Journal: TIK Report

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ETH Zurich, Computer Engineering and Networks Laboratory

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Publications 1 - 10 of 203
  • The VersaKey Framework: Versatile Group Key Management
    Item type: Report
    Waldvogel, Marcel; Caronni, Germano; Sun, Dan; et al. (1998)
    TIK Report
    Middleware supporting secure applications in a distributed environment faces several challenges. Scalable security in the context of multicasting or broadcasting is especially hard when privacy and authenticity is to be assured to highly dynamic groups where the application allows participants to join and leave at any time. Unicast security is well-known and has widely advanced into production state. But proposals for multicast security solutions that have been published so far are complex, often require trust in network components or are inefficient. In this paper, we propose a framework of new approaches for achieving scalable security in IP multicasting. Our solutions assure that that newly joining members are not able to understand past group traffic, and that leaving members may not follow future communications. For versatility, our framework supports a range of closely related schemes for key management, ranging from tightly centralized to fully distributed and even allows switching between these schemes on-the-fly with low overhead. Operations have low complexity (O(log N) for joins or leaves) grants scalability even for very large groups. We also present a novel concurrency-enabling scheme, which was devised for completely distributed key management. In this paper we discuss the requirements for secure multicasting, present our flexible system, and evaluate its properties, based on the existing prototype implementation.
  • The Cumulus Pricing Scheme and its integration into a generic and modular Internet Charging System for differentiated services
    Item type: Report
    Stiller, Burkhard; Gerke, Jan; Reichl, Peter; et al. (2000)
    TIK Report
    Pricing and charging are the most important management functionalities future commercial networks need to offer. Since the Internet is on the move to provide differentiated services, for the backbone based on the Differentiated Services Architecture (DiffServ), suitable and scalable management mechanisms are required. Based on a new view of pricing, considered as important management information, on one hand, the Cumulus Pricing Scheme (CPS) proposed targets particularly at DiffServ technology and it is the only approach known so far defining a clear relation between different time-scales of accounting periods, measurement periods, and charging periods. Prices in this scheme are based on flat fees and hence predictable and transparent. On the other hand the scheme is flexible enough to allow network management according to the actual forces of the market. CPS is backed by the design of a generic and modular Internet Charging System. It offers a service-independent architecture and integrates economically-controlled network management functions of charge calculation and pricing. It has been instantiated to an Internet Charge Calculation and Accounting System (ICCAS) to offer user support functions and is utilized for different Internet services. In particular, it has been applied explicitly in this work to DiffServ and the new Cumulus Pricing Scheme.
  • Searching for Periodic Flows in an Internet Backbone
    Item type: Report
    Flury, Placi (2005)
    TIK Report
    If questioned on a traffic pattern occurring every day at precisely the same time, one would intuitively attribute it to some timed application such as e.g. amirror update. Nonetheless has research so far neglected to investigate the key properties of above, apparently obvious, phenomenon. This report presents a methodology for detecting traffic exchanges at periodical intervals between hosts. We applied the methodology on NetFlow statistics of an Internet backbone. We discovered about 15% of the TCP traffic on a border router to be periodic; moreover, comparably few flows contribute to this phenomenon. With the prospect of traffic engineering we examined the traffic s property of time persistence.
  • The design and implementation of a flexible middleware for multimedia communications comprising usage experience
    Item type: Report
    Stiller, Burkhard; Class, Christina; Waldvogel, Marcel; et al. (1998)
    TIK Report
    Distributed multimedia applications require a variety of communication services. These services and different application demands have to be provided and supported within end-systems in an efficient and integrated manner, combining the precise specification of Quality-of-Service (QoS) requirements, application interfaces, multicast support, and security features. The Da CaPo++ system presented in this paper provides an efficient middleware and application framework for multimedia applications, capa ble of handling various types of applications in a modular fashion. Applications’ needs and communication demands are specified by values in terms of QoS attributes and functional properties, such as multicast groups, encryption or authentication requirements. Da CaPo++ automatically generates suitable communication protocols, provides for an efficient run-time support and offers an easy-to-use, object-oriented application programming interface. Its applicability for real-life scenarios was shown by various prototype implementations. Extensive performance evaluations have been carried out and practical experiences have yielded numerical results and conclusions.
  • Virtualizing active networks for Telecom environments
    Item type: Report
    Brunner, Marcus; Stadler, Rolf (1999)
    TIK Report
    The paper addresses the question on how the benefits of active networking, such as customized packet processing inside the network and flexible service management, can be realized in a telecom environment. More precisely, we ask: How can a network provider, whose infrastructure is based on active networking technology, support a large number of customers, all of which independently install and run their own customized active services in the providers domain? Our approach is based on network virtualization, and the goal of this paper is to demonstrate that virtualization of active networks can be achieved with considerable benefits for customers and providers and with limited costs. Our work uses the concept of the Virtual Active Network (VAN), a generic service that is offered by an active network provider to customers. We have realized the VAN concept and implemented a VAN provisioning and management architecture on ANET, an active networking platform we have developed. ANET is an all-software, functional prototype of an active network, which allows for experimentation with great flexibility. Further, we have worked out a design for a VAN-enabled node operating system for a high-performance active network node which is currently being built by our laboratory at ETH Zurich in collaboration with a group at Washington University in St. Louis.
  • Symbolic Reachability Graph Generation for High-level Models based on Synthesized Operators
    Item type: Report
    Lampka, Kai (2009)
    TIK Report
    This paper introduces a new technique for generating Binary Decision Diagrams (BDDs) representing high-level model’s underlying state/tran- sition systems. The obtained decision diagram may serve as input for various analysis methods such as symbolic (probabilistic) model checking and/or Markovian performance and reliability analysis. As usual the pro- posed technique makes use of partitioned symbolic reachability analysis. However, contrary to existing techniques it neither relies on pregenerated symbolic representations of transition relations, nor does it make use ofstandard BDD-manipulating algorithms. Instead, symbolic reachability analysis is carried out by means of customized BDD-algorithms directly synthesized from high-level models to be analyzed. Overall the presentedapproach yields the core of a new tool bench for the symbolic analysis of state-based system descriptions. The tool bench is implemented on topof the Eclipse Modeling Framework and exploits Java Emitter Templates for code synthesis. Standard benchmark models show that for generating high-level models underlying state/transition systems significant improve- ments with respect to CPU time and memory consumption can be real- ized, ultimately allowing the verification of larger and much more complex systems.
  • Optimized software synthesis for digital signal processing algorithms - an evolutionary approach
    Item type: Report
    Teich, Jürgen; Zitzler, Eckart; Bhattacharyya, Shuvra S. (1998)
    TIK Report
    This paper addresses the problem of trading-off between the minimization of program and data memory requirements of single-processor implementations of dataflow programs. Based on the formal model of synchronous data flow (SDF) graphs [LM87], so called single appearance schedules are known to be program-memory optimal. Among these schedules, buffer memory schedules are investigated and explored based on a two-step approach: (1) An Evolutionary Algorithm (EA) is applied to efficiently explore the (in general) exponential search space of act or firing orders. (2) For each order, the buffer costs are evaluated by applying a dynamic programming post- optimization step (GDPPO). This iterative approach is compared to existing heuristics for buffer memory optimization.
  • Partially-shared Zero-Suppressed Multi-Terminal BDDs: Concept, Algorithms and Applications
    Item type: Report
    Lampka, Kai; Siegle, Markus; Ossowski, Jörn; et al. (2008)
    TIK Report
    Multi-Terminal Binary Decision Diagrams (MTBDDs) are a well accepted technique for the state graph (SG) based quantitative analysis of large and complex systems specified by means of high-level model description techniques. However, this type of Decision Diagram (DD) is not always the best choice, since finite functions with small satisfaction sets, and where the fulfilling assignments possess many 0-assigned positions, may yield relatively large MTBDD based representations. Therefore, this article introduces zero-suppressed MTBDDs and proves that they are canonical representations of multi-valued functions on finite (input) sets. For manipulating DDs of this new type, possibly defined over different sets of function variables, the concept of partially-shared zero-suppressed MTBDDs and respective algorithms are developed. The efficiency of this new approach is demonstrated by comparing it to the well-known standard type of MTBDDs, where both types of DDs have been implemented by us within the C++-based DD-package Jinc. The benchmarking takes place in the context of Markovian analysis and probabilistic model checking of systems. In total, the presented work extends existing approaches, since it not only allows one to directly employ (multi-terminal) zero-suppressed DDs in the field of quantitative verification, but also clearly demonstrates their efficiency.
  • SCSM - synchronous composition of sequential machines
    Item type: Report
    Fierz, Hugo (1994)
    TIK Report
    The SCSM formalism allows to define event driven synchronous systems by means of expressions formed by sum, product and restriction operators applied to non-deterministic sequential machines. Deterministic expressions are obtained through global product restrictions, which correlate transitions of non-deterministic components with states of other components. SCSM is usefull as denotation domain for synchronous system description languages, especially for models concerning reactive systems.
  • Comparison of Biclustering Methods: A Systematic Comparison and Evaluation of Biclustering Methods for Gene Expression Data
    Item type: Report
    Prelić, Amela; Bleuler, Stefan; Zimmermann, Philip; et al. (2005)
    TIK Report
    In recent years, there have been various efforts to over-come the limitations of standard clustering approaches for the analysis of gene expression data by grouping genes and samples simultaneously.The underlying concept, which is often referred to as biclustering, allows to identify sets of genes sharing compatible expression patterns across subsets of samples, and its usefulness has been demonstrated for different organisms and data sets. Several biclustering methods have been proposed in the literature; however, it is not clear how the different techniques compare to each other with respect to the biological relevance of the clusters as well as to other characteristics such as robustness and sensitivity to noise. Accordingly, no guidelines concerning the choice of the biclustering method are currently available.
Publications 1 - 10 of 203