into a wireless communication system. Our approach goes further than the software implementation of traditional signal processing functions. We use processor and network memory to temporally decouple the sample streams from the software modules so that the bulk of the processing can be realized within virtual time programming environments. Decoupling relaxes the temporal constraints on the processing algorithms and their execution. This paper describes the SpectrumWare concept, our experimental approach, and the implications that this approach has for wireless signal processing algorithms.