Adaptive Routing Techniques Research Articles

Adaptive Routing Techniques for High Reliability in Multiprocessor Interconnection Networks

Massively parallel distributed memory multiprocessors (multicomputers) are increasingly being used in applications which demand high performance. These include real time applications in defence, robotics. Since massively parallel computers are also inherently less reliable due to the large number of components involved, it becomes essential to ensure reliable communication between nodes through fault tolerant routing algorithms. Conventionally, routing algorithms for multicomputers have concentrated on achieving minimality ie routing the message through a shortest path between the source and destination. In a safety-critical application, routing algorithms must be deadlock-free, be tolerant to node faults and link faults, and be capable of handling congestion resulting from non-uniform traffic. In this paper, we have made a survey of the adaptive routing techniques on direct interconnection networks.

Routing in frequency-hop packet radio networks with partial-band jamming

Research in adaptive, decentralized routing for frequency-hop packet radio networks with mobile partial-band jamming. A routing technique called least-resistance routing (LRR) is developed, and various versions of this routing method are examined. LRR uses a quantitative assessment of the interference environment experienced by a radio's receiver to determine a resistance value for that radio. Two components for the interference environment are considered: transmissions from other radios and partial-band jamming. The resistances for each of the radios in a particular path are combined to form the path resistance, and packets are forwarded on the path with the smallest resistance. Comparisons are made between different versions of LRR and between LRR and previously developed adaptive routing techniques. It is found that LRR is an effective way for dealing with mobile jamming in a frequency-hop packet radio network. Significant increases in throughput and end-to-end probability of success are obtained with LRR. >

Packet routing algorithms for integrated switching networks

Repeated studies have shown that a single switching technique, either circuit or packet switching, cannot optimally support a heterogeneous traffic mix composed of voice, video and data. Integrated networks support such heterogeneous traffic by combining circuit and packet switching in a single network. To manage the statistical variations of network traffic, we introduce a new, adaptive routing algorithm called hybrid, weighted routing . Simulations show that hybrid, weighted routing is preferable to other adaptive routing techniques for both packet switched networks and integrated networks.

File Allocation in a Distributed Computer Communication Network

An algorithm is presented to determine locations for the storage of copies of files in store-and-forward computer communications networks. The algorithm determines storage locations which minimize the sum of network file storage costs and message transmission costs. Networks that use adaptive routing techniques are the primary focus. Feasible file locations must satisfy network performance requirements for file availability and delay by message class. An effective method of evaluating delay constraints for networks using adaptive routing techniques is introduced. The algorithm uses the solution to a p-median problem to identify initial candidate file placements. Interaction between a set of file movement rules and a network simulator is employed to modify initial placements to fmd near-optimal locations which satisfy the network performance constraints.

On Routing and "Delta Routing": A Taxonomy and Performance Comparison of Techniques for Packet-Switched Networks

An inherent capability of packet-switched networks is the speed at which they can be reconfigured; various dynamic or adaptive routing techniques have been conceived to exploit this capability. In this study, existing techniques are described and an "ultra-dynamic" technique, delta routing, is invented. Several promising techniques are then selected for comparison with one another and with a network's ultimate carrying capacity. The goal is to shed light on the questions if and when one should use which kind of adaptive routing. First, a taxonomy of routing strategies is presented. In addition to delta routing, random, proportional, shortest path, and shortest path fixed-for-session duration are selected for comparison and their mechanisms described. The delay and efficiency performance of the five techniques are then compared with one another and with ideal behavior via simulations. These have been carried out concentrating on four very small networks, each with very different characteristics with the intention of gaining insight into the strengths and weaknesses of the various techniques. A ten-node network has also been simulated. The results favor delta routing which is most effective in highly interconnected network enviroments.

Adaptive Routing Techniques for Distributed Communications Systems

The concept of a netted or distributed communications system is significant because it offers a major advantage over conventional communications systems, i.e., a better chance of providing surviving lines of communication after an attack on the system. During and after an attack, however, an effective adaptive routing technique is necessary to adjust the routing tables of the message-switching control system to the changing situation. Previously investigated adaptive routing techniques are shown to be insufficient for the task, and a number of promising alternatives are formulated and investigated such as some stochastic techniques, which use information on messages passing through the network to adjust the tables, and some deterministic techniques, which use dynamic programming or graph-theoretic algorithms to recalculate changes in the tables from observed changes in the network. Each alternative has operational advantages, which make it good for certain types of communications systems, and certain disadvantages if applied to others. Regions of applicability and inapplicability, with respect to the above system parameters, are given for the various techniques. Recommended techniques are specified for two currently proposed applications of distributed communications systems. A number of research areas are pointed out in which further efforts in the analysis and simulation of adaptive routing techniques will have useful payoffs in the design of future distributed communications systems.

Adaptive routing techniques for distributed communications systems

Adaptive routing techniques for distributed communications systems