State-dependent dynamic traffic management for telephone networks
TL;DR: The main design considerations are reviewed, focusing on the update cycle, protective allowance, multiple alternate routes, congestion-control thresholds, and algorithm extensions.
Abstract: Dynamic traffic management (DTM) is described. The overall system architecture and data flow, routing, and congestion control are addressed. The main design considerations are reviewed, focusing on the update cycle, protective allowance, multiple alternate routes, congestion-control thresholds, and algorithm extensions. The immediate benefits that automation and near-real-time responsiveness entail in traffic management are outlined. These lie in the areas of capital savings, traffic management automation, and trunk servicing. >
Citations
More filters
TL;DR: A call architecture that may be used for QOS matching and a connection management mechanism for network resource allocation and a new rule-based, call-by-call source routing strategy for integrated communication networks are presented.
Abstract: With increasingly diverse QOS requirements, it is impractical to continue to rely on conventional routing paradigms that emphasize the search for an optimal path based on a predetermined metric, or a particular function of multiple metrics. Modern routing strategies must not only be adaptive to network changes but also offer considerable economy of scope. We consider the problem of routing in networks subject to QOS constraints. After providing an overview of prior routing work, we define various QOS constraints. We present a call architecture that may be used for QOS matching and a connection management mechanism for network resource allocation. We discuss fallback routing, and review some existing routing frameworks. We also present a new rule-based, call-by-call source routing strategy for integrated communication networks. >
242 citations
Patent•
AT&T1
TL;DR: In this paper, a network management node collects trunk loading data and switch congestion data from switches in a telecommunication system and compares them to yield potential intermediate switch candidates having the lowest available load and switches with the lowest congestion consistent with other constraints associated with intermediate switch selection.
Abstract: A network management node (10) collects trunk loading data and switch congestion data from switches in a telecommunication system. Path loading vectors (52, 56,) constraint vector (66), and switch congestion vector (76) are calculated and compared to yield potential intermediate switch candidates having the lowest available, trunk traffic loading and switches with the lowest congestion consistent with other constraints associated with intermediate switch selection. Trunk groups with increasing levels of traffic and switches with increasing levels of congestion are incrementally tested in order to yield potential intermediate switch candidates whereby call distribution to the lightest loaded trunks and switches is accomplished.
139 citations
Patent•
26 Oct 1994TL;DR: In this article, the authors describe a dynamic controlled routing (DCR) network, which is formed by a plurality of network switching elements, each connected to at least one other by at least a circuit group for carrying calls there between, and a network processor connected to the network elements by data links.
Abstract: A dynamically controlled routing (DCR) telecommunications network is formed by a plurality of network switching elements, each connected to at least one other by at least one circuit group for carrying calls therebetween, and a network processor connected to the network elements by data links. Each network switching element determines, for each call, a neighboring network element to which it should be routed. It does so by accessing a routing table which contains alternate routes to be attempted if a direct route either does not exist or cannot be used. The routing tables are updated periodically by the network controller. The DCR network functions as a group of nodes interconnected by links and routing takes place on a node-to-node basis. At least one of the nodes is a logical entity which does not necessarily have a direct correspondence to a single physical network element but rather corresponds to a group of at least one physical component which may be a network element, a part of a network element, or a plurality of network elements or parts thereof. Likewise, a link to the virtual node does not necessarily correspond to a circuit group but comprises the set of direct circuit groups connecting to the components of the virtual node. DCR networks employing virtual nodes have increased flexibility. For example, final destinations outside the DCR network can be associated with the virtual node ifs an intermediate destination node, thereby allowing a call to exit the DCR network via any of the components of the virtual node rather than via only one Unique Exit Gateway.
78 citations
Patent•
11 Mar 1998TL;DR: In this article, the authors propose a dynamic routing of a call in an intelligent telecommunications network, where a first switching unit responds to a destination address in a call to attempt a direct link to a neighbouring switching unit and, in the event that the attempt is unsuccessful, issues to the central computer unit a message containing the destination address.
Abstract: An "Intelligent" telecommunications network comprises a plurality of switching units interconnected by links, and connected to a central computer unit by a data communication system. For dynamic routing of a call, a first switching unit responds to a destination address in a call to attempt a direct link to a neighbouring switching unit and, in the event that the attempt is unsuccessful, issues to the central computer unit a message containing the destination address. The central computer unit uses the destination address to identify the unsuccessful link; (ii) updates a routing database to identify the link as unavailable; (iii) determines an alternative route for the call using a tandem node and (iv) compiles a return message including a network address for a tandem switching unit and transmits it to the first switching unit. The latter attempts to route the call via a link to the tandem unit which attempts to complete the call by a direct link to the destination switching unit. The tandem node switching unit also queries the central computer if it cannot complete the call by a direct link to the destination switching unit, whereupon the central computer will set to zero the idleness of the direct link which the tandem unit attempted and then determine an alternate route from the tandem unit to the destination, i.e. with the idleness factors of both direct links set to zero, resulting in an alternate route having three links.
59 citations
TL;DR: This paper presents an original analysis of an LLR-based rerouting scheme and through numerical examples and confirmation by computer simulation, the throughput gain of rerouted is established.
Abstract: Dynamic routing has been adopted in circuit-switched networks in many parts of the world. Most of the routing algorithms used are least loaded routing (LLR) based for its simplicity and efficiency. Rerouting is the practice of routing calls on alternate paths back to direct paths or to other less congested alternate paths. It allows the continuous redistribution of network loads for the relief of the congestion on direct paths. In this paper, we present an original analysis of an LLR-based rerouting scheme. Through numerical examples and confirmation by computer simulation, the throughput gain of rerouting is established.
58 citations
References
More filters
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: The analysis of comparably engineered hierarchical networks shows that these networks do not exhibit a drop in carried load under overloads (in the absence of switching system dynamics), and it is shown that using trunk reservation for first-routed traffic allows the formulation of a control strategy that provides a high level of network carried load during overloads.
Abstract: We report the results of a study of the performance of engineered nonhierarchical and hierarchical routing networks under overloads. This study was motivated by results obtained from mathematical models for small, symmetric, uniformly loaded, nonhierarchical networks with transparent switching systems, showing the existence of network instabilities. We extend the mathematical models to more general nonhierarchical networks, and show with analysis and an extant simulation model that such instabilities are also found in nonsymmetric, nonhierarchical networks. We then use our models to consider whether engineered nonhierarchical networks exhibit such unstable behavior. No instabilities are found in the engineered nonhierarchical networks considered here. However, the nonhierarchical networks consistently demonstrate a drop in carried load between 10- and 15-percent overloads. Our analysis of comparably engineered hierarchical networks shows that these networks do not exhibit a drop in carried load under overloads (in the absence of switching system dynamics). Finally, we show that using trunk reservation for first-routed traffic allows the formulation of a control strategy that provides a high level of network carried load during overloads.
187 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: The simulation is used to highlight the significance of network structure, signalling techniques, multiple overflows and update cycle length for the efficiency of a flexible routing rule.
Abstract: The presented paper is concerned with qualitative and quantitative analysis of advanced traffic control concepts. In the first part a survey of traffic control techniques is made with the final aim of separating the factors influencing the network grade of service. The second part is devoted to the performance evaluation of adaptive routing in two trial networks. The simulation is used to highlight the significance of network structure, signalling techniques, multiple overflows and update cycle length for the efficiency of a flexible routing rule.
29 citations
Proceedings Article•
01 Jan 1988
TL;DR: A state-dependent call routing strategy for circuit-switched networks, based on maximization of total revenue from the network is presented, which shows that by controlling revenue factors several different objectives can be achieved, ego network traffic maximization, revenue maximized, priority for a certain call class, decreasing blocking for handicapped calls.
Abstract: In the paper a state-dependent call routing strategy for circuit-switched networks, based on maximization of total revenue from the network is presented. The optimal decision whether to accept a new call or not and which path to select depends upon the p:redicted values of net-gains from carrying this call on accessible paths. Th~ net-gains take into account the possibility of carrying other calls instead of the one just offered. An analytical model is given to evaluate net-gains. Performance of an impleme~tation of this routing scheme is evaluated by a simulation study including comparisons with other existing routing strategies. The advantage of the presented approach is that by controlling revenue factors several different objectives can be achieved, ego network traffic maximization, revenue maximization, priority for a certain call class, decreasing blocking for handicapped calls.
25 citations