Institut für Informatik und Computational Science
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Seminarband: Sensornetze
(2004)
In this paper we report about the recently completed porting of GAMMA to the Netgear GA621 Gigabit Ethernet adapter, and provide a comparison among GAMMA, MPI/GAMMA, TCP/IP, and MPICH/TCP, based on the Netgear GA621 and the older Netgear GA620 network adapters and using different device drivers, in a Gigabit Ethernet cluster of PCs running Linux 2.4. GAMMA (the Genoa Active Message MAchine) is a lightweight messaging system based on an Active Message-like paradigm, originally designed for efficient exploitation of Fast Ethernet interconnects. The comparison includes simple latency/hspace{0pt}bandwidth evaluation of the messaging systems on both adapters, as well as performance comparisons based on the NAS NPB and an end-user fluid dynamics application called Modular Ocean Model (MOM). The analysis of results provides useful hints concerning the efficient use of Gigabit Ethernet with clusters of PCs. In particular, it emerges that GAMMA on the GA621 adapter, with a combination of low end-to-end latency (8.5 $mu$s) and high throughput (118.4 MByte/s), provides a performing, cost-effective alternative to proprietary high-speed networks, e.g.~Myrinet, for a wide range of cluster computing applications.
In order to take full advantage of Grid environments, applications need to be able to run on various heterogeneous platforms. Distributed runs across several clusters or supercomputers for example, require matching binaries at each site. Thus, at some stage, each Grid enabled application needs to be recompiled for every platform. Up to now, creating matching binaries on different platforms was a manual, sequential, slow, and very error-prone process. Developers had to log into each machine, transfer source code, check consistency and recompile if necessary. This cumbersome procedure is surely one reason for the (still existing) lack of production Grid computing. Gridmake, a tool to automate and speed up this procedure is presented in this paper.
Characterizing Grids
(2003)
We present a new data model approach to describe the various objects that either represent the Grid infrastructure or make use of it. The data model is based on the experiences and experiments conducted in heterogeneous Grid environments. While very sophisticated data models exist to describe and characterize e.g. compute capacities or web services, we will show that a general description, which combines {em all} of these aspects, is needed to give an adequate representation of objects on a Grid. The Grid Object Description Language (GODsL)} is a generic and extensible approach to unify the various aspects that an object on a Grid can have. GODsL provides the content for the XML based communication in Grid migration scenarios, carried out in the GridLab project. We describe the data model architecture on a general level and focus on the Grid application scenarios.
PCG-Agreement Dokument
(2004)
This paper analyses data privacy issues as they arise from different deployment scenarios for networks that use embedded sensor devices. Maintaining data privacy in pervasive environments requires the management and implementation of privacy protection measures close to the data source. We propose a set of atomic privacy parameters that is generic enough to form specific privacy classes and might be applied directly at the embedded sensor device.
With the next generation Internet protocol IPv6 at the horizon, it is time to think about how applications can migrate to IPv6. Web traffic is currently one of the most important applications in the Internet. The increasing popularity of dynamically generated content on the World Wide Web, has created the need for fast web servers. Server clustering together with server load balancing has emerged as a promising technique to build scalable web servers. The paper gives a short overview over the new features of IPv6 and different server load balancing technologies. Further, we present and evaluate Loaded, an user-space server load balancer for IPv4 and IPv6 based on Linux.
Design Issues in the Implementation of MPI2 One Sided Communication in Ethernet based Networks
(2007)
In current research, one sided communication of the MPI2 standard is pushed as a promising technique [6, 7, 10, 18]. But measurements of applications and MPI2 primitives show a different picture [17]. In this paper we analyze de sign issues of MPI2 one sided communication and its im plementations. We focus on asynchronous communication for parallel applications in Ethernet cluster environments. Further, one sided communication is compared to two sided communication. This paper will prove that the key problem to performance is not only the implementation of MPI2 one sided communication - it is the design.
SPAM ist in den letzten Jahren zur großten Bedrohung der E-Mail-Kommunikation herangewachsen - jedoch nicht nur auf diesen Kommunikationsweg beschrankt. Mit steigender Anzahl von VoIP-Anschlüssen werden auch hier die teilnehmenden Benutzer mit SPAM-Anrufen (SPIT) konfrontiert werden. Neben derzeit diskutierten juristischen Maßnahmen müssen auch technische Abwehrmaßnahmen geschaffen werden, welche SPAM erkennen und vermeiden können. Dieser Beitrag stellt zwei Erweiterungen für das VoIP-Protokoll SIP vor, welche es erstens den Providern ermöglichen, SPIT-Einschätzungen über den Anrufer zum angerufenen Benutzer zu übermitteln und zweitens den Angerufenen die Möglichkeit geben, mit einer Kostenanforderung auf potentielle SPIT-Anrufe zu reagieren.