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Networking, IEEE/ACM Transactions on

Issue 4 • Date Aug 2000

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Displaying Results 1 - 10 of 10
  • Worst-case traffic in a tree network of ATM multiplexers

    Page(s): 507 - 516
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (296 KB)  

    We study tree networks of discrete-time queues loaded with periodic traffic sources. By using the so-called Benes method, exact closed-form expressions are obtained for the queue length distributions. The models developed can be used to study the superposition of periodic sources emitting bursts of cells in ATM networks. The results obtained show the significant effect that this kind of traffic can have on the performance of these systems View full abstract»

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  • Performance of split routing algorithm for three-stage multicast networks

    Page(s): 526 - 534
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (284 KB)  

    This paper studies three-stage Clos (1953) switching networks for multicast communications in terms of their blocking probabilities on a random traffic model. Even though the lack of multicast capability in input-stage switches requires a prohibitively large number of middle switches to provide compatible requests with nonblocking paths, the probabilistic model gives an observation that the blocking probability decreases drastically and then approaches zero as the number of middle switches is far less than the theoretical bound. The S-shaped curves of blocking probability versus degree of fanout indicate that high fanout requests are mostly blocked at some given reference network utilization. A split routing algorithm and its blocking probability are introduced to enhance the routability of the high fanout requests. We also corroborate the analytic model by performing network simulations based on a random request generator and a random routing strategy View full abstract»

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  • End-to-end delay analysis of videoconferencing over packet-switched networks

    Page(s): 479 - 492
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (268 KB)  

    Videoconferencing is an important global application-it enables people around the globe to interact when distance separates them. In order for the participants in a videoconference call to interact naturally, the end-to-end delay should be below human perception; even though an objective and unique figure cannot be set, 100 ms is widely recognized as the desired one-way delay requirement for interaction. Since the global propagation delay can be about 100 ms, the actual end-to-end delay budget available to the system designer (excluding propagation delay) can be no more than 10 ms. We identify the components of the end-to-end delay in various configurations with the objective of understanding how it can be kept below the desired 10-ms bound. We analyze these components step-by-step through six system configurations obtained by combining three generic network architectures with two video encoding schemes. We study the transmission of raw video and variable bit rate (VBR) MPEG video encoding over (1) circuit switching; (2) synchronous packet switching; and (3) asynchronous packet switching. In addition, we show that constant bit rate (CBR) MPEG encoding delivers unacceptable delay-on the order of the group of pictures (GOP) time interval-when maximizing the quality for static scenes. This study aims at showing that having a global common time reference, together with time-driven priority (TDP) and VBR MPEG video encoding, provides adequate end-to-end delay, which is (1) below 10 ms; (2) independent of the network instant load; and (3) independent of the connection rate. The resulting end-to-end delay (excluding propagation delay) can be smaller than the video frame period, which is better than what can be obtained with circuit switching View full abstract»

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  • Optimal PNNI complex node representations for restrictive costs and minimal path computation time

    Page(s): 493 - 506
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (392 KB)  

    The private network-to-network interface (PNNI) protocol, which specifies how topology information is to be distributed in an ATM network, allows ATM switches to be aggregated into clusters called peer groups. Outside of a peer group its topology is aggregated into a single logical node. This method can be applied recursively so that PNNI can hierarchically aggregate network topology state information. To provide good accuracy in choosing optimal paths in a PNNI network, the PNNI standard provides a way to represent a peer group with a structure called the complex node representation. It allows the cost of traversing the peer group between any ingress and egress to be advertised in a compact form. Complex node representations using a small number of links result in a correspondingly short path computation time and therefore in good performance. It is, therefore, desirable that the complex node representation contains as few links as possible. This paper considers the class of complex node representations for which the path computation time is minimal. It assumes that the path selection is based on restrictive costs, such as bandwidth, and considers the symmetric case. It presents a method for constructing the set of the optimal complex node representations in the sense that they use the minimum possible number of links. Central to the development of this method is the establishment of the optimal substructure property of the optimal complex node representations View full abstract»

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  • Video staging: a proxy-server-based approach to end-to-end video delivery over wide-area networks

    Page(s): 429 - 442
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (428 KB)  

    Real-time distribution of stored video over wide-area networks (WANs) is a crucial component of many emerging distributed multimedia applications. The heterogeneity in the underlying network environments is an important factor that must be taken into consideration when designing an end-to-end video delivery system. We present a novel approach to the problem of end-to-end video delivery over WANs using proxy servers situated between local-area networks (LANs) and a backbone WAN. A major objective of our approach is to reduce the backbone WAN bandwidth requirement. Toward this end, we develop an effective video delivery technique called video staging via intelligent utilization of the disk bandwidth and storage space available at proxy servers. Using this video staging technique, only part of a video stream is retrieved directly from the central video server across the backbone WAN whereas the rest of the video stream is delivered to users locally from proxy servers attached to the LANs. In this manner, the WAN bandwidth requirement can be significantly reduced, particularly when a large number of users from the same LAN access the video data. We design several video staging methods and evaluate their effectiveness in trading the disk bandwidth of a proxy server for the backbone WAN bandwidth. We also develop two heuristic algorithms to solve the problem of designing a multiple video staging scheme for a proxy server with a given video access profile of a LAN. Our results demonstrate that the proposed proxy-server-based approach provides an effective and scalable solution to the problem of the end-to-end video delivery over WANs View full abstract»

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  • On nonblocking multicast three-stage Clos networks

    Page(s): 535 - 539
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (124 KB)  

    We give necessary and sufficient conditions for strictly nonblocking three-stage Clos (1953) networks with two types of multicast traffic. Then, we extend the results to other models where the routing is under certain restrictions. Finally, we compare our results with existing literature to mark the differences and similarities View full abstract»

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  • Application-layer anycasting: a server selection architecture and use in a replicated Web service

    Page(s): 455 - 466
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (208 KB)  

    Server replication improves the ability of a service to handle a large number of clients. One of the important factors in the efficient utilization of replicated servers is the ability to direct client requests to the “best” server, according to some optimality criteria. In the anycasting communication paradigm, a sender communicates with a receiver chosen from an anycast group of equivalent receivers. As such, anycasting is well suited to the problem of directing clients to replicated servers. This paper examines the definition and support of the anycasting paradigm at the application-layer, providing a service that uses an anycast resolver to map an anycast domain name and a selection criteria into an IP address. By realizing anycasting in the application-layer, we achieve flexibility in the optimization criteria and ease the deployment of the service. As a case study, we examine the performance of our system for a key service: replicated Web servers. To this end, we develop an approach for estimating the response time that a client will experience when accessing given servers. Such information is maintained in the anycast resolver that clients query to obtain the identity of the server with the best estimated response time. Our performance collection technique combines server push with resolver probes to estimate the expected response time without undue overhead. Our experiments show that selecting a server using our architecture and estimation technique can improve the client response time by a factor of two over nearest server selection and by a factor of four over random server selection View full abstract»

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  • An efficient cell-scheduling algorithm for multicast ATM switching systems

    Page(s): 517 - 525
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (256 KB)  

    We propose an efficient multicast cell-scheduling algorithm, called multiple-slot cell-scheduling algorithm, for multicast ATM switching systems with input queues. Cells in an input-queueing system are usually served based on the first-in-first-out (FIFO) discipline, which may have a serious head-of-line (HOL) blocking problem. Our algorithm differs from previous algorithms in that we consider the output contention resolution for multiple time slots instead of the current time slot only. Like a window-based scheduling algorithm, our algorithm allows cells behind an HOL cell to be transmitted prior to the HOL cell in the same input port. Thus, HOL blocking can be alleviated. We have illustrated that the delay-throughput performance of our algorithm outperforms most of those algorithms that consider only the output contention resolution for the current time slot. We also present a simple and efficient architecture for realizing our algorithm, which can dramatically reduce the time complexity. We believe that the proposed architecture is very suitable for multicast asynchronous transfer mode (ATM) switching systems with input queues View full abstract»

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  • Real-time estimation of the parameters of long-range dependence

    Page(s): 467 - 478
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (236 KB)  

    An on-line version of the Abry-Veitch (see IEEE GLOBECOM'98, Sydney, Australia,p.3716-21, 1998) wavelet-based estimator of the Hurst parameter is presented. It has very low memory and computational requirements and scales naturally to arbitrarily high data rates, enabling its use in real-time applications such as admission control, and avoiding the need to store huge data sets for off-line analysis. The performance of the estimator as a function of the length of data processed is demonstrated using simulated data. An implementation for 10-Mb/s Ethernet based on standard hardware supporting sampling rates of 1 data point per millisecond is described, and results of its operation presented, as is an implementation for 155-Mb/s asynchronous transfer mode networks. Finally we illustrate the power of on-line measurements by collecting measurements over a period of five months, and using them to look for diurnal trends in scaling properties of the data View full abstract»

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  • Key management for restricted multicast using broadcast encryption

    Page(s): 443 - 454
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (292 KB)  

    The problem we address is how to communicate securely with a set of users (the target set) over an insecure broadcast channel. This problem occurs in two application domains: satellite/cable pay TV and the Internet MBone. In these systems, the parameters of major concern are the number of key transmissions and the number of keys held by each receiver. In the Internet domain, previous schemes suggest building a separate key tree for each multicast program, thus incurring a setup cost of at least k log k per program for target sets of size k. In the pay TV domain, a single key structure is used for all programs, but known theoretical bounds show that either very long transmissions are required, or that each receiver needs to keep prohibitively many keys. Our approach is targeted at both domains. Our schemes maintain a single key structure that requires each receiver to keep only a logarithmic number of establishment keys for its entire lifetime. At the same time our schemes admit low numbers of transmissions. In order to achieve these goals, and to break away from the theoretical bounds, we allow a controlled number of users outside the target set to occasionally receive the multicast. This relaxation is appropriate for many scenarios in which the encryption is used to force consumers to pay for a service, rather than to withhold sensitive information. For this purpose, we introduce f-redundant establishment key allocations, which guarantee that the total number of recipients is no more than f times the number of intended recipients. We measure the performance of such schemes by the number of key transmissions they require, by their redundancy f, and by the probability that a user outside the target set (a free-rider) will be able to decrypt the multicast. We prove a new lower bound, present several new establishment key allocations, and evaluate our schemes' performance by extensive simulation View full abstract»

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Aims & Scope

The IEEE/ACM Transactions on Networking’s high-level objective is to publish high-quality, original research results derived from theoretical or experimental exploration of the area of communication/computer networking.

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Meet Our Editors

Editor-in-Chief
R. Srikant
Dept. of Electrical & Computer Engineering
Univ. of Illinois at Urbana-Champaign