Design and control of networks with dynamic nonhierarchical routing
TL;DR: The evolution of dynamic routing with respect to several future directions is highlighted, including extension to new networks and services, robust design and real-time adaptivity, and extension to interconnecting networks, including the Worldwide Intelligent Network.
Abstract: Dynamic routing concepts are described, and the design and control of dynamic routing networks is discussed. The vastly improved performance of the networks is illustrated with examples from operational experience. The evolution of dynamic routing with respect to several future directions is highlighted. These directions are extension to new networks and services, robust design and real-time adaptivity, and extension to interconnecting networks, including the Worldwide Intelligent Network. >
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24 Jun 1993TL;DR: In this paper, a fallback strategy for a system (700) and method (200) is provided for rerouting a call that fails to be established utilizing a first set of constraints in a communication network system.
Abstract: A fallback strategy for a system (700) and method (200) is provided for rerouting a call that fails to be established utilizing a first set of constraints in a communication network system. This strategy enables the communication network system to utilize a look-around-first type of preemption that avoids unnecessary preemption and provides alternate routing for a call according to predetermined constraints selected by a user.
56 citations
TL;DR: A distributed routing heuristic is proposed to reduce the call blocking rate while preserving a fast call setup time by simulations and shows that the proposed heuristic performs better in most cases than the other two schemes.
Abstract: In this paper, three related virtual channel routing problems on Broadband ISDN are investigated and shown to be NP-complete A distributed routing heuristic is proposed to reduce the call blocking rate while preserving a fast call setup time Various traffic patterns and network topologies are employed to evaluate the performance of the proposed heuristic by simulations Two existing famous routing schemes are also applied for comparison The simulation results show that the proposed heuristic performs better in most cases than the other two schemes
33 citations
32 citations
07 Apr 1991
TL;DR: From their simulation studies, the authors found that with efficient use of trunk group diversity and at a reasonable incremental cost, one can obtain a robust network to respond to a major facility link or a node failure and still meet the network objectives.
Abstract: The authors present traffic restoration design algorithms to attain a robust network for any facility link or node failure. Some of these algorithms were implemented on network models to compute the cost for doing traffic restoration for different traffic restoration level objectives. From their simulation studies, the authors found that with efficient use of trunk group diversity and at a reasonable incremental cost, one can obtain a robust network to respond to a major facility link or a node failure and still meet the network objectives. A similar approach based on the algorithms presented in this work has been proposed for design of the worldwide intelligent network. >
26 citations
References
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TL;DR: In this paper, a theory for permitting direct dialing access to high-delay toll trunk groups is presented, and a method is devised using equivalent random traffic, which has good loss predictive ability under the lost calls cleared assumption, for a diverse field of alternate route trunking arrangements.
Abstract: Present toll trunk traffic engineering practices in the United States are reviewed, and various congestion formulas compared with data obtained on long distance traffic. Customer habits upon meeting busy channels are noted and a theory developed describing the probable result of permitting subscribers to have direct dialing access to high delay toll trunk groups. Continent-wide automatic alternate routing plans are described briefly, in which near no-delay service will permit direct customer dialing. The presence of non-random overflow traffic from high usage groups complicates the estimation of correct quantities of alternate paths. Present methods of solving graded multiple problems are reviewed and found unadaptable to the variety of trunking arrangements occurring in the toll plan. Evidence is given that the principal fluctuation characteristics of overflow-type of non-random traffic are described by their mean and variance. An approximate probability distribution of simultaneous calls for this kind of non-random traffic is developed, and found to agree satisfactorily with theoretical overflow distributions and those seen in traffic simulations. A method is devised using “equivalent random” traffic, which has good loss predictive ability under the “lost calls cleared” assumption, for a diverse field of alternate route trunking arrangements. Loss comparisons are made with traffic simulation results and with observations in exchanges. Working curves are presented by which multi-alternate route trunking systems can be laid out to meet economic and grade of service criteria. Examples of their application are given.
399 citations
TL;DR: An efficient heuristic optimization method is introduced for solution of the LP routing problems, which greatly improves computational speed with minimal loss of accuracy and project computational requirements for a 200-node design problem, which is the estimated size of the intercity Bell System dynamic routing network in the 1990s.
Abstract: The growth of electronic switching systems and the high-capacity interoffice signaling network provide an opportunity to extend telephone network routing rules beyond the conventional hierarchy. Network models are described that illustrate the savings inherent in designing networks for dynamic, nonhierarchical routing. An algorithm for engineering such networks is discussed, and the comparative advantages of various path-routing and progressive-routing techniques are illustrated. A particularly simple implementation of dynamic routing called two-link dynamic routing with crankback is discussed and is shown to yield benefits comparable to much more complicated routing schemes. The efficient solution of embedded linear programming (LP) routing problems is an essential ingredient for the practicality of the design algorithm We introduce an efficient heuristic optimization method for solution of the LP routing problems, which greatly improves computational speed with minimal loss of accuracy. We also project computational requirements for a 200-node design problem, which is the estimated size of the intercity Bell System dynamic routing network in the 1990s.
257 citations
TL;DR: In this paper, the authors illustrate techniques for changing network routing patterns in planned and demand servicing to counteract the effects of forecast errors, and present call-by-call simulation results for real-time routing enhancements to the basic routing algorithms.
Abstract: The design of a network for dynamic routing is made using the forecasted network loads. Load uncertainties arising from errors in the forecast and from daily variations in network load give rise to reserve or idle network capacity not immediately needed by current network demands. The reserve capacity can be reduced by the use of more flexible dynamic routing methods, which allow routing flexibility to help control network flow under load uncertainties. We illustrate techniques for changing network routing patterns in planned and demand servicing to counteract the effects of forecast errors. Included in the benefits are a reduction in both reserve capacity, estimated to be about 5 percent of network first cost, and in trunk rearrangements. We also present call-by-call simulation results for real-time routing enhancements to the basic routing algorithms. The real-time routing algorithms use dynamic trunk reservation techniques, and the simulation results illustrate the improvement in network efficiency and performance under normal daily load variations, network overloads, and network failures.
68 citations
TL;DR: In this article, the Bell System embarked on an extensive study with the purpose of developing a program for operator toll dialing on a nationwide basis, which would handle traffic at high speed between any two points in the United States and Canada, even in the busier hours of the day.
Abstract: In 1945 the Bell System embarked on an extensive study with the purpose of developing a program for operator toll dialing on a nationwide basis. Operator toll dialing had been done, of course, on a limited scale in various parts of the country for many years, but the concept of this program was one of nationwide proportions carried on with a uniform numbering plan∗ arrangement and a completely integrated trunking system which would handle traffic at a high speed between any two points in the United States and Canada, even in the busier hours of the day. Implementation of this program required the development of new switching mechanisms and the exploitation of carrier transmission potentialities to a degree never before achieved. Great strides had already been made in these fields, resulting in the practical development of the coaxial cable system and the first toll crossbar switching office installed at Philadelphia in 1943. But the very core of the nationwide dialing plan was the proposal to revolutionize the method of traffic distribution so as to combine high speed handling over the intertoll trunk network with a highly efficient use of facilities. The method of accomplishing is called “engineered alternate routing”
48 citations
TL;DR: It is shown by example that network integration coupled with flexible routing and bandwidth allocation for preferential treatment of new services provides an effective approach for robust and economical new service provisioning.
Abstract: The authors describe the structure of the worldwide intelligent network (WIN), describe methods for its design and planning, investigate the adequacy of decentralized control for problem-free worldwide call completion, explore the feasibility of adaptive routing and control concepts, discuss network robustness/reliability objectives, and describe a strategy for achieving these objectives for all cooperating international carriers. Several decentralized adaptive routing policies that are particularly attractive in the WIN environment and network performance improvements that can be achieved with the introduction of flexible routing capabilities are characterized. It is shown by example that network integration coupled with flexible routing and bandwidth allocation for preferential treatment of new services provides an effective approach for robust and economical new service provisioning. >
43 citations