On modelling of an adaptive routing algorithm for massively parallel processing systems

A theory for the design of deadlock-free adaptive routing algorithms for wormhole networks, proposed by the author (1991, 1993), supplies sufficient conditions for an adaptive routing algorithm to be deadlock-free, even when there are cyclic dependencies between channels. Also, two design methodologies were proposed. Multicast communication refers to the delivery of the same message from one source node to an arbitrary number of destination nodes. A tree-like routing scheme is not suitable for hardware-supported multicast in wormhole networks because it produces many headers for each message, drastically increasing the probability of a message being blocked. A path-based multicast routing model was proposed by Lin and Ni (1991) for multicomputers with 2D-mesh and hypercube topologies. In this model, messages are not replicated at intermediate nodes. This paper develops the theoretical background for the design of deadlock-free adaptive multicast routing algorithms. This theory is valid for wormhole networks using the path-based routing model. It is also valid when messages with a single destination and multiple destinations are mixed together. The new channel dependencies produced by messages with several destinations are studied. Also, two theorems are proposed, developing conditions to verify that an adaptive multicast routing algorithm is deadlock-free, even when there are cyclic dependencies between channels. As an example, the multicast routing algorithms of Lin and Ni are extended, so that they can take advantage of the alternative paths offered by the network.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

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>

Adaptive routing is widely regarded as a promising approach to improving interconnection network performance. Many designers of adaptive routing algorithms have used synthetic communication patterns, such as uniform and transpose traffic, to compare the performance of various adaptive routing algorithms with each other and with oblivious routing. These comparisons have shown that the average message latency is usually lower with adaptive routing. On the other hand, when a parallel program is executed on a multiprocessor the goal is to reduce the total execution time. We explain why improving the average message latency of a routing algorithm does not necessarily lead to a lower execution time for real applications. We support this observation by reporting simulation results for both adaptive and oblivious routing using communication derived from real applications. Specifically, we report the performance of various routing algorithms for directed acyclic graphs (DAGs) derived from the Cholesky factorization of sparse matrices. Our results show that there is little correlation between average message latency and the total execution time of a parallel program. Hence, average message latency does not seem to be a useful measure of the performance of a routing algorithm. This strongly suggests that current comparisons of routing algorithms do not provide a reliable indication of the performance improvements to be realized by executing programs on a multiprocessor with such a routing algorithm. We interpret these results and suggest several alternatives for further research.

Due to Low-Rate Wireless Personal Area Networks(LR-WPANs) is popularly used in Internet of Things (IOT) in recent years, Chiu and Wang proposed a linked list routing algorithm with wormhole mechanism, which includes the linked list network construction mechanism, the wormhole mechanism and the MODBUS extension instructions for data collection. There are still a lot of non-adaptive problems in that algorithm, such that network initialization problem, continuous nodes broken problem and node outliers problem. Those problems could make the whole network stay in unstable state when the special conditions bring out. In this paper, we proposed an adaptive linked-list routing algorithm with wormhole mechanism. By proposed the Lock-address mechanism fundamentally, we can make the stable chain scission, reset sequentially and cutting timer determination mechanism for broken nodes. In simulation, the performance of network initialization of adaptive linked-list routing algorithm with wormhole mechanism and flooding is compared and simulated by NS3 in this paper. The simulations results reveal that the initialization of adaptive linked-list routing algorithm with wormhole mechanism is more efficient than flooding when nodes are 5 meters apart and a matrix model of nodes number from 7*7 to 15*15.

Many adaptive routing algorithms for wormhole-routed k-ary n-cubes have been proposed to overcome the performance limitations of deterministic routing. However, before such routing schemes can be successfully incorporated in future practical multicomputers, it is necessary to develop a clear understanding of the factors that affect their potential performance. Boppanna and Chalasani have recently proposed a routing algorithm (referred to as hop-based routing) that achieves full adaptivity in wormhole-routed k-ary n-cubes using a hop-based scheme borrowed from traditional store-and forward networks. A new analytical model is prepared to compute message latency in k-ary n-cubes with hop-based routing. Results from simulation experiments reveal that the proposed model exhibits a good degree of accuracy in predicting message latency.

Wireless sensor networks area collection of a large number of unattended sensor nodes. The sensor nodes are dynamically deployed in the region. In wireless sensor networks, the unlicensed sensor nodes use their temporarily available vacant licensed channels or spectrum band in a telecommunication network. The many open challenges with issues such as adaptive in self-organisation, fault-tolerance and network scalability with cooperative spectrum sensing and sharing are identifying new challenges in wireless sensor networks. In this paper, we proposed the bio-inspired adaptive routing algorithm for cognitive radio wireless sensor networks. The utilisation of the foraging approach of ANTs and BEEs for making the decision of using the available spectrum sensing and sharing of channels over multi-hops communication, provides the method to utilise idle channel and decrease the delay for communication in wireless sensor network. In this paper, we design the algorithm to solve the issue of wireless sensor network and performance of classical routing protocol LEACH and cognitive radio sensor networks (CRSN) evaluates the parameters which proof the self-organisation routing algorithm.

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.

Aiming at the problems of high dynamic topology and limited on-board resources in Low Earth Orbit (LEO) satellite networks leading to poor performance of traditional routing algorithms, this paper combines the centralized control idea of Software-Defined Networking (SDN) with the collective learning ability of the Particle Swarm Optimization (PSO) algorithm to propose an adaptive potential field routing algorithm based on PSO. This algorithm models the network as a dynamic potential field, defines potential energy based on the cumulative congestion degree to guide data packet transmission; adaptively learns and optimizes link cost weights through the PSO mechanism, achieving dynamic evolution of the path evaluation criterion; and adopts a probability-based multi-path forwarding mechanism to achieve load balancing. Simulation results show that compared to traditional algorithms such as Dijkstra and ACO (Ant Colony Optimization), this algorithm significantly improves performance in terms of average end-to-end delay, network throughput, and load balancing, especially suitable for dynamic traffic scenarios.

Delay Tolerant Networks are characterized by (i) intermittent connectivity that is there is no reliable end-to-end path,(ii) long delay in delivery of packets from source to destination and (iii) the nodes are sparse and mobile. Traditional protocols do not work for such an environment. DTN is deployed in interplanetary networks, wild life tracking, disaster management, underwater networks. Routing in DTN is by store-carry-forward technique, where the source or the intermediate node stores the packet until it meets the node for forwarding. The major constraints or challenges are energy level constraint, mobility patterns, selection of intermediate nodes, effective usage of the limited network resources like buffer space etc. This paper provides the study of various DTN routing algorithms and their categories are summarized.

Randomized self-routing algorithms for Clos networks

To improve the performance of route overhead and packet dropped rate of routing algorithms in mobile ad hoc networks, a location-based grid routing (LBGR) algorithm is presented. By node position information, the LBGR algorithm employs a grid-constructed trajectory instead of node ID in forwarding packets. Based on the position relationship of nodes and downstream grids, each intermediate node infers the next hop to relay packets. Therefore, it can adapt to frequent and unpredictable topology changes in the presence of high mobility and greatly enhance the robustness of route maintenance. Simulation results show that the proposed algorithm can reduce route overhead, packet dropped rate and the average number of hops per path

Several proposed routing algorithms for store and forward communication networks, including one currently in operation in the ARPANET route messages along shortest paths computed by using some set of link lengths. When these lengths depend on current traffic conditions as they must in an adaptive algorithm, dynamic behavior questions such as stability, convergence, and speed of convergence are of interest. This paper is the first attempt to analyze systematically these issues. It is shown that minimum queuing delay path algorithms tend to exhibit violent oscillatory behavior in the absence of a damping mechanism. The oscillations can be damped by means of several types of schemes two of which are analyzed in this paper. In the first scheme a constant bias is added to the queuing delay thereby providing a preference towards paths with a small number of links. In the second scheme the effects of several past routings are averaged as for example when the link lengths are computed and communicated asynchronously throughout the network.

In order to optimize the delay of data transmission and the routing efficiency of routing search algorithm, an adaptive routing search algorithm for SRIO network based on chaotic ant colony algorithm is proposed. This paper analyzes the principle of SRIO network transfer transaction, and selects routing information by exchanging properties of SRIO network packets. Using chaotic ant colony algorithm, the LEACH protocol of SRIO network is established to search the best relay node adaptively, and the SRIO network routing adaptive search algorithm is designed. Experimental results show that the proposed algorithm can effectively reduce the delay of data transmission and optimize the routing efficiency.

Ad hoc networks can be very mobile, where mobile nodes (MNs) are moving frequently relative to one another. The faster the MNs are moving, the more the routing information is required to keep each MNs informed of the route information to other MNs. This paper proposes a hybrid routing algorithm, whose behavior is modified dynamically based on MN's mobility in the network. This would allow using proactive algorithms when a network has low mobility, and allow using reactive algorithms when a network becomes very mobile. In this paper, destination sequenced distance vector (DSDV) is used as a proactive routing algorithm and ad hoc on-demand vector (AODV) is used as a reactive algorithm.