Randomized self-routing algorithms for Clos networks

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.

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.

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.

In this paper we study the important problems of message routing, sorting, and selection in a radio network. A radio network consists of stations where each station is a hand-held device. We consider a single-hop radio network. In a single-hop network it is assumed that each station is within the transmission range of every other station. Let RN(p; k) stand for a single-hop network that has p stations and k communication channels. The problems of sorting and selection have been studied on RN(p; k). For these problems it is assumed that there are n/p elements to start with at each station. At the end of sorting, the least n/p elements should be in the first station, the next smallest n/p elements should be in the second station, and so on. The best known prior algorithm for sorting takes 4n/k +o(n/k) broadcast rounds on a RN(p; k). In this paper we present a randomized algorithm that takes only 3n/k +o(n/k) broadcast rounds with high probability. For the selection problem, it is known that the maximum or minimum element can be found in O(log n) rounds on a RN(n; 1), provided broadcast conflicts can be resolved in O(1) time. The problem of general selection has not been addressed. In this paper we present a randomized selection algorithm that takes O(p/k) rounds on a RN(p; k) with high probability. An important message routing problem that is considered in the literature is one where there are n/p packets originating from each station and there are n/p packets destined for each station. The best known routing algorithms take nearly 2n/k times slots. An important open question has been if there exist algorithms that take only close to n/k time slots. Note that a trivial lower bound for routing is n/k. The existence of such algorithms will be highly relevant especially in emergencies and time critical situations. In this paper we answer this question by presenting a randomized algorithm that takes nearly n/k time slots with high probability.

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>

Clos networks provide theoretically optimal solution to build high-radix switches. Dynamically reconfiguring a three-stage Clos network is more difficult in asynchronous circuits than in synchronous circuits. This study proposes a novel asynchronous dispatching (AD) algorithm for general three-stage Clos networks. It is compared with the classic synchronous concurrent round-robin dispatching (CRRD) algorithm in unbuffered Clos networks. The AD algorithm avoids the contention in central modules using a state feedback scheme and outperforms the throughput of CRRD in behavioural simulations. Two asynchronous Clos networks using the AD algorithm are implemented and compared with a synchronous Clos network using the CRRD algorithm. The asynchronous Clos scheduler is smaller than its synchronous counterpart. Synchronous Clos networks achieve higher throughput than asynchronous Clos networks because asynchronous Clos networks cannot hide the arbitration latency and their data paths are slow. The asynchronous Clos scheduler consumes significantly lower power than the synchronous scheduler and the asynchronous Clos network using bundled-data data switches shows the best power efficiency in all implementations.

A fast and efficient distributed sub-optimal routing algorithm using hierarchical aggregation/disaggregation (HAD) scheme is proposed for high speed Internet based on IPv6. The hierarchical structure eliminates the dominant scaling limit of the routing algorithm. It allows the number of subnetworks that must be known to any single router to be bounded. Our algorithm is different from existing HAD algorithms in high level network routing algorithm and composition algorithm. Unlike the previous algorithms, the origin and destination can be any node in the flat network. We compared our algorithm with traditional optimal routing algorithm by gradient projection (TOR-GP) method using the system delay as an objective function. The results show that our algorithm converges much faster than traditional algorithm, and provides a very good approximation to the traditional algorithm. It is safe to say that the solution should have positive effects to the rapid development of the information super-highway.

Wireless sensor networks (WSNs) are being used in a wide variety of critical applications such as military and health‐care applications. Such networks, which are composed of sensor nodes with limited memory capacity, limited processing capabilities, and most importantly limited energy supply, require routing protocols that take into consideration these constraints. The aim of this paper is to provide an efficient power aware routing algorithm for WSNs that guarantees QOS and at the same time minimizes energy consumption by calculating the remaining battery capacity of nodes and taking advantage of the battery recovery process. We present an online‐battery aware geographic routing algorithm. To show the effectiveness of our approach, we simulated our algorithm in ns2 and compared it with greedy perimeter stateless routing for wireless networks and battery‐aware routing for streaming data transmissions in WSNs. Copyright © 2009 John Wiley &amp; Sons, Ltd.

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.

Energy efficiency is a key concern and challenging research issue during the design of routing algorithms for wireless sensor networks (WSNs). In order to effectively improve the energy utilization of each sensor node and network performance, mobility technology has been widely concerned. Since the implement of mobile sink node is relatively easier than normal sensor nodes, sink mobility technology has attracted much research interest in recent years. In this paper, we propose a mobile-sink routing algorithm based on energy and distance for WSNs. Trajectories of mobile sink nodes is predictable to improve energy efficiency of sensor networks. We first lay emphasis on the study of the selection of mobile sink node number and the selection of park positions, as well as their impact on energy consumption and network lifetime. Simulation results show that both the mobile sink nodes number and park positions have great influence on network performance, and our algorithm outperforms random movement and LEACH algorithm in terms of performance like energy consumption.

Probabilistic Look-ahead Contingency Analysis Integration with Commercial Tool and Practical Data

The authors deal with optical implementation of crossbar switches and a Clos network, using reversible nonlinear interface (RNI) devices. The proposed building block for these implementations is a two-by-two optical switch box capable of performing four basic switching actions. The routing algorithms for the Clos network are discussed. Some applications for these networks are suggested. >

Wireless Sensor Networks (WSNs) are usually comprised of a large number of sensor nodes which have limited power resources and require energy efficient routing algorithms. We have presented an Adaptive Transmission Power - Geographical and Energy Aware Routing (ATP-GEAR) algorithm in this paper, which routes the packet towards the destination by calculating the cost of the neighbors of a node in terms of their location and current battery level and transmitting the packet to the lowest costing node with the minimum required transmission power. We analyze the performance of our algorithm based on total power consumption and end-to-end delay from source to destination. Simulation results show that ATP-GEAR yields almost 25% less power consumption and 17% less end-to-end delay when compared with traditional Cluster Based Routing (CBR).

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.