Shortest Path Routing

IntroductionA hypercube is a distributed parallel systemconsisting of 2nidentical processors, each providedwith its own sizable memory and interconnectedwith n neighbors. It has a homogeneoussymmetric structure and has necessarilyrich connectivity. It also has useful topologyin which many other topologies, such asmeshes, rings, trees can be embedded (Saadand Schultz, 1988, 1989).Hypercube structure started to be investigatedin the 1970's and provided a good

Recently, cooperative routing in wireless networks has gained much interest due to its ability to exploit the broadcast nature of the wireless medium in designing power-efficient routing algorithms. Most of the existing cooperation-based routing algorithms are implemented by finding a shortest-path route first. As such, these routing algorithms do not fully exploit the merits of cooperative communications at the physical layer. In this paper, we propose a cooperation-based routing algorithm, namely, minimum power cooperative routing (MPCR) algorithm, which makes full use of the cooperative communications while constructing the minimum-power route. The MPCR algorithm constructs the minimum-power route as a cascade of the minimum-power single-relay building blocks from the source to the destination. Hence, any distributed shortest-path algorithm can be utilized to find the optimal route with polynomial complexity, while guaranteeing certain throughput. We show that the MPCR algorithm can achieve power saving of 57.36% compared to the conventional shortest-path routing algorithms. Furthermore, the MPCR algorithm can achieve power saving of 37.64% compared to the existing cooperative routing algorithms, in which the selected routes are constructed based on the noncooperative routes.

This paper compares two path selection strategies for Optical Burst Switching networks: a) the path from source to destination is chosen randomly from the set of the k shortest paths; b) the path selection is based on a probabilistic model for the link demands. In the second strategy, the set of shortest paths from source to destination is ranked according to the probability of their overall link demands. The path selection schemes are evaluated for a specific scenario of Grid over OBS networks. Our results show that, in general, the probabilistic model outperforms the random k shortest path routing scheme, this improvement is relevant for small job sizes.

A new dynamic channel allocation scheme (DCAS) has been proposed for mobile satellite systems with the aim of improving the utilization of the network resources by reducing the handoff call dropping probability (HODP) while guaranteeing a certain quality of service for the new call blocking probability (NCBP). The arriving calls are given channels based on their priority. The handoff calls

To effectively manage the material handling in Flexible Manufacturing Systems (FMS), where a large amount of data is required in the dynamic decision-making, integrated control is needed to consider the overall production schedule. The focus of this research is on the development of an integrated Automated Guided Vehicle System (AGVS) control model that includes essential features like dynamic vehicle path determination and conflict-free routing. An object-oriented implementation of the AGVS model is proposed that forms the basis of systems integration with a production planning module such as MRI? Static and dynamic informational and functional models of the AGVS are developed. The system incorporates: (i) conflict-free shortest path routing procedures, and (ii) vehicle assignment rules or scheduling strategies. A prototype version of each of these has been developed for demonstrative purposes. This object-oriented. modelling methodology provides the capability of rapid development and change. The approach has been demonstrated for a real manufactured product through simulation studies which confirm the superior performance of anticipatory AGVS control rules, even in a production orderdriven environment. 0 1997 Elsevier Science Ltd. Production order-driven AGV control model: A4 Shah et al. 47 Davis, W J 'Real-time optimization in the automated research facility', in J White and I W Pence (eds), Progress in Material Handling I,ogistics ( 1989) 48 Production order-dtiven AGV control model: M Shah et al. 7 Jones, A and Mclean, C 'A proposed hierarchical control model for automated manufacturing systems', Journal of Manufacturing Systems, Vol 5 No 1 (1986) pp 15-25 8 Tirpak, T M, Deligiannis, S J and Davis, W J 'Real-time scheduling in flexible manufacturing', Manufacturing Review, Vol5 No 3 (1992) pp 193-212 9 Simpson, J A, Hocken, R J and Albus, J S 'The automated manufacturing research facility of the national bureau of stan-

Bandwidth brokers as proposed in the diffserv framework build on the process of setting up Service Level Agreements (SLA). This is a very static procedure, usually performed manually and based only on a simple description of the SLA. However, diffserv is suited to handle a more dynamic environment and to provide more than connectivity with its service classes. Our proposal enhances bandwidth brokers by including more significant information in SLAs such as the flow's destination network and pricing. In addition, we present a new per-hop behavior that supports flexible allocation of code points which is important to our approach. The system is targeted at large ISPs with good inter-connectivity. We implemented it on top of a flow-based simulation engine. The evaluation is based on parts of the current AS topology and characteristics of aggregated traffic. The results show an improvement of network utilization by up to 40% over a traditional, shortest-path routed inter-domain network for a wide range of network and traffic parameters.

Designing an efficient routing algorithm for LEO satellite constellations is crucial for optimizing IP over Satellite (IPoS) network resources. Since there could be many shortest paths between two satellites, an efficient routing algorithm should provide better utilization of these paths. For this purpose, we propose a Priority-based Adaptive Routing (PAR) technique, which distributedly sets the shortest path through a destination. In this technique, a direction decision is made at each hop by a priority mechanism, depending on the past utilization and buffering information about the links. We further make some enhancements on PAR, and propose ePAR algorithm that also accounts for the contentions between packets with different source-destination pairs. We explore the performances of PAR and ePAR algorithms based on an extensive set of simulations, and compared their performances with static and adaptive routing techniques as a reference. Obtained results show that while the proposed PAR algorithm is promising for use in LEO satellite networks, ePAR algorithm may be more suitable for MEO satellite networks.

The purpose of routing protocols in a computer network is to maximize network throughput. Popular shortest-path routing protocols have the disadvantage of causing bottlenecks due to their single-path routing. That is, the shortest path between a source and a destination may become highly congested even when many other paths have low utilization. In this paper, we propose a routing scheme

One of the most important methods for evaluating the characteristics of ad hoc networking protocols is through the use of simulation. Simulation provides researchers with a number of significant benefits, including repeatable scenarios, isolation of parameters, and exploration of a variety of metrics. The topology and movement of the nodes in the simulation are key factors in the performance of the network protocol under study. Once the nodes have been initially distributed, the mobility model dictates the movement of the nodes within the network. Because the mobility of the nodes directly impacts the performance of the protocols, simulation results obtained with unrealistic movement models may not correctly reflect the true performance of the protocols. The majority of existing mobility models for ad hoc networks do not provide realistic movement scenarios; they are limited to random walk models without any obstacles. In this paper, we propose to create more realistic movement models through the incorporation of obstacles. These obstacles are utilized to both restrict node movement as well as wireless transmissions. In addition to the inclusion of obstacles, we construct movement paths using the Voronoi diagram of obstacle vertices. Nodes can then be randomly distributed across the paths, and can use shortest path route computations to destinations at randomly chosen obstacles. Simulation results show that the use of obstacles and pathways has a significant impact on the performance of ad hoc network protocols.

We propose an approach to determine the shortest path between the source and the destination nodes in a faulty or a non-faulty hypercube. The number of faulty nodes and links may be rather large and if any path between the nodes exists, the developed algorithm determines it. To construct this algorithm, some properties of the cube algebra are considered and some transformations based on this algebra are developed. Ó

To effectively manage the material handling in Flexible Manufacturing Systems (FMS), where a large amount of data is required in the dynamic decision-making, integrated control is needed to consider the overall production schedule. The focus of this research is on the development of an integrated Automated Guided Vehicle System (AGVS) control model that includes essential features like dynamic vehicle path determination and conflict-free routing. An object-oriented implementation of the AGVS model is proposed that forms the basis of systems integration with a production planning module such as MRI? Static and dynamic informational and functional models of the AGVS are developed. The system incorporates: (i) conflict-free shortest path routing procedures, and (ii) vehicle assignment rules or scheduling strategies. A prototype version of each of these has been developed for demonstrative purposes. This object-oriented. modelling methodology provides the capability of rapid development and change. The approach has been demonstrated for a real manufactured product through simulation studies which confirm the superior performance of anticipatory AGVS control rules, even in a production orderdriven environment. 0 1997 Elsevier Science Ltd. Production order-driven AGV control model: A4 Shah et al. 47 Davis, W J 'Real-time optimization in the automated research facility', in J White and I W Pence (eds), Progress in Material Handling I,ogistics ( 1989) 48 Production order-dtiven AGV control model: M Shah et al. 7 Jones, A and Mclean, C 'A proposed hierarchical control model for automated manufacturing systems', Journal of Manufacturing Systems, Vol 5 No 1 (1986) pp 15-25 8 Tirpak, T M, Deligiannis, S J and Davis, W J 'Real-time scheduling in flexible manufacturing', Manufacturing Review, Vol5 No 3 (1992) pp 193-212 9 Simpson, J A, Hocken, R J and Albus, J S 'The automated manufacturing research facility of the national bureau of stan-

Applications such as VoIP need to provide anonymity to clients while maintaining low latency to satisfy quality of service (QoS) requirements. Existing solutions for providing anonymity such as mix networks are not well suited to applications like VoIP, SSH, and gaming which require low communication latency. This paper investigates the problem of on-demand construction of QoS sensitive routes on anonymizing networks using the VoIP application. We first describe triangulation based timing analysis attacks on shortest path route set up protocols. We show that even when a small fraction (∼1%) of the network is malicious, the adversary can infer the source (caller) with reasonably high probability. Second, we describe random walk based route set up protocols that significantly improve anonymity while satisfying latencybased QoS guarantees. We describe a prototype implementation of our proposal and show that our protocols can significantly reduce the probability of inferring the caller. We present a detailed experimental evaluation to demonstrate our attacks and quantify the performance and scalability of our guards.

One of the promising lightwave network architectures is the multihop lightwave networks based on wavelength division multiplexing (WDM). In this architecture, separate channels created by assigning different wavelengths between node pairs define the logical connectivity. This logical topology is independent of the underlying physical topology and can be adaptively changed according to the changing traffic patterns and connectivity requirements. One of the possible objectives for designing this logical topology is minimizing the maximum utilization on any link by choosing the logical connectivity and finding the optimum routing. This paper describes an algorithm based on simulated annealing for solving the joint logical topology design and routing problem. Different algorithms were implemented for the cases with bifurcated and shortest path routing. Computational experiments showed that the simulated annealing solutions are as good as or better than the solutions found in previous studies.

A number of routing algorithms based on the ant-colony metaphor have been proposed for communication networks. However, there has been little work on the performance analysis of ant-routing algorithms. In this paper, we compare the performance of AntNet, an ant-routing algorithm, with Dijkstra's shortest path algorithm. Our simulations show that the performance of AntNet is comparable to Dijkstra's shortest path algorithm. Moreover, under varying traffic loads, AntNet adapts to the changing traffic and performs better than shortest path routing. (S.S. Dhillon).

Recently, the merits of cooperative communication in the physical layer have been explored. However, the impact of cooperative communication on the design of the higher layers has not been well-understood yet. Cooperative routing in wireless networks has gained much interest due to its ability to exploit the broadcast nature of the wireless medium in designing power efficient routing algorithms. Most of the existing cooperation based routing algorithms are implemented by finding a shortest path route first and then improving the route using cooperative communication. As such, these routing algorithms do not fully exploit the merits of cooperative communications, since the optimal cooperative route might not be similar to the shortest path route. In this paper, we propose a cooperation-based routing algorithm, namely, the minimum power cooperative routing (MPCR) algorithm, which makes full use of the cooperative communications while constructing the minimum-power route. The MPCR algorithm constructs the minimum-power route, which guarantees certain throughput, as a cascade of the minimum-power single-relay building blocks from the source to the destination. Thus, any distributed shortest path algorithm can be utilized to find the optimal cooperative route with polynomial complexity. Using analysis, we show that the MPCR algorithm can achieve power saving of 65.61% in regular linear networks and 29.8% in regular grid networks compared to the existing cooperation-based routing algorithms, where the cooperative routes are constructed based on the shortest-path routes. From simulation results, MPCR algorithm can have 37.64% power saving in random networks compared to those cooperation-based routing algorithms.

The recent reduction in telecommunications spending has increased the importance of network planning to improve the return on investment on the existing network infrastructures. Therefore, tools that help in maximizing the bandwidth efficiency of the network at a minimum cost are essential. Previous work in this area focused on increasing bandwidth efficiency and reliability. In this work, in addition to increasing the bandwidth efficiency, we address the complexity of network management and operations. This issue is explicitly addressed by our novel framework, a simple polynomial time algorithm (SimPol) that achieves optimum network performance (in terms of congestion or bandwidth consumption) using only a small number of paths. The problem formulation is based on splittable multicommodity flows. Using SimPol we show that the total number of paths is at most k + m, where k and m are the numbers of demands and edges in the network, respectively. We extend the basic framework into an integer programming formulation to address the tradeoff between network congestion and the total number of paths. We also use SimPol to address the problem of implementing path/link policies such as bandwidth-limited paths. The performance of SimPol is evaluated through extensive simulations. We find that for large number of demands the LPbased framework provides a near-optimal solution of almost one path per demand. Using the integer programming approach, we can get exactly one path while losing about 10% to 50% in congestion depending on the number of demands. This congestion is, however, far better than the traditional shortest path routing. The framework is general and can be used in capacity planning for transport networks such as MPLS and ATM.

Wireless sensor networks represent a key technology enabler for enhanced health care and assisted living systems. Recent standardization efforts to ensure compatibility among sensor network systems sold by different vendors have produced the IEEE 802.15.4 standard, which specifies the MAC and physical layer behavior. This standard has certain drawbacks: it supports only single-hop communication; it does not mitigate the hidden terminal problem; and it does not coordinate node sleeping patterns. The IEEE 802.15.4 standard design philosophy assumes that higher layer mechanisms will take care of any added functionality. Building on IEEE 802.15.4, this paper proposes TImezone COordinated Sleep Scheduling (TICOSS), a mechanism inspired by MERLIN [2] that provides multi-hop support over 802.15.4 through the division of the network into timezones.

Traffic engineering involves adapting the routing of traffic to the network conditions, with the joint goals of good user performance and efficient use of network resources. In this paper, we describe an approach to intradomain traffic engineering that works within the existing deployed base of Interior Gateway Protocols (IGPs), such as Open Shortest Path First (OSPF) and Intermediate System-Intermediate System (IS-IS). We explain how to adapt the configuration of link weights, based on a network-wide view of the traffic and topology within a domain. In addition, we summarize the results of several studies of techniques for optimizing OSPF/IS-IS weights to the prevailing traffic. The paper argues that traditional shortest-path routing protocols are surprisingly effective for engineering the flow of traffic in large IP networks. §

Systems on Chip (SoCs) require efficient inter-module interconnection providing for the required communications at a low cost. We analyze the generic cost in area and power of Networks on Chip (NoCs) and alternative interconnect architectures: a shared bus, a segmented bus and a point-to-point interconnect. For each architecture we derive analytical expressions for area, power dissipation and operating frequency as well as asymptotic limits of these functions. The analysis quantifies the intuitive NoC scalability advantages.

Ad Hoc Networks are multi -hop wireless networks with dynamically changing network connectivity owing to mobility. The protocol suite includes several routing protocols specifically designed for ad-hoc routing. The conventional routing protocols such as shortest-path routing algorithms are not particularly well suited for operation in ad-hoc networking environment. The most widely used ad hoc routing protocols are Ad-hoc On-Demand Distance Vector Routing (AODV), Destination Sequenced Distance Vector (DSDV), Dynamic Source Routing (DSR) and Temporally -Ordered Routing Algorithm (TORA). In this paper, the three random based mobility models such as Random waypoint, Random walk and Random Directions were implemented. The two different parameter constraints like packet-delivery fraction and End-toend packet delivery delay are compared with respect to mobility speed, Traffic and Network size. The simulation results shows that the AODV protocols in Random Waypoint mobility model performs better than DSDV, TORA and DSR in Random walk and random Direction mobility model. . Based on the observations, it is to suggest that AODV routing protocol can be used under high mobility since it outperforms DSDV, TORA and DSR protocols.

Mapping the Internet generally consists in sampling the network from a limited set of sources by using traceroute-like probes. This methodology has been argued to introduce uncontrolled sampling biases that might produce statistical properties of the sampled graph which sharply differ from the original ones. Here we explore these biases and provide a statistical analysis of their origin. We derive a mean-field analytical approximation for the probability of edge and vertex detection that allows us to relate the global topological properties of the underlying network with the statistical accuracy of the sampled graph. In particular we show that shortest path routed sampling allows a clear characterization of underlying graphs with scale-free topology. We complement the analytical discussion with a throughout numerical investigation of simulated mapping strategies in different network models.

In this work, we propose the use of an Ant Colony Optimization (ACO) algorithm to mitigate packet loss in an optical packet switching network that carries selfsimilar traffic, which is known to have a great impact in the buffer performance in terms of loss probability as exemplified in this work. By adaptively routing the packets and balancing the network load, we demonstrate by some simulations the effectiveness of this approach when compared with a shortest-path routing scheme, achieving a performance that is comparable to the Poisson traffic scenario in some cases. The proposed algorithm can be used as a viable alternative to traffic shaping techniques.

Tree-based Routing (TRE) revisits Tree-based Routing Architecture for Irregular Networks (TRAIN)-a forwarding scheme based on a spanning tree that was extended to use some shortcut links. We propose its adaptation to Ethernet, using a new type of hierarchical Ethernet addresses and a procedure to assign them to bridges. We show that compared to RSTP, TRE offers improved throughput. The impact of transient loops in TRE is lower compared to the application of the classical shortest path routing protocols to Ethernet. Finally, TRE is self-configuring and its forwarding process is simpler and more efficient than in standard Ethernet and shortest path routing proposals.

Mobile Ad-hoc networks are self-reliant system of mobile phones associated by mobile ad-hoc links. All hops in the framework collaborate so as to effectively route packets in multi-hop networks. Because of the eccentric versatility of hops, the system topology may change continually. Ad-hoc systems are fabricated and utilized as convenient in incredibly progressive situations, not really with the assistance of an earlier existing structure. Due to the none-centralized system routing is the essential issue for MANET. Different routing protocols have been developed in recent decade like AODV, DYMO, DSDV and DSR etc. This research study shows the simulation analysis of reactive, proactive and hybrid routing protocols. The performance matrices were analyzed packet ratio delivery (PDR), throughput, endtoend delay and Normalized routing load (NRL). NS-2.35 network simulation has been used for overall study experiments with respect to discrete number of hops and different pause time. From the experiment it is come to terms on that DSDV and DSR are performs well in all performance matrices.

In a distributed sensor network, large number of sensors deployed which communicate among themselves to selforganize a wireless ad hoc network. We propose an energyefficient level-based hierarchical system. We compromise between the energy consumption and shortest path route by utilizing number of neighbors (NBR) of a sensor and its level in the hierarchical clustering. In addition, we design a Secure Routing Protocol for Sensor Networks (SRPSN) to safeguard the data packet passing on the sensor networks under different types of attacks. We build the secure route from the source node to sink node. The sink node is guaranteed to receive correct information using our SRPSN. We also propose a group key management scheme, which contains group communication policies, group membership requirements and an algorithm for generating a distributed group key for secure communication. important concepts for group key management; they are 1) Key trees 2) Diffie -Hellman [10] key exchange protocol. Key tree is used for updating group keys, and Diffie -Hellman protocol is used for computing group key. The rest of the paper is organized as follows. A hierarchical architecture is given in Section 2. In Section 3, we present a secure routing protocol. In Section 4, we develop a key management protocol. We conclude the paper in Section 5.

We present the boomerang protocol to efficiently retain information at a particular geographic location in a sparse network of highly mobile nodes without using infrastructure networks. To retain information around certain physical location, each mobile device passing that location will carry the information for a short while. This approach can become challenging for remote locations around which only few nodes pass by. To address this challenge, the boomerang protocol, similar to delay-tolerant communication, first allows a mobile node to carry packets away from their location of origin and periodically returns them to the anchor location. A unique feature of this protocol is that it records the geographical trajectory while moving away from the origin and exploits the recorded trajectory to optimize the return path.

In the last decade, due to emerging real-time and multimedia applications, there has been much interest for developing mechanisms to take into account the quality of service required by these applications. One of these mechanisms consists to integrate simultaneously many criteria of quality of service (QoS) in routing decision. Efficient routing of information packets in dynamically changing communication network requires that as the load levels, traffic patterns and topology of the network change, the routing policy also adapts. We propose in this paper an approach used an adaptive algorithm for packet routing using reinforcement learning called AV-BW Delay Q-Routing. This approach is based on earlier developed K-Optimal path Q-Routing Algorithm (KOQRA) which optimizes simultaneously two additive QoS criteria: cumulative cost path and end-to-end delay. The approach developed here adds a third criterion to KOQRA regarding residual bandwidth. This proposed technique uses an inductive approach based on trial/error paradigm combined with swarm adaptive approaches. The whole algorithm uses a model combining both a stochastic planned pre-navigation for the exploration phase and a deterministic approach for the backward phase. Numerical results obtained with OPNET simulator for different levels of traffic's load show that AV-BW Delay Q-Routing improves clearly performances of our earlier KOQRA

Shortest path routing is the type of routing widely used in computer networks nowadays. Even though shortest path routing algorithms are well established, other alternative methods may have their own advantages. One such alternative is to use a

Recently, cooperative routing in wireless networks has gained much interest due to its ability to exploit the broadcast nature of the wireless medium in designing powerefficient routing algorithms. Most of the existing cooperationbased routing algorithms are implemented by finding a shortestpath route first. As such, these routing algorithms do not fully exploit the merits of cooperative communications at the physical layer. In this paper, we propose a cooperation-based routing algorithm, namely, Minimum Power Cooperative Routing (MPCR) algorithm, which makes full use of the cooperative communications while constructing the minimum-power route. The MPCR algorithm constructs the minimum-power route as a cascade of the minimum-power single-relay building blocks from the source to the destination. Hence, any distributed shortestpath algorithm can be utilized to find the optimal route with polynomial complexity, while guaranteeing certain throughput. We show that the MPCR algorithm can achieve power saving of 57.36% compared to the conventional shortest-path routing algorithms. Furthermore, the MPCR algorithm can achieve power saving of 37.64% compared to the existing cooperative routing algorithms, in which the selected routes are constructed based on the noncooperative routes.

Designing an efficient routing algorithm for LEO satellite constellations is crucial for optimizing IP over Satellite (IPoS) network resources. Since there could be many shortest paths between two satellites, an efficient routing algorithm should provide better utilization of these paths. For this purpose, we propose a Priority-based Adaptive Routing (PAR) technique, which distributedly sets the shortest path through a destination. In this technique, a direction decision is made at each hop by a priority mechanism, depending on the past utilization and buffering information about the links. We further make some enhancements on PAR, and propose ePAR algorithm that also accounts for the contentions between packets with different source-destination pairs. We explore the performances of PAR and ePAR algorithms based on an extensive set of simulations, and compared their performances with static and adaptive routing techniques as a reference. Obtained results show that while the proposed PAR algorithm is promising for use in LEO satellite networks, ePAR algorithm may be more suitable for MEO satellite networks.

Recently, cooperative routing in wireless networks has gained much interest due to its ability to exploit the broadcast nature of the wireless medium in designing powerefficient routing algorithms. Most of the existing cooperationbased routing algorithms are implemented by finding a shortestpath route first. As such, these routing algorithms do not fully exploit the merits of cooperative communications at the physical layer. In this paper, we propose a cooperation-based routing algorithm, namely, Minimum Power Cooperative Routing (MPCR) algorithm, which makes full use of the cooperative communications while constructing the minimum-power route. The MPCR algorithm constructs the minimum-power route as a cascade of the minimum-power single-relay building blocks from the source to the destination. Hence, any distributed shortestpath algorithm can be utilized to find the optimal route with polynomial complexity, while guaranteeing certain throughput. We show that the MPCR algorithm can achieve power saving of 57.36% compared to the conventional shortest-path routing algorithms. Furthermore, the MPCR algorithm can achieve power saving of 37.64% compared to the existing cooperative routing algorithms, in which the selected routes are constructed based on the noncooperative routes.

We focus on data gathering problems in energy constrained networked sensor systems. The system operates in rounds where a subset of the sensors generate a certain number of data packets during each round. All the data packets need to be transferred to the base station. The goal is to maximize the system lifetime in terms of the number of rounds the system can operate. We show that the above problem reduces to a restricted flow problem with quota constraint, flow conservation requirement, and edge capacity constraint. We further develop a strongly polynomial time algorithm for this problem, which is guaranteed to find an optimal solution. We then study the performance of a distributed shortest path heuristic for the problem. This heuristic is based on self-stabilizing spanning tree construction and shortest path routing methods. In this heuristic, every node determines its sensing activities and data transfers based on locally available information. No global synchronization is needed. Although the heuristic cannot guarantee optimality, simulations show that the heuristic has good average case performance over randomly generated deployment of sensors. We also derive bounds for the worst case performance of the heuristic.

We propose a routing strategy in which connection requests with specific bandwidth demands can be assigned to one of several alternative paths connecting the source to the destination. The primary goal of this multiple-path approach is to compensate for the inaccuracy of the knowledge available to routing nodes, caused by the limited frequency of link state (LS) information exchanges. We introduce a collection of K-shortest path routing schemes and investigate their performance under a variety of traffic conditions and network configurations. We subsequently demonstrate that K-shortest path routing offers a lower blocking probability in all scenarios and more balanced link utilization than other routing methods discussed in the literature. With our approach, it is possible to reduce the frequency of link state exchanges, and the incurred bandwidth overhead, without compromising the overall performance of the network. Based on the proposed routing scheme, we investigate different link state dissemination algorithms, which are aimed at reducing the communication overhead by prioritizing the scope and differentiating the qualitative content of LS update messages.

Recently, cooperative routing in wireless networks has gained much interest due to its ability to exploit the broadcast nature of the wireless medium in designing power-efficient routing algorithms. Most of the existing cooperation-based routing algorithms are implemented by finding a shortest-path route first. As such, these routing algorithms do not fully exploit the merits of cooperative communications at the physical layer. In this paper, we propose a cooperation-based routing algorithm, namely, minimum power cooperative routing (MPCR) algorithm, which makes full use of the cooperative communications while constructing the minimum-power route. The MPCR algorithm constructs the minimum-power route as a cascade of the minimum-power single-relay building blocks from the source to the destination. Hence, any distributed shortest-path algorithm can be utilized to find the optimal route with polynomial complexity, while guaranteeing certain throughput. We show that the MPCR algorithm can achieve power saving of 57.36% compared to the conventional shortest-path routing algorithms. Furthermore, the MPCR algorithm can achieve power saving of 37.64% compared to the existing cooperative routing algorithms, in which the selected routes are constructed based on the noncooperative routes.

We consider the effect of network topology on the optimality of packet routing which is quantified by ␥ c , the rate of packet insertion beyond which congestion and queue growth occurs. We show that for any network, there exists an absolute upper bound, expressed in terms of vertex separators, for the scaling of ␥ c with network size N, irrespective of the static routing protocol used. We then derive an estimate to this upper bound for scale-free networks and introduce a static routing protocol, the "hub avoidance protocol," which, for large packet insertion rates, is superior to the shortest path routing protocol.

We consider the effects of network topology on the optimality of packet routing quantified by c, the rate of packet insertion beyond which congestion and queue growth occurs. The key result of this paper is to show that for any network, there exists an absolute upper bound, expressed in terms of vertex separators, for the scaling of c with network

We consider the effect of network topology on the optimality of packet routing which is quantified by ␥ c , the rate of packet insertion beyond which congestion and queue growth occurs. We show that for any network, there exists an absolute upper bound, expressed in terms of vertex separators, for the scaling of ␥ c with network size N, irrespective of the static routing protocol used. We then derive an estimate to this upper bound for scale-free networks and introduce a static routing protocol, the "hub avoidance protocol," which, for large packet insertion rates, is superior to the shortest path routing protocol.