Present day routers typically employ monolithic operating systems which are not easily upgradahle and extensible. With the rapid rate of protocol development it is becoming increasingly important to dynamically upgrade router software in an incre-mental fashion. We have designed and implemented a high performance, modular, extended integrated services router software architecture in the NetBSD operating system kernel. This architecture allows code modules, called plugins, to be dynamically added and configured at run time. One of the novel features of our design is the ability to bind different plugins to individual flows; this allows for distinct plugin implementations to seamlessly coexist in the same runtime environment. High performance is achieved through a carefully designed modular architecture; an innovative packet classification algorithm that is both powerful and highly efficient; and by caching that exploits the flow-like character-istics of Internet traffic. Compared to a monolithic best-effort kernel, our implementation requires an average increase in packet processing overhead of only 8 % , or 500 cycles/2.lms per packet when run-ning on a P61233. 1.1 Keywords High performance integrated services routing, modular router architecture, router plugins 2.

In contemporary operating systems, continuous media (CM) applications are sensitive to the behaviour of other tasks in the system. This is due to contention in the kernel (or in servers) between these applications. To properly support CM tasks, we require “Quality of Service Firewalling” between different applications. This paper presents a memory management system supporting Quality of Service (QoS) within the Nemesis operating system. It combines application-level paging techniques with isolation, exposure and responsibility in a manner we call self-paging. This enables rich virtual memory usage alongside (or even within) continuous media applications. 1

Video distribution over the Internet poses many challenges. Due to the best-effort nature of today's public data networks, end system applications cannot rely on either bandwidth or delay guarantees. We designed and implemented a prototype of a multicast video distribution architecture involving knowledgeable active routers, a scalable video codec based on wavelet transformation, and a high-performance video scaling algorithm implemented as a router plugin. The plugin scales the video with an average overhead of only 22 tts per video datagram and is installed on-the-fly on the routers after the sender starts transmitting video for the first time. Through experiments on our test network, we show that we can dramatically improve the video quality on the receivers (up to 15 dB PSNR) by scaling the video on the routers to almost any target bandwidth. The target bandwidth is evaluated by the router solely based on monitoring of the load situation of the router's downstream links and can be adjusted within 50 ms.

Distributed multimedia applications require a variety of communication services. These services and different application requirements have to be provided and supported within (1) end-systems in an efficient and integrated manner, combining the precise specification of Quality-ofService (QoS) requirements, application interfaces, multicast support, and security features, and within (2) the network. The Da CaPo++ system presented here provides an efficient end-system middleware for multimedia applications, capable of handling various types of applications in a modular fashion. Application needs and communication demands are specified by values in terms of QoS attributes and functional properties, such as encryption requirements or multicast support. Da CaPo++ automatically configures suitable communication protocols, provides for an efficient run-time support, and offers an easy-to-use, object-oriented application programming interface. While its applicability to real-life applications was shown by prototype implementations, performance evaluations have been carried out yielding practical experiences and numerical results.

Present day routers typically employ monolithic operating systems which are not easily upgradable and extensible. With the rapid rate of protocol development it is becoming increasingly important to dynamically upgrade router software in an incremental fashion. We have designed and implemented a high performance, modular, extended integrated services router software architecture in the NetBSD operating system kernel. This architecture allows code modules, called plugins, to be dynamically added and configured at run time. One of the novel features of our design is the ability to bind different plugins to individual flows; this allows for distinct plugin implementations to seamlessly coexist in the same runtime environment. High performance is achieved through a carefully designed modular architecture; an innovative packet classification algorithm that is both powerful and highly efficient; and by caching that exploits the flow-like characteristics of Internet traffic. Compared to a mon...

As the World Wide Web experiences increasing commercial and mission-critical use, server systems are expected to deliver high and predictable performance. The phenomenal improvement in microprocessor speeds, coupled with the deployment of clusters of commodity workstations has enabled server systems to meet the continually increasing performance demands in a cost-effective and scalable manner. However, as the volume, variety and sophistication of services oered by server systems increase, eective support for providing dierentiated and predictable quality of service has also become important. For example, it is often desirable to dierentiate between the resources allocated to virtual web sites hosted on a server system so as to provide predictable performance to individual sites, regardless of the load imposed upon others. Server systems lack adequate support for providing predictable performance to hosted services in terms of metrics that are meaningful to server applications, such...

Abstract. AMnet 2.0 is an improved architecture for programmable networks that is based on the experiences from the previous implementation of AMnet. This paper gives an overview of the AMnet architecture and Linux-based implementation of this software router. It also discusses the differences to the previous version of AMnet. AMnet 2.0 complements application services with net-centric services in an integrated system that provides the fundamental building blocks both for an active node itself and the operation of a larger set of nodes, including code deployment decisions, service relocation, resource management. 1

In this paper, we describe the vision and the design of a programming environment, called Shangri-La, aimed at making future generations of packet-processing systems – multi-core, light-weight threaded hardware in general, and network processor (NP)-based systems in particular – as easily programmable as today’s workstations and servers. Our environment consists of: (1) a domainspecific programming language for specifying packetprocessing applications, (2) a compiler that incorporates profile-guided techniques for mapping packet-processing applications onto complex packet-processing system architectures, and (3) a run-time system that dynamically adapts resource allocations to create systems that are robust against attacks and that optimize performance and power consumption for the current network conditions. We justify our design and articulate the challenges in designing each of these components. 1.

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I believe that the process of earning a PhD degree fundamentally changes the way one thinks. And one’s advisor is the most significant contributor to such a change. Harrick Vin has striven hard to make me think differently, to convert me into a scientist from an engineer. Harrick’s insistence on elegance of presentation both in writing and in talking has been quite valuable in honing my skills. His rigorous understanding, cute insights and passionate criticism have made my dissertation better by the day, and my PhD a pleasant experience overall. I have cherished many incredibly lengthy and interesting, but never tiring, meetings with him on both technical and philosophical issues. His personal warmth and support during happy and tough times, and his patience and nicety during heated discussions and everyday interactions have given me the necessary protection and confidence to keep going. Thanks for everything Harrick. Over the past five years, I have also been fortunate to work closely with Lorenzo Alvisi and Mike Dahlin. Both have been great mentors in their own right. I am thankful to Lorenzo for believing in me more than I did in myself at one point