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Networking, IEEE/ACM Transactions on

Issue 1 • Date Feb. 2002

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Displaying Results 1 - 13 of 13
  • Editorial

    Page(s): 1
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    Freely Available from IEEE
  • Scalable flow control for multicast ABR services in ATM networks

    Page(s): 67 - 85
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (690 KB) |  | HTML iconHTML  

    We propose a flow-control scheme for multicast ABR services in ATM networks. At the heart of the proposed scheme is an optimal second-order rate control algorithm, called the α-control, designed to deal with the variation in RM-cell round-trip time (RTT) resulting from dynamic drift of the bottleneck in a multicast tree. Applying two-dimensional rate control, the proposed scheme makes the rate process converge to the available bandwidth of the connection's most congested link sensed by the traffic source. It also confines the buffer occupancy to a target regime bounded by a finite buffer capacity as the system enters the equilibrium state. It works well irrespective of the topology of the multicast tree. Using the fluid analysis, we model the proposed scheme and analyze the system dynamics for multicast ABR traffic. We study the convergence properties and derive the optimal-control conditions for the α-control. The analytical results show that the scheme is stable and efficient in the sense that both the source rate and bottleneck queue length rapidly converge to a small neighborhood of the designated operating point. We present simulation results which verify the analytical observations. The simulation experiments also demonstrate the superiority of the proposed scheme to the other schemes in dealing with RM-cell RTT and link-bandwidth variations, achieving fairness in both buffer and bandwidth occupancies, and enhancing average throughput View full abstract»

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  • Performance issues in WWW servers

    Page(s): 2 - 11
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (194 KB) |  | HTML iconHTML  

    This paper evaluates techniques for improving operating system and network protocol software support for high-performance World Wide Web servers. We study approaches in three categories: i.e., new socket functions, per-byte optimizations, and per-connection optimizations. We examine two proposed socket functions, i.e., acceptex( ) and send-file( ), comparing send-file( )'s effectiveness with a combination of mmap( ) and writev( ). We show how send-file( ) provides the necessary semantic support to eliminate copies and checksums in the kernel, and quantify the benefit of the function's header and close options. We also present mechanisms to reduce the number of packets exchanged in an HTTP transaction, both increasing server performance and reducing network utilization, without compromising interoperability. Results using WebStone show that our combination of mechanisms can improve server throughput by up to 64%, and can eliminate up to 33% of the packets in an HTTP exchange. Results with SURGE show an aggregate increase in server throughput of 25% View full abstract»

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  • A framework for guaranteeing statistical QoS

    Page(s): 27 - 42
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (343 KB) |  | HTML iconHTML  

    Continuous-media traffic (i.e., audio and video) can tolerate some loss but have rigid delay constraints. A natural QoS requirement for a continuous-media connection is a prescribed limit on the fraction of traffic that exceeds an end-to-end delay constraint. We propose and analyze a framework that provides such a statistical QoS guarantee to traffic in a packet-switched network. Providing statistical guarantees in a network is a notoriously difficult problem because traffic flows lose their original statistical characterizations at the outputs of queues. Our scheme uses bufferless statistical multiplexing combined with cascaded leaky buckets for smoothing and traffic contracting. This scheme along with a novel method for bounding the loss probability gives a tractable framework for providing end-to-end statistical QoS. Using MPEG video traces, we present numerical results that compare the connection-carrying capacity of our scheme with that of guaranteed service schemes (i.e., no loss) using GPS and RCS. Our numerical work indicates that our scheme can support significantly more connections without introducing significant traffic loss View full abstract»

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  • On multicast flow control for heterogeneous receivers

    Page(s): 86 - 101
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (477 KB) |  | HTML iconHTML  

    In this paper, we study the impact of heterogeneous receivers on the throughput of multicast flow control and propose a new multicast flow control algorithm to optimally partition group members into multiple subgroups. Our main contributions are as follows. First, we cast the multicast flow control problem in the Internet as the list partition problem and then prove that the list partition problem is equivalent to the optimal paging problem in cellular networks. The result is not only interesting in itself but also essential to derive the first known analytical bounds for the throughput of multicast flow control. Furthermore, we propose an algorithm to solve not only the list partition problem but also the optimal paging problem and the problem of bulk data transfer using multiple multicast groups. The complexity of our algorithm is one order less than the best known algorithm designed only for the problem of bulk data transfer using multiple multicast groups in the literature. While earlier work uses simulations to justify the usage of multiple subgroups to deliver information to a large amount of receivers in heterogeneous networks, we provide the first analytical support View full abstract»

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  • Generalized loop-back recovery in optical mesh networks

    Page(s): 153 - 164
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (238 KB) |  | HTML iconHTML  

    Current means of providing loop-back recovery, which is widely used in SONET, rely on ring topologies, or on overlaying logical ring topologies upon physical meshes. Loop-back is desirable to provide rapid preplanned recovery of link or node failures in a bandwidth-efficient distributed manner. We introduce generalized loop-back, a novel scheme for performing loop-back in optical mesh networks. We present an algorithm to perform recovery for link failure and one to perform generalized loop-back recovery for node failure. We illustrate the operation of both algorithms, prove their validity, and present a network management protocol algorithm, which enables distributed operation for link or node failure. We present three different applications of generalized loop-back. First, we present heuristic algorithms for selecting recovery graphs, which maintain short maximum and average lengths of recovery paths. Second, we present WDM-based loop-back recovery for optical networks where wavelengths are used to back up other wavelengths. We compare, for WDM-based loop-back, the operation of generalized loop-back operation with known ring-based ways of providing loop-back recovery over mesh networks. Finally, we introduce the use of generalized loop-back to provide recovery in a way that allows dynamic choice of routes over preplanned directions View full abstract»

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  • Loss performance analysis for heterogeneous on-off sources with application to connection admission control

    Page(s): 125 - 138
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (301 KB) |  | HTML iconHTML  

    The bufferless fluid flow model (BFFM) is often used in the literature for loss performance analysis. We propose an efficient and effective means of investigating cell loss using the BFFM. We define the cell loss rate function (CLRF) and use it to characterize the loss performance of traffic sources in the BFFM. Stochastic ordering theory is used to study the CLRF. The introduction of the stochastic ordering theory not only simplifies the theoretical analysis but also makes it possible to extend the scope of applications and theoretical analysis presented. A cell loss upper bound for heterogeneous on-off sources is proposed. The proposed cell loss upper bound is tighter than those previously proposed in the literature. A connection admission control (CAC) scheme using online measurements is designed based on the cell loss upper bound. Extensive simulation is carried out to study the performance of the CAC scheme. Particular attention is paid to the impact of inaccuracies in user-declared traffic parameters on the performance of the CAC scheme. Simulation results indicate that the proposed CAC scheme can ensure QoS guarantee, is robust to inaccuracies in declared traffic parameters, and is capable of achieving high link utilization View full abstract»

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  • Proportional differentiated services: delay differentiation and packet scheduling

    Page(s): 12 - 26
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (337 KB) |  | HTML iconHTML  

    The proportional differentiation model provides the network operator with the 'tuning knobs' for adjusting the per-hop quality-of-service (QoS) ratios between classes, independent of the class loads. This paper applies the proportional model in the differentiation of queueing delays, and investigates appropriate packet scheduling mechanisms. Starting from the proportional delay differentiation (PDD) model, we derive the average queueing delay in each class, show the dynamics of the class delays under the PDD constraints, and state the conditions in which the PDD model is feasible. The feasibility model of the model can be determined from the average delays that result with the strict priorities scheduler. We then focus on scheduling mechanisms that can implement the PDD model, when it is feasible to do so. The proportional average delay (PAD) scheduler meets the PDD constraints, when they are feasible, but it exhibits a pathological behavior in short timescales. The waiting time priority (WTP) scheduler, on the other hand, approximates the PDD model closely, even in the short timescales of a few packet departures, but only in heavy load conditions. PAD and WTP serve as motivation for the third scheduler, called hybrid proportional delay (HPD). HPD approximates the PDD model closely, when the model is feasible, independent of the class load distribution. Also, HPD provides predictable delay differentiation even in short timescales View full abstract»

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  • Error spreading: a perception-driven approach to handling error in continuous media streaming

    Page(s): 139 - 152
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (368 KB) |  | HTML iconHTML  

    With the growing popularity of the Internet, there is increasing interest in using it for audio and video transmission. Perceptual studies of audio and video viewing have shown that viewers find bursty losses, mostly caused by congestion, to be the most annoying disturbance, and hence these are critical issues to be addressed for continuous media streaming applications. Classical error handling techniques have mostly been geared toward ensuring that the transmission is correct, with no attention to timeliness. For isochronous traffic like audio and video, timeliness is a key criterion, and given the high degree of content redundancy, some loss of content is quite acceptable. We introduce the concept of error spreading, which is a transformation technique that permutes the input sequence of packets (from a continuous stream of data) before transmission. The packets are unscrambled at the receiving end. The transformation is designed to ensure that bursty losses in the transformed domain get spread all over the sequence in the original domain, thus improving the perceptual quality of the stream. Our error spreading idea deals with both cases where the stream has or does not have inter-frame dependencies. We next describe a continuous media transmission protocol and experimentally validate its performance based on this idea. We also show that our protocol can be used complementary to other error handling protocols View full abstract»

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  • Optimal partition of QoS requirements on unicast paths and multicast trees

    Page(s): 102 - 114
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (299 KB) |  | HTML iconHTML  

    We investigate the problem of optimal resource allocation for end-to-end QoS requirements on unicast paths and multicast trees. Specifically, we consider a framework in which resource allocation is based on local QoS requirements at each network link, and associated with each link is a cost function that increases with the severity of the QoS requirement. Accordingly, the problem that we address is how to partition an end-to-end QoS requirement into local requirements, such that the overall cost is minimized. We establish efficient (polynomial) solutions for both unicast and multicast connections. These results provide the required foundations for the corresponding QoS routing schemes, which identify either paths or trees that lead to minimal overall cost. In addition, we show that our framework provides better tools for coping with other fundamental multicast problems, such as dynamic tree maintenance View full abstract»

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  • The impact of point-to-multipoint traffic concentration on multirate networks design

    Page(s): 115 - 124
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (176 KB) |  | HTML iconHTML  

    We consider the problem of multirate network design with point-to-multipoint communications. We give a mathematical formulation for this problem. Using approximations, we show that traffic concentration on a small number of links significantly reduces the cost of the network. We then propose a heuristic based on the traffic concentration principle to solve the network design problem approximately. Because this heuristic no longer requires advanced knowledge of demand matrices, we explain how it can be used as the basis for real-time design procedures. By means of numerical results, we show that this heuristic yields nearly optimal solutions View full abstract»

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  • QoS-aware multicast routing for the Internet: the design and evaluation of QoSMIC

    Page(s): 54 - 66
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (203 KB) |  | HTML iconHTML  

    One of the main problems of the current Internet infrastructure is its inability to provide services at consistent quality-of-service (QoS) levels. At the same time, many emerging Internet applications, such as teleeducation, and teleconferencing, require multicast protocols that will provide the necessary QoS. In this paper, we propose QoSMIC, a multicast routing protocol for the Internet, that provides QoS-sensitive paths in a scalable, resource-efficient, and flexible way. QoSMIC differs from the previous protocols in that it identifies multiple paths and selects the one that can provide the required QoS. Two other key advantages of QoSMIC are its flexibility and adaptivity. First, the distribution tree does not have to be rooted at a preselected core router. Second, we can tradeoff between efficiency metrics depending on our needs; for example, we can tradeoff routing efficiency for a reduction in the control messages. Extensive simulations show that our protocol improves the resources utilization and the end-to-end performance compared to the current protocols. Specifically, our protocol reduces the call blocking probability by a factor of six and reduces the end-to-end delay by as much as 90% compared to the PIM protocol View full abstract»

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  • Preserving quality of service guarantees in spite of flow aggregation

    Page(s): 43 - 53
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    We investigate how quality of service may be guaranteed to a flow of packets in the presence of flow aggregation. For efficiency, multiple flows, known as the constituent flows, are merged together resulting in a single aggregate flow. After the network node where the aggregation occurs, packet schedulers are aware of the aggregate flow, but are unaware of its constituent flows. In spite of this, we show that quality of service may be guaranteed to the constituent flows, provided the aggregation is performed fairly. When the delay bound of a flow is de-coupled from the flow's reserved rate, flow aggregation preserves the delay bound. When the delay bound of a flow is coupled to the flow's reserved rate, flow aggregation preserves, and in some cases improves, the delay bound 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.

Full Aims & Scope

Meet Our Editors

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