A linear-based trunk reservation routing algorithm for ATM networks

In this paper a practical routing algorithm is proposed that increases the network throughput irrespective of the network traffic load. Its effectiveness is based on an efficient cost function which achieves a successful trade-off between the use of the minimum-hop routes and the application of the load-balancing concept. Moreover, it employs the known Trunk Reservation notion according to a probability that increases linearly with the traffic load. This results in an effective compromise of the performance of the algorithm between light and heavy traffic loads. Finally, its simplicity and its suitability for a real-time application render it as an efficient routing algorithm for ATM networks. Copyright © 1999 John Wiley & Sons, Ltd.

Network coding provides a powerful mechanism to improve performance of wireless networks. In this paper, we present a service curve model for performance analysis in wireless network coding. Prior work on wireless network coding mainly focuses on the overall throughput of the network. Our research aims to analyze the performance of each flow in the network. The theoretical basis of our research is network calculus. In order to model network coding in network calculus, we propose a flow-oriented definition of coding opportunity. Based on the definition, we derive formulations for computing the delay and backlog of flows in the network. Numerical results show that network coding can dramatically improve the per-flow performance under heavy traffic load. However, under light traffic load, it makes tiny improvement that may unfortunately be counteracted by the overhead of coding. To guarantee performance gain, we propose the concept of coding enabled area that can help to indicate when to enable the function of network coding in practice.

We analyze a new wormhole routing scheme, which we call the wormhole deflection with virtual channels (abbreviated WDVC) scheme, that combines wormhole routing with virtual channels and deflection routing to provide efficient lossless communication. We use new analytical models to analyze the performance of the WDVC scheme for the Manhattan Street (MS) network topology. In particular, we examine the effect of the traffic load and the number of virtual channels on the throughput and the length of paths followed by the worms, and compare the analytical results obtained with corresponding simulation results. Our results indicate that wormhole deflections combined with virtual channels is efficient under both light and heavy traffic loads, especially when the number of virtual channels on a link is large.

Two quasi-static minimax open shortest path first (OSPF) routing algorithms in networks supporting the Switched Multi-megabit Data Service (SMDS) are presented and compared. In OSPF routing, the network is modeled as a graph and each link is associated with a nonnegative arc weight. A shortest path spanning tree is calculated for each origin to carry both the individually addressed and the group addressed (multicast) traffic. The OSPF routing protocol is adopted as a major part of the default inter-switching system interface (ISSI) routing algorithm for SMDS networks where arc weights are inversely proportional to the aggregate link set capacities. The problem of choosing a set of link set metrics is considered so that the maximum link utilization factor is minimized in an SMDS network. The problem is formulated as a nonlinear mixed integer programming problem.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Wireless Mesh Networks become popular and are used everywhere as an alternative to broadband connections. The ease of configuration of wireless mesh LAN, the mobility of clients, and the large coverage make it attractive choice for supporting wireless technology in LAN and MAN. However, there are some concerns in assigning the multiple channels for different node and having efficient routing algorithm to route packet seamlessly without affecting the network performance. Multiple channel usage has been addressed in previous research paper, but efficient routing algorithm still to be researched. In this paper an efficient seamless non-broadcast routing algorithm has been developed and implemented in C++ to support the wireless mesh network. This algorithm is based on mapping the mesh wireless routing nodes geographically according to 2 coordinates. Each node will apply this algorithm to find the closet neighboring node that leads to destination based on the mapped network without the need for broadcast such as the one used in traditional routing protocol in RIP, and OSPF.

A newly developed evaluation index is proposed to describe anti-rutting performance of Gravel Asphalt Concrete (GAC) mixtures under high temperature and heavy loads. First, the Chinese Wheel Grinding (CWG) test and Accelerated Asphalt Pavement (AAP) test was conducted for different temperatures to determine the crucial temperature of anti-rutting performance of GAC mixtures. Then, the correlation between results from CWG test and AAP test was determined to confirm the validity of using AAP test for further experiments. The relationship between Dynamic Stability (DS) and viscosity of asphalt mixtures as well as traffic loads was also conducted to verify the correlation. Lastly, the fitting results of DS was confirmed based on temperature, traffic loads and viscosity of modified asphalt used in GAC mixtures. The fitting results confirmed that anti-rutting performance of GAC mixtures decreases remarkably when under high temperature and heavy loads.

This paper presents a Constraint-Based Routing (CBR) algorithm for Multiprotocol Label Switching (MPLS) network which is designed for mapping among any layer-2 protocols and any layer-3 protocols of the OSI model. The MPLS network has capability of routing with some specific constraints for supporting desire Quality of Service (QoS). The most important constraint is the demand bandwidth. The efficient routing algorithm should have low percentage of call-setup request blocking, high network utilization and low calculation complexity. There are many previously proposed algorithms such as minimum hop algorithm, widest shortest path algorithm, and minimum interference routing algorithm. In this paper, a new algorithm is proposed. The proposed algorithm is based on the weight calculation of an amounts of paths routed over each links in the network. From the simulation results, the proposed algorithm has well performance over high network utilization, low blocking percentage and low complexity.

A scheme for integrated service on multiple-access broadcast networks (MABNs) based on the superchannel concept is proposed, and a protocol for voice/data integration is described. The superchannel is a logical channel which is established on existing MABNs, and each channel can carry a different type of traffic under a special control protocol. The scheme is fully compatible with existing MABNs. For example, data stations can operate using their original protocol. By introducing a priority boundary, the channel utilization is improved under heavy voice traffic and light data load, while still maintaining a desired level of performance if the combined voice/data traffic load is heavy. Since interference of voice and data traffic only appears at the boundary of the superchannel cycle, the protocol can be relatively easily extended for multiple traffic types. >

Conventionally it has been presumed that heavy traffic loading is the main driver that causes pavements to reach its limiting performance criteria such as fatigue and permanent deformation, and as a result, pavement designs have primarily only incorporated traffic loading. However, close monitoring of pavements has revealed that in fact, traffic loading alone may not create the conditions that lead to sudden failure of pavements. One aspect that is often not directly included in pavement design is the climatic factors, specifically temperature and moisture variations of the pavement soil. The occurrence of climatic extremes is becoming ever so frequent and there is a pressing need to better understand the effects of these extreme climatic conditions on pavement performance. This study presents the findings of an investigation into the effects of moisture and environmental conditions on the mechanical behaviour of granular pavements. The study was conducted with the aim of determining how seasonal effects from hot and wet climatic conditions impact on the sudden failure of pavements. Data was collected from state-of-the-art instrumentation on two field pavement sites located in Sunshine Coast, Australia. The sites were monitored over three years, and variations in daily temperature, moisture and strain values were analysed. Cyclic strain variations were observed in a cemented pavement basecourse layer where large fatigue tensile strains were present when moisture increased and temperature decreased. The results indicate that as moisture rises and temperature falls, critical fatigue strain increase above the fatigue endurance limit. This occurs when moisture was at or above optimum moisture content and surface layer temperature was between 38°C and 31°C. The data indicated that the change in pore pressure as a result of moisture and temperature variations within the granular basecourse soil were causing the strains in the pavement. Heavy traffic volume only had a minor effect on basecourse strain although the combined effect of soil moisture, temperature and heavy traffic loading was a cause for large fatigue strains in the pavement.

In position-based routing algorithms for ad-hoc networks, the nodes use the geographical information to make the routing decisions. Recent research in this field primarily addresses such routing algorithms in two dimensional space (2D). However, in real applications, nodes may be distributed in 3D space. In this paper we extend previous randomized routing algorithms from 2D space to 3D space, and we propose two new position-based routing algorithms that combine randomized AB3D routing algorithms with a deterministic CFace (coordinate face) algorithm. The first algorithm AB3D-CFace(1)-AB3D starts with AB3D routing algorithm until a local minimum is reached. The algorithm then switches to CFace routing using one projected coordinate. IfCFace(l) enters a loop, the algorithm switches back to AB3D. The second algorithm AB3D-CFace(3) starts with AB3D, until a local minimum is reached. The algorithm then permanently switches to CFace routing using three projected coordinates, in order. We evaluate our mechanisms and compare them with the current routing algorithms. The simulation results show the significant improvement in delivery rate over pure AB3D randomized routing (97% compared to 70%) and reduction in path dilation (up to 50%) over pure CFace algorithm.

We study end-to-end delay performance of different routing algorithms in networks with random failures. Specifically, we compare delay performances of differential backlog (DB) and shortest path (SP) routing algorithms and show that DB routing outperforms SP routing in terms of throughput when the network is heavily loaded and/or the failure rate is high while SP routing achieves better delay performance in the low load regime. Then, we investigate delay performance of a hybrid routing algorithm that combines principles of both SP and DB routing algorithms and show that it outperforms both of these routing algorithms. Finally, we demonstrate improvements in delay performance of DB routing through the use of a digital fountain approach which was originally proposed for multicast applications. In addition, our results show that there exists an optimal coding rate where digital fountain based DB routing achieves minimum end-to-end delay. To the best of our knowledge, this is the first work which investigates delay performance of DB routing and its enhanced versions for networks with link failures.

Randomized self-routing algorithms for Clos networks

In the last few years, Network-on-Chip (NoC) has emerged as a dominant paradigm for synthesis of a multi-core Systems-on-Chip (SoC). A future NoC architecture must be general enough to allow volume production and must have features for specialization and configuration to match and meet the application’s power and performance requirements. This chapter describes how one important aspect, namely the routing algorithm, can be optimized in such NoC platforms. Routing algorithm has a major effect on the performance (packet latency and throughput) as well as power consumption of NoC. A methodology to develop efficient and deadlock free routing algorithms which are specialized for an application or a set of concurrent applications is presented. The methodology, called application-specific routing algorithms (APSRA), exploits the application-specific information regarding pairs of cores which communicate and other pairs which never communicate in the NoC platform. This information is used to maximize the adaptivity of the routing algorithm without compromising the important property of deadlock freedom. The chapter also presents an extensive comparison between the routing algorithms generated using APSRA methodology and general purpose deadlock-free routing algorithms. The simulation-based evaluations are performed using both synthetic traffic and traffic from real applications. The comparison embraces several performance indices such as degree of adaptiveness, average delay, throughput, power dissipation, and energy consumption. In spite of an adverse impact on router architecture, it is shown that the higher adaptivity of APSRA leads to significant improvements in both routing performance and energy consumption.

Most works about all-optical circuit-switched WDM networks considers a shortest path algorithm for fixed routing, like the Dijkstra’ algorithm. However, recently, two new algorithms, searching for better load balancing and presenting superior performance than Dijkstra´s when submitted to an uniform traffic load, were proposed, the Restricted Routing Technique (RRT) and the Best among the Shortest Routes - (BSR). This work evaluates the performance of these algorithms under a non-uniform traffic load. For each topology studied were observed specific characteristics of the impact of the non-uniform traffic load for each routing algorithm. Overall, performance evaluation results showed that the algorithm BSR achieves for all topologies studied superior performance in terms of blocking probability and fairness.

Data centers play an important role in today's Internet development. Research to find scalable architecture and efficient routing algorithms for data center networks has gained popularity. The fat-tree architecture, which is essentially a folded version of a Clos network, has proved to be readily implementable and is scalable. In this paper, we investigate routing on a fat-tree network by deriving its global packing number and by presenting explicit algorithms for the construction of optimal, load-balanced routing solutions. Consider an optical network that employs wavelength division multiplexing in which every user node sets up a connection with every other user node. The global packing number is basically the number of wavelengths required by the network to support such a traffic load, under the restriction that each source-to-destination connection is assigned a wavelength that remains constant in the network. In mathematical terms, consider a bidirectional, simple graph, G and let N ⊆ V(G) be a set of nodes. A path system P of G with respect to N consists of |N|(|N| -1) directed paths, one path to connect each of the source-destination node pairs in N. The global packing number of a path system P, denoted by Φ(G, N, P), is the minimum integer k to guarantee the existence of a mapping φ : P → (1, 2, ..., k), such that φ(P) ≠ φ(P̅) if P and P̅ have common arc(s). The global packing number of (G, N), denoted by Φ(G, N), is defined to be the minimum Φ(G, N, P) among all possible path systems ?. In additional to wavelength division optical networks, this number also carries significance for networks employing time division multiple access. In this paper, we compute by explicit route construction the global packing number of (T <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">n</sub> , N), where T <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">n</sub> denotes the topology of the n-ary fat-tree network, and N is considered to be the set of all edge switches or the set of all supported hosts. We show that the constructed routes are load-balanced and require minimal link capacity at all network links.