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Networking, IEEE/ACM Transactions on

Issue 6 • Date Dec. 2001

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Displaying Results 1 - 15 of 15
  • Author index

    Page(s): 845 - 847
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    Freely Available from IEEE
  • Subject index

    Page(s): 847 - 855
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    Freely Available from IEEE
  • A distributed overload control algorithm for delay-bounded call setup

    Page(s): 780 - 789
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (214 KB) |  | HTML iconHTML  

    As communication networks provide newer services, signaling is becoming more and more compute intensive compared to present day networks. It is known that under overload conditions, the call throughput (goodput) and the network revenue drops to zero even when transport resources are available. A distributed overload control algorithm for delay-bounded call setup is proposed. The end-to-end delay bound is budgeted among the switching nodes involved in call setup, and these nodes apply a local overload control with a deterministic delay threshold and drop call requests experiencing higher delays. This algorithm does not depend on feedback on network conditions and makes use of only parameters that can be instrumented locally by the switching node. Using an M/M/1 queueing model with first-in-first-out (FIFO) service discipline at a switching node, two optimized control schemes are considered for local overload control and compared their performance through analysis: one with arrival rate limit and the other with buffer size limit. Though both the schemes minimize the unproductive call processing at heavy load, the latter is found to yield higher call throughput and lower average call setup delays compared to the former. Also, the buffer size required for the scheme with buffer size limit is typically small and call throughput close to the server capacity can be achieved during overload. The performance of the distributed overload control algorithm in a network is evaluated through simulation experiments, using the scheme with buffer size limit for the local overload control. It shows that the average end-to-end delay could be much less than the end-to-end delay bound, providing room for overprovisioning of the delay bounds. The tradeoff between the number of nodes, call throughput, and average end-to-end delay needs to be considered while deciding the route budgeting the end-to-end delay bound among different nodes along the route. These performance results are expected to serve as lower bounds to more sophisticated local call rejection mechanisms such as push-out or time-out along with a last-in-first-out (LIFO) service discipline View full abstract»

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  • Distributed admission control for power-controlled cellular wireless systems

    Page(s): 790 - 800
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (214 KB) |  | HTML iconHTML  

    It is well known that power control can help to improve spectrum utilization in cellular wireless systems. However, many existing distributed power control algorithms do not work well without an effective connection admission control (CAC) mechanism, because they could diverge and result in dropping existing calls when an infeasible call is admitted. In this work, based on a system parameter defined as the discriminant, we propose two distributed CAC algorithms for a power-controlled system. Under these CAC schemes, an infeasible call is rejected early, and incurs only a small disturbance to existing calls, while a feasible call is admitted and the system converges to the Pareto optimal power assignment. Simulation results demonstrate the performance of our algorithms View full abstract»

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  • Stable Internet routing without global coordination

    Page(s): 681 - 692
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    The Border Gateway Protocol (BGP) allows an autonomous system (AS) to apply diverse local policies for selecting routes and propagating reachability information to other domains. However, the BGP permits ASs to have conflicting policies that can lead to routing instability. This paper proposes a set of guidelines for an AS to follow in setting its routing policies, without requiring coordination with other ASs. Our approach exploits the Internet's hierarchical structure and the commercial relationships between ASs to impose a partial order on the set of routes to each destination. The guidelines conform to conventional traffic-engineering practices of ISPs, and provide each AS with significant flexibility in selecting its local policies. Furthermore, the guidelines ensure route convergence even under changes in the topology and routing policies. Drawing on a formal model of BGP, we prove that following our proposed policy guidelines guarantees route convergence. We also describe how our methodology can be applied to new types of relationships between ASs, how to verify the hierarchical AS relationships, and how to realize our policy guidelines. Our approach has significant practical value since it preserves the ability of each AS to apply complex local policies without divulging its BGP configurations to others View full abstract»

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  • On the efficiency of multicast

    Page(s): 719 - 732
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    The average number of joint hops in a shortest-path multicast tree from a root to m arbitrary chosen group member nodes is studied. A general theory for all graphs, hence including the graph representation of the Internet, is presented which quantifies the multicast reduction in network links compared to m times unicast. For two special types of graphs, the random graph Gp(N) and the k-ary tree, exact and asymptotic results are derived. Comparing these explicit results with previously published Internet measurements indicates that the number of routers in the Internet that can be reached from a root grows exponentially in the number of hops with an effective degree of approximately 3.2 View full abstract»

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  • Resource sharing for replicated synchronous groupware

    Page(s): 833 - 843
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (343 KB) |  | HTML iconHTML  

    We describe problems associated with accessing data resources external to the application, which we term externalities, in replicated synchronous collaborative applications. Accessing externalities such as files, databases, network connections, environment variables, and the system clock is not as straightforward in replicated collaborative software as in single-user applications or centralized collaborative systems. We describe ad hoc solutions that add to development cost and complexity because the developer must program different behavior for different replicas. We introduce a novel general approach to accessing externalities uniformly in a replicated collaborative system. The approach uses a semireplicated architecture where the actual externality resides at a single location and is accessed via replicated proxies. This approach allows developers of replicated synchronous groupware to (1) use similar externality access mechanisms as in traditional single-user applications, and (2) program all replicas to execute the same behavior. We describe a general design for proxied access to read-only, write-only, and read-write externalities and discuss the tradeoffs of this semireplicated approach over full, literal replication and the class of applications to which this approach can be successfully applied. We also describe details of a prototype implementation of this approach within a replicated collaboration-transparency system, called Flexible JAMM (Java Applets Made Multiuser) View full abstract»

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  • The jitter time-stamp approach for clock recovery of real-time variable bit-rate traffic

    Page(s): 746 - 754
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    When multimedia streams arrive at the receiver, their temporal relationships may be distorted due to jitter. Assuming the media stream is packetized, the jitter is then the packet's arrival time deviation from its expected arrival time. There are various ways to reduce jitter, which include synchronization at the application layer, or synchronization at the asynchronous transfer mode (ATM) adaptation layer (AAL). The new source rate recovery scheme called jitter time-stamp (JTS) provides synchronization at the ATM adaptation layer 2 (AAL2) which is used to carry variable bit-rate traffic such as compressed voice and video. JTS is implemented, and experiments have shown that it is able to recover the source rate View full abstract»

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  • Routing with a clue

    Page(s): 693 - 705
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (222 KB) |  | HTML iconHTML  

    We suggest a new simple forwarding technique to speed up IP destination address lookup. The technique is a natural extension of IP, requires 5 bits in the IP header (IPv4, 7 in IPv6), and performs IP lookup nearly as fast as IP/Tag switching but with a smaller memory requirement and a much simpler protocol. The basic idea is that each router adds a "clue" to each packet, telling its downstream router where it ended the IP lookup. Since the forwarding tables of neighboring routers are similar, the clue either directly determines the best prefix match for the downstream router, or provides the downstream router with a good point to start its IP lookup. The new scheme thus prevents repeated computations and distributes the lookup process across the routers along the packet path. Each router starts the lookup computation at the point its upstream neighbor has finished. Furthermore, the new scheme is easily assimilated into heterogeneous IP networks, does not require routers coordination, and requires no setup time. Even a flow of one packet enjoys the benefits of the scheme without any additional overhead. The speedup we achieve is about 10 times faster than current standard techniques. In a sense, this paper shows that the current routers employed in the Internet are clue-less; namely, it is possible to speed up the IP lookup by an order of magnitude without any major changes to the existing protocols View full abstract»

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  • New dynamic SPT algorithm based on a ball-and-string model

    Page(s): 706 - 718
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (238 KB) |  | HTML iconHTML  

    A key functionality in today's widely used interior gateway routing protocols such as OSPF and IS-IS involves the computation of a shortest path tree (SPT). In many existing commercial routers, the computation of an SPT is done from scratch following changes in the link states of the network. As there may coexist multiple SPTs in a network with a set of given link states, such recomputation of an entire SPT not only is inefficient but also causes frequent unnecessary changes in the topology of an existing SPT and creates routing instability.. This paper presents a new dynamic SPT algorithm that makes use of the structure of the previously computed SPT. Our algorithm is derived by recasting the SPT problem into an optimization problem in a dual linear programming framework, which can also be interpreted using a ball-and-string model. In this model, the increase (or decrease) of an edge weight in the tree corresponds to the lengthening (or shortening) of a string. By stretching the strings until each node is attached to a tight string, the resulting topology of the model defines an (or multiple) SPT(s). By emulating the dynamics of the ball-and-string model, we can derive an efficient algorithm that propagates changes in distances to all affected nodes in a natural order and in a most economical way. Compared with existing results, our algorithm has the best-known performance in terms of computational complexity as well as minimum changes made to the topology of an SPT. Rigorous proofs for correctness of our algorithm and simulation results illustrating its complexity are also presented View full abstract»

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  • End-to-end congestion control for the Internet: delays and stability

    Page(s): 818 - 832
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (325 KB) |  | HTML iconHTML  

    Under the assumption that queueing delays will eventually become small relative to propagation delays, we derive stability results for a fluid flow model of end-to-end Internet congestion control. The theoretical results of the paper are intended to be decentralized and locally implemented: each end system needs knowledge only of its own round-trip delay. Criteria for local stability and rate of convergence are completely characterized for a single resource, single user system. Stability criteria are also described for networks where all users share the same round-trip delay. Numerical experiments investigate extensions to more general networks. Through simulations, we are able to evaluate the relative importance of queueing delays and propagation delays on network stability. Finally, we suggest how these results may be used to design network resources View full abstract»

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  • Adaptive proportional delay differentiated services: characterization and performance evaluation

    Page(s): 801 - 817
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    We examine a proportional-delay model for Internet differentiated services. Under this model, an Internet service provider (ISP) can control the waiting-time "spacings" between different classes of traffic. Specifically, the ISP tries to ensure that the average waiting time of class i traffic relative to that of class i-1 traffic is kept at a constant specified ratio. If the waiting-time ratio of class i-1 to class i is greater than one, the ISP can legitimately charge users of class i traffic a higher tariff rate (compared to the rate for class i-1 traffic), since class i users consistently enjoy better performance than class i-1 users. To realize such proportional-delay differentiated services, we use the time-dependent priority scheduling algorithm. We formally characterize the feasible regions in which given delay ratios can be achieved. Moreover, a set of control parameters for obtaining the desired delay ratios can be determined by an efficient iterative algorithm. We also use an adaptive control algorithm to maintain the correctness of these parameters in response to changing system load. Experiments are carried out to illustrate the short-term, medium-term and long-term relative waiting-time performances for different service classes under Poisson, Pareto, MMPP and mixed traffic workloads. We also carry out experiments to evaluate the achieved end-to-end accumulative waiting times for different classes of traffic which traverse multiple hops under our service model View full abstract»

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  • On inferring autonomous system relationships in the Internet

    Page(s): 733 - 745
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (236 KB) |  | HTML iconHTML  

    The Internet consists of rapidly increasing number of hosts interconnected by constantly evolving networks of links and routers. Interdomain routing in the Internet is coordinated by the Border Gateway Protocol (BGP). The BGP allows each autonomous system (AS) to choose its own administrative policy in selecting routes and propagating reachability information to others. These routing policies are constrained by the contractual commercial agreements between administrative domains. For example, an AS sets its policy so that it does not provide transit services between its providers. Such policies imply that AS relationships are an important aspect of the Internet structure. We propose an augmented AS graph representation that classifies AS relationships into customer-provider, peering, and sibling relationships. We classify the types of routes that can appear in BGP routing tables based on the relationships between the ASs in the path and present heuristic algorithms that infer AS relationships from BGP routing tables. The algorithms are tested on publicly available BGP routing tables. We verify our inference results with AT&T internal information on its relationship with neighboring ASs. As much as 99.1% of our inference results are confirmed by the AT&T internal information. We also verify our inferred sibling relationships with the information acquired from the WHOIS lookup service. More than half of our inferred sibling-to-sibling relationships are confirmed by the WHOIS lookup service. To the best of our knowledge, there has been no publicly available information about AS relationships and this is the first attempt in understanding and inferring AS relationships in the Internet. We show evidence that some routing table entries stem from router misconfigurations View full abstract»

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  • Polynomial cost approximations in Markov decision theory based call admission control

    Page(s): 769 - 779
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    The problem of call admission control and routing in a multiservice circuit-switched loss network can be solved optimally under certain assumptions by the tools of Markov decision theory. However, in networks of practical size a number of simplifying approximations are needed to make the solution feasible. Assuming link independence, we propose a new method for approximating the state-dependent link costs accurately and relatively efficiently, even on links with extremely large state spaces. The proposed polynomial approximations are optimal in the sense of minimizing the residual in the continuous-time Howard equations of the Markov decision processes associated with the links. Numerical results are presented, and the proposed approximations are found superior to some earlier link-cost approximation methods View full abstract»

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  • Loss probability calculations and asymptotic analysis for finite buffer multiplexers

    Page(s): 755 - 768
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    We propose an approximation for the loss probability, PL(x), in a finite buffer system with buffer size x. Our study is motivated by the case of a high-speed network where a large number of sources are expected to be multiplexed. Hence, by appealing to central limit theorem type of arguments, we model the input process as a general Gaussian process. Our result is obtained by making a simple mapping from the tail probability in an infinite buffer system to the loss probability in a finite buffer system. We also provide a strong asymptotic relationship between our approximation and the actual loss probability for a fairly large class of Gaussian input processes. We derive some interesting asymptotic properties of our approximation and illustrate its effectiveness via a detailed numerical investigation 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