Multicast Routing of Hierarchical Data

The issue of multicast of broadband, real-time data in a heterogeneous environment, in which the data recipients differ in their reception abilities, is considered. Traditional multicast schemes, which are designed to deliver all the source data to all recipients, offer limited performance in such an environment, since they must either force the source to overcompress its signal or restrict the destination population to those who can receive the full signal. We present an approach for resolving this issue by combining hierarchical source coding techniques, which allow recipients to trade off reception bandwidth for signal quality, and sophisticated routing algorithms that deliver to each destination the maximum possible signal quality. The field of hierarchical coding is briefly surveyed and new multicast routing algorithms are presented. The algorithms are compared in terms of network utilization efficiency, lengths of paths, and the required mechanisms for forwarding packets on the resulting paths

Regular Topologies for Gigabit Wide-Area Networks

In general terms, this project aimed at the analysis and design of techniques for very high-speed networking. The formal objectives of the project were to: (1) Identify switch and network technologies for wide-area networks that interconnect a large number of users and can provide individual data paths at gigabit/s rates; (2) Quantitatively evaluate and compare existing and proposed architectures and protocols, identify their strength and growth potentials, and ascertain the compatibility of competing technologies; and (3) Propose new approaches to existing architectures and protocols, and identify opportunities for research to overcome deficiencies and enhance performance. The project was organized into two parts: 1. The design, analysis, and specification of techniques and protocols for very-high-speed network environments. In this part, SRI has focused on several key high-speed networking areas, including Forward Error Control (FEC) for high-speed networks in which data distortion is the result of packet loss, and the distribution of broadband, real-time traffic in multiple user sessions. 2. Congestion Avoidance Testbed Experiment (CATE). This part of the project was done within the framework of the DARTnet experimental T1 national network. The aim of the work was to advance the state of the art in benchmarking DARTnet's performance and traffic control by developing support tools for network experimentation, by designing benchmarks that allow various algorithms to be meaningfully compared, and by investigating new queueing techniques that better satisfy the needs of best-effort and reserved-resource traffic. This document is the final technical report describing the results obtained by SRI under this project. The report consists of three volumes: Volume 1 contains a technical description of the network techniques developed by SRI in the areas of FEC and multicast of real-time traffic. Volume 2 describes the work performed under CATE. Volume 3 contains the source code of all software developed under CATE

Modeling Correlated Alarms in Network Management Systems

We introduce a new model for describing the behavior of complex interconnection networks in the presence of faults. Using our model it is possible to obtain the detailed behavior of a faulty telecommunication network by specifying some parameters that describe its physical characteristics. We describe our model, we show how it can be applied to study some real network management structures, and we give some experimental data to evaluate its relation to existing standard analytical models. 1 Introduction Modern telecommunication networks have grown in complexity beyond the point where they can be managed by a manual process alone. This complexity gave rise to automated network management (NM) systems that interact with network elements (NEs) to gain data about their behavior and performance, and to control their behavior by setting operational parameters. Several protocols have been proposed for the interaction between NEs and NM systems. At present, the Simple Network Management Proto..

Gateway Based Approach for Conducting Multiparty Multimedia Sessions over Heterogeneous Signaling Domains

Emerging networking technologies tend to be introduced complete with protocols for managing their own resources, for example, routing, resource reservation, and signaling. Each network offers a quality of service (QOS) interface, and applications take advantage of network signaling to demand and reserve predictive service. Whereas such interaction enhances the performance of applications that run on a specific network, it creates a challange for applications that run over heterogeneous infrastructure spanning multiple signaling domains. We present an approach for managing multiparty, multimedia sessions in a heterogeneous internetwork spanning multiple signaling domains and diverse link capacities. Participants utilize the native signaling on their respective domains and interact with participants on other domains through signaling gateways that bridge the domains and provide translation of signaling procedures and QOS semantics. Data streams are transmitted using hierarchica..

NETAL: a Simulation Environment for Network Management Systems

this document is to describe the software structure and usage of NETAL. NETAL reproduces what happens in a telecommunication system when a fault (or several faults) occurs by implementing all the models described in [1] in a fully parameterized way. NETAL is not designed to be specifically used for a particular network but allows the user to specify arbitrary network topologies and to control all timing and probability parameters that determine the behavior of the network elements (NEs) and their managers. The general NM model employed in NETAL consists of a three-tiered hierarchy. At the base of the hierarchy are the NEs that constitute the objects of the network management system. All NEs are connected to regional NE-Operating System (OS) managers. NE-OSs are at the second level of the hierarchy and keep NM information of their children in a local storage area (NE-OS-MIB). NM-managers (NM-Ms) are at the top of the hierarchy and are responsible for summarizing the information of a fairly large system of NE-OS managers. Each NE can be connected to only one NE-OS, and each NE-OS can be connected to only one NM-M. Multiple NM-Ms can manage different NM systems, and they can communicate among them. a more detailed description of this NM model is in [1]. 2 Structur

Elements of Trusted Multicasting

Multicast is rapidly becoming an important mode of communication as well as a good platform for building group-oriented services. However, to be used for trusted communication, current multicast schemes must be supplemented by mechanisms for protecting traffic, controlling participation, and restricting access of unauthorized users to the data exchanged by the participants. In this paper, we consider fundamental security issues in building a trusted multicast facility. We discuss techniques for group-based data encryption, authentication of participants, and preventing unauthorized transmissions and receptions. 1 Introduction Emerging distributed applications, such as multimedia teleconferencing, computer-supported collaborative work, and remote consultation and diagnosis systems for medical applications, depend on efficient information exchange among multiple participants. Network-based multi-destination switching is an essential mode of communication for such applications. Little co..

HMC: A system for Heterogeneous Multicast over ATM

A multimedia session normally consists of participants which differ widely in their preferences and available resources (like access bandwidth and processing capacity) . Heterogeneous MultiCast (HMC) is a communication paradigm which caters to such varying resource constraints of the participants. The approach is based on sources encoding streams in layers which can be individually ordered. Each participant specifies individualized fidelity level for each stream he/she wants to receive. One of the key issues is the generation and reception of multiple, related substreams. The mechanisms described allow effective partitioning of streams into layers, signal multiplexing and demultiplexing, packetization and de-packetization of layered data and play-out synchronization of data units. ATM infrastructure is used for connection-based transport and cell switching. We describe how ATM signaling can be used to implement the HMC communication paradigm