Showing papers on "Static routing published in 2008"

Efficient routing in intermittently connected mobile networks: the multiple-copy case

Abstract: Intermittently connected mobile networks are wireless networks where most of the time there does not exist a complete path from the source to the destination. There are many real networks that follow this model, for example, wildlife tracking sensor networks, military networks, vehicular ad hoc networks, etc. In this context, conventional routing schemes fail, because they try to establish complete end-to-end paths, before any data is sent. To deal with such networks researchers have suggested to use flooding-based routing schemes. While flooding-based schemes have a high probability of delivery, they waste a lot of energy and suffer from severe contention which can significantly degrade their performance. Furthermore, proposed efforts to reduce the overhead of flooding-based schemes have often been plagued by large delays. With this in mind, we introduce a new family of routing schemes that "spray" a few message copies into the network, and then route each copy independently towards the destination. We show that, if carefully designed, spray routing not only performs significantly fewer transmissions per message, but also has lower average delivery delays than existing schemes; furthermore, it is highly scalable and retains good performance under a large range of scenarios. Finally, we use our theoretical framework proposed in our 2004 paper to analyze the performance of spray routing. We also use this theory to show how to choose the number of copies to be sprayed and how to optimally distribute these copies to relays.

The vehicle routing problem : latest advances and new challenges

Abstract: Overviews and Surveys- Routing a Heterogeneous Fleet of Vehicles- A Decade of Capacitated Arc Routing- Inventory Routing- The Period Vehicle Routing Problem and its Extensions- The Split Delivery Vehicle Routing Problem: A Survey- Challenges and Advances in A Priori Routing- Metaheuristics for the Vehicle Routing Problem and Its Extensions: A Categorized Bibliography- Parallel Solution Methods for Vehicle Routing Problems- Recent Developments in Dynamic Vehicle Routing Systems- New Directions in Modeling and Algorithms- Online Vehicle Routing Problems: A Survey- Modeling and Solving the Capacitated Vehicle Routing Problem on Trees- Using a Genetic Algorithm to Solve the Generalized Orienteering Problem- An Integer Linear Programming Local Search for Capacitated Vehicle Routing Problems- Robust Branch-Cut-and-Price Algorithms for Vehicle Routing Problems- Recent Models and Algorithms for One-to-One Pickup and Delivery Problems- One-to-Many-to-One Single Vehicle Pickup and Delivery Problems- Challenges and Opportunities in Attended Home Delivery- Chvatal-Gomory Rank-1 Cuts Used in a Dantzig-Wolfe Decomposition of the Vehicle Routing Problem with Time Windows- Vehicle Routing Problems with Inter-Tour Resource Constraints- From Single-Objective to Multi-Objective Vehicle Routing Problems: Motivations, Case Studies, and Methods- Practical Applications- Vehicle Routing for Small Package Delivery and Pickup Services- Advances in Meter Reading: Heuristic Solution of the Close Enough Traveling Salesman Problem over a Street Network- Multiperiod Planning and Routing on a Rolling Horizon for Field Force Optimization Logistics- Health Care Logistics, Emergency Preparedness, and Disaster Relief: New Challenges for Routing Problems with a Focus on the Austrian Situation- Vehicle Routing Problems and Container Terminal Operations - An Update of Research

Contraction hierarchies: faster and simpler hierarchical routing in road networks

Abstract: We present a route planning technique solely based on the concept of node contraction. The nodes are first ordered by 'importance'. A hierarchy is then generated by iteratively contracting the least important node. Contracting a node υ means replacing shortest paths going through v by shortcuts. We obtain a hierarchical query algorithm using bidirectional shortest-path search. The forward search uses only edges leading to more important nodes and the backward search uses only edges coming from more important nodes. For fastest routes in road networks, the graph remains very sparse throughout the contraction process using rather simple heuristics for ordering the nodes. We have five times lower query times than the best previous hierarchical Dijkstra-based speedup techniques and a negative space overhead, i.e., the data structure for distance computation needs less space than the input graph. CHs can be combined with many other route planning techniques, leading to improved performance for many-to-many routing, transit-node routing, goal-directed routing or mobile and dynamic scenarios.

Technology-Driven, Highly-Scalable Dragonfly Topology

Abstract: Evolving technology and increasing pin-bandwidth motivate the use of high-radix routers to reduce the diameter, latency, and cost of interconnection networks. High-radix networks, however, require longer cables than their low-radix counterparts. Because cables dominate network cost, the number of cables, and particularly the number of long, global cables should be minimized to realize an efficient network. In this paper, we introduce the dragonfly topology which uses a group of high-radix routers as a virtual router to increase the effective radix of the network. With this organization, each minimally routed packet traverses at most one global channel. By reducing global channels, a dragonfly reduces cost by 20% compared to a flattened butterfly and by 52% compared to a folded Clos network in configurations with ≥ 16K nodes.We also introduce two new variants of global adaptive routing that enable load-balanced routing in the dragonfly. Each router in a dragonfly must make an adaptive routing decision based on the state of a global channel connected to a different router. Because of the indirect nature of this routing decision, conventional adaptive routing algorithms give degraded performance. We introduce the use of selective virtual-channel discrimination and the use of credit round-trip latency to both sense and signal channel congestion. The combination of these two methods gives throughput and latency that approaches that of an ideal adaptive routing algorithm.

Regional congestion awareness for load balance in networks-on-chip

Abstract: Interconnection networks-on-chip (NOCs) are rapidly replacing other forms of interconnect in chip multiprocessors and system-on-chip designs. Existing interconnection networks use either oblivious or adaptive routing algorithms to determine the route taken by a packet to its destination. Despite somewhat higher implementation complexity, adaptive routing enjoys better fault tolerance characteristics, increases network throughput, and decreases latency compared to oblivious policies when faced with non-uniform or bursty traffic. However, adaptive routing can hurt performance by disturbing any inherent global load balance through greedy local decisions. To improve load balance in adapting routing, we propose Regional Congestion Awareness (RCA), a lightweight technique to improve global network balance. Instead of relying solely on local congestion information, RCA informs the routing policy of congestion in parts of the network beyond adjacent routers. Our experiments show that RCA matches or exceeds the performance of conventional adaptive routing across all workloads examined, with a 16% average and 71% maximum latency reduction on SPLASH-2 benchmarks running on a 49-core CMP. Compared to a baseline adaptive router, RCA incurs a negligible logic and modest wiring overhead.

Routing Metrics and Protocols for Wireless Mesh Networks

Abstract: WMNs are low-cost access networks built on cooperative routing over a backbone composed of stationary wireless routers. WMNs must deal with the highly unstable wireless medium. Therefore, the design of algorithms that consider link quality to choose the best routes are enabling routing metrics and protocols to evolve. In this work, we analyze the state of the art in WMN metrics and propose a taxonomy for WMN routing protocols. Performance measurements for a WMN, deployed using various routing metrics, are presented and corroborate our analysis.

Streamlined packet forwarding using dynamic filters for routing and security in a shared forwarding plane

Abstract: A network router includes a plurality of interfaces configured to send and receive packets, and a routing component comprising: (i) a routing engine that includes a control unit that executes a routing protocol to maintain routing information specifying routes through a network, and (ii) a forwarding plane configured by the routing engine to select next hops for the packets in accordance with the routing information. The forwarding plane comprises a switch fabric to forward the packets to the interfaces based on the selected next hops. The network router also includes a security plane configured to apply security functions to the packets. The security plane is integrated within the network router to share a streamlined forwarding plane of the routing component.

An overview of routing optimization for internet traffic engineering

Abstract: Traffic engineering is an important mechanism for Internet network providers seeking to optimize network performance and traffic delivery. Routing optimization plays a key role in traffic engineering, finding efficient routes so as to achieve the desired network performance. In this survey we review Internet traffic engineering from the perspective of routing optimization. A taxonomy of routing algorithms in the literature is provided, dating from the advent of the TE concept in the late 1990s. We classify the algorithms into multiple dimensions: unicast/multicast, intra-/inter- domain, IP-/MPLS-based and offline/online TE schemes. In addition, we investigate some important traffic engineering issues, including robustness, TE interactions, and interoperability with overlay selfish routing. In addition to a review of existing solutions, we also point out some challenges in TE operation and important issues that are worthy of investigation in future research activities.

New dynamic programming algorithms for the resource constrained shortest path problem.

Abstract: The resource constrained elementary shortest path problem (RCESPP) arises as a pricing subproblem in branch-and-price algorithms for vehicle routing problems with additional constraints. We address the optimization of the RCESPP and we present and compare three methods. The frst method is a well-known exact dynamic programming algorithm improved by new ideas, such as bi-directional search with resource-based bounding. The second method consists of a branch-and-bound algorithm, where lower bounds are computed by dynamic programming with state space relaxation; we show how bounded bi-directional search can be adapted to state space relaxation and we present different branching strategies and their hybridization. The third method, called decremental state space relaxation, is a new one; exact dynamic programming and state space relaxation are two special cases of this new method. The experimental comparison of the three methods is defnitely favourable to decremental state space relaxation. Computational results are given for different kinds of resources, arising from the capacitated vehicle routing problem, the vehicle routing problem with distribution and collection and the vehicle routing problem with capacities and time windows

A reconfigurable routing algorithm for a fault-tolerant 2D-Mesh Network-on-Chip

Abstract: In this paper we present a reconfigurable routing algorithm for a 2D-mesh network-on-chip (NoC) dedicated to fault- tolerant, massively parallel multi-processors systems on chip (MP2-SoC). The routing algorithm can be dynamically reconfigured, to adapt to the modification of the micro-network topology caused by a faulty router. This algorithm has been implemented in a reconfigurable version of the DSPIN micro-network, and evaluated from the point of view of performance (penalty on the network saturation threshold), and cost (extra silicon area occupied by the reconfigurable version of the router).

Multiconstrained QoS multipath routing in wireless sensor networks

Abstract: Sensor nodes are densely deployed to accomplish various applications because of the inexpensive cost and small size. Depending on different applications, the traffic in the wireless sensor networks may be mixed with time-sensitive packets and reliability-demanding packets. Therefore, QoS routing is an important issue in wireless sensor networks. Our goal is to provide soft-QoS to different packets as path information is not readily available in wireless networks. In this paper, we utilize the multiple paths between the source and sink pairs for QoS provisioning. Unlike E2E QoS schemes, soft-QoS mapped into links on a path is provided based on local link state information. By the estimation and approximation of path quality, traditional NP-complete QoS problem can be transformed to a modest problem. The idea is to formulate the optimization problem as a probabilistic programming, then based on some approximation technique, we convert it into a deterministic linear programming, which is much easier and convenient to solve. More importantly, the resulting solution is also one to the original probabilistic programming. Simulation results demonstrate the effectiveness of our approach.

Packet caches on routers: the implications of universal redundant traffic elimination

Abstract: Many past systems have explored how to eliminate redundant transfers from network links and improve network efficiency. Several of these systems operate at the application layer, while the more recent systems operate on individual packets. A common aspect of these systems is that they apply to localized settings, e.g. at stub network access links. In this paper, we explore the benefits of deploying packet-level redundant content elimination as a universal primitive on all Internet routers. Such a universal deployment would immediately reduce link loads everywhere. However, we argue that far more significant network-wide benefits can be derived by redesigning network routing protocols to leverage the universal deployment. We develop "redundancy-aware" intra- and inter-domain routing algorithms and show that they enable better traffic engineering, reduce link usage costs, and enhance ISPs' responsiveness to traffic variations. In particular, employing redundancy elimination approaches across redundancy-aware routes can lower intra and inter-domain link loads by 10-50%. We also address key challenges that may hinder implementation of redundancy elimination on fast routers. Our current software router implementation can run at OC48 speeds.

Implementation and Analysis of a New Selection Strategy for Adaptive Routing in Networks-on-Chip

Abstract: Efficient and deadlock-free routing is critical to the performance of networks-on-chip. The effectiveness of any adaptive routing algorithm strongly depends on the underlying selection strategy. A selection function is used to select the output channel where the packet will be forwarded on. In this paper we present a novel selection strategy that can be coupled with any adaptive routing algorithm. The proposed selection strategy is based on the concept of Neighbors-on-Path the aims of which is to exploit the situations of indecision occurring when the routing function returns several admissible output channels. The overall objective is to choose the channel that will allow the packet to be routed to its destination along a path that is as free as possible of congested nodes. Performance evaluation is carried out by using a flit-accurate simulator under traffic scenarios generated by both synthetic and real applications. Results obtained show how the proposed selection strategy applied to the Odd-Even routing algorithm yields an improvement in both average delay and saturation point up to 20% and 30% on average respectively, with a minimal overhead in terms of area occupation. In addition, a positive effect on total energy consumption is also observed under near-congestion packet injection rates.

Toward internet-wide multipath routing

Abstract: The Internet would be more efficient and robust if routers could flexibly divide traffic over multiple paths. Often, having one or two extra paths is sufficient for customizing paths for different applications, improving security, reacting to failures, and balancing load. However, support for Internet-wide multipath routing faces two significant barriers. First, multipath routing could impose significant computational and storage overhead in a network the size of the Internet. Second, the independent networks that comprise the Internet will not relinquish control over the flow of traffic without appropriate incentives. In this article, we survey flexible multipath routing techniques that are both scalable and incentive compatible. Techniques covered include: multihoming, tagging, tunneling, and extensions to existing Internet routing protocols.

Method and apparatus for automatic inter-domain routing of calls

Abstract: A method and apparatus for inter-domain routing of calls in a network, where the network represents a first wide area network. A routing node of the network advertises its access to a range of addresses in a second wide area network and a cost for access to the range of addresses to all adjacent nodes in the network. Each of the adjacent nodes inserts an entry in its own routing table associating access to the range of addresses in the second wide area network with the network address of the routing node and the cost for access. Each adjacent node then modifies the cost for access by adding its own cost and advertises its access to the range of addresses in the second wide area network and the modified cost for access to all of its adjacent nodes. When a call addressed to a destination address in the range of address in the second wide area network is received at each node of the network, then the node searches for the entry in its routing table corresponding to the range of addresses in the second wide area network having the lowest cost for access and connects the call to the adjacent node associated with the entry having the lowest cost. The routing node can also advertise one or more protocol types which it can support, where the protocol types are associated with the routing node in the routing table in each adjacent node and a call having a given protocol type is also routed at each node of the network based upon its protocol type.

Distributed energy-efficient cooperative routing in wireless networks

Abstract: 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.

Controlling the spread of interests and content in a content centric network

Abstract: One embodiment of the present invention provides a system for controlling the spread of interests and content in a content centric network (CCN). During operation, the system maintains a routing policy for content data. The system also receives a packet associated with a piece of content or an interest for the content. Next, the system determines that the structured name included in the packet is within the namespace specified in the routing policy. The system further determines that the packet satisfies the condition in the routing policy. Subsequently, the system routes the packet based on in part the action corresponding to the condition as specified in the routing policy.

Optimal routing and data aggregation for maximizing lifetime of wireless sensor networks

Abstract: An optimal routing and data aggregation scheme for wireless sensor networks is proposed in this paper. The objective is to maximize the network lifetime by jointly optimizing data aggregation and routing. We adopt a model to integrate data aggregation with the underlying routing scheme and present a smoothing approximation function for the optimization problem. The necessary and sufficient conditions for achieving the optimality are derived and a distributed gradient algorithm is designed accordingly. We show that the proposed scheme can significantly reduce the data traffic and improve the network lifetime. The distributed algorithm can converge to the optimal value efficiently under all network configurations.

Spectrum Aware Routing for Multi-Hop Cognitive Radio Networks with a Single Transceiver

Abstract: In multi-hop single transceiver Cognitive Radio networks (MSCRN), routing becomes of great challenge when IEEE 802.11 DCF is used as the MAC protocol. Routing should not base on common control channel because it is not ensured that common control channel can be obtained by each node. In this paper, we propose a spectrum aware on-demand routing which doesn't base on control channel. A channel assignment algorithm aimed at improving link utilization is derived from delay-analysis. The overhead and gain by switching are balanced in this algorithm. For deafness problem caused by switching can result in significant performance degradation, constraints to avoid the appearance of deafness in channel assignment process are given. We stress that our approach can be easily implemented for the using of standard IEEE 802.11DCF. Results of simulation show that, our approach can well fit MSCRN and improve the network throughput comparing to the same network scenario without cognitive ability.

Method, system, and computer program product for managing routing servers and services

Abstract: A method, system, and computer program product for routing network traffic (calls in a Voice over Internet Protocol (VoIP)), which expands the capabilities of existing systems by providing faster and more efficient direction of network traffic, is disclosed. A routing management system includes a routing manager which maintains a list of local routes, establishes and manages connections to the routing server(s), exports routes to the routing server(s), imports disseminated routes from the routing server(s), obtains static global and dynamic routes from the routing server(s), caches those routes for future use, finds all matching routes for a particular number dialed by the user, and prioritizing those routes based on timing, access and ordering information. An additional embodiment contains at least one routing server which provides look-up services for gateway server(s), allows export of local routes from gateway server(s), and distributes translation data; and at least one gateway server which handles calls received on either the Internet protocol (IP) or traditional telephony networks. The gateway server bridges calls between the different kinds of networks, interacts with users, interfaces with the routing system.

STOD-RP: A Spectrum-Tree Based On-Demand Routing Protocol for Multi-Hop Cognitive Radio Networks

Abstract: A unique challenge for routing in cognitive radio networks is the collaboration between the route selection and spectrum decision. To solve this problem, in this paper a Spectrum-Tree base On-Demand routing protocol (STOD-RP) is proposed where a spectrum-tree is built in each spectrum band. The formation of the spectrum-tree addresses the cooperation between spectrum decision and route selection in an efficient way. In addition, a new route metric is proposed as well as a fast and efficient spectrum-adaptive route recovery method. Simulation results show that our proposed STOD-RP reduces the control overhead and shortens the average end-to-end delay significantly.

Ad hoc networks beyond unit disk graphs

Abstract: In this paper, we study an algorithmic model for wireless ad hoc and sensor networks that aims to be sufficiently close to reality as to represent practical real-world networks while at the same time being concise enough to promote strong theoretical results The quasi unit disk graph model contains all edges shorter than a parameter d between 0 and 1 and no edges longer than 1 We show that--in comparison to the cost known for unit disk graphs--the complexity results of geographic routing in this model contain the additional factor 1/d2 We prove that in quasi unit disk graphs flooding is an asymptotically message-optimal routing technique, we provide a geographic routing algorithm being most efficient in dense networks, and we show that classic geographic routing is possible with the same asymptotic performance guarantees as for unit disk graphs if d ≥ 1/√2

Design Guidelines for Routing Metrics in Multihop Wireless Networks

Abstract: The design of a routing protocol must be based on the characteristics of its target networks. The diversity of wireless networks motivates the design of different routing metrics, capturing different aspects of wireless communications. The design of routing metrics, however, is not arbitrary since it has a great impact on the proper operation of routing protocols. Combining a wrong type of routing metrics with a routing protocol may result in routing loops and suboptimal paths. In this paper, we thoroughly study the relationship between routing metrics and routing protocols. Our work provides important guidelines for designing routing metrics and identifies the specific properties that a routing metric must have in order to be combined with certain type of routing protocols.

Consensus routing: the internet as a distributed system

Abstract: Internet routing protocols (BGP, OSPF, RIP) have traditionally favored responsiveness over consistency. A router applies a received update immediately to its forwarding table before propagating the update to other routers, including those that potentially depend upon the outcome of the update. Responsiveness comes at the cost of routing loops and blackholes--a router A thinks its route to a destination is via B but B disagrees. By favoring responsiveness (a liveness property) over consistency (a safety property), Internet routing has lost both. Our position is that consistent state in a distributed system makes its behavior more predictable and securable. To this end, we present consensus routing, a consistency-first approach that cleanly separates safety and liveness using two logically distinct modes of packet delivery: a stable mode where a route is adopted only after all dependent routers have agreed upon it, and a transient mode that heuristically forwards the small fraction of packets that encounter failed links. Somewhat surprisingly, we find that consensus routing improves overall availability when used in conjunction with existing transient mode heuristics such as backup paths, deflections, or detouring. Experiments on the Internet's AS-level topology show that consensus routing eliminates nearly all transient disconnectivity in BGP.

Systems and methods for adaptive routing in mobile ad-hoc networks and disruption tolerant networks

Abstract: The systems and methods described herein include adaptive routing processes for packet-based wireless communication networks. This routing approach works both in MANETs (when a contemporaneous end-to-end path is available) and in DTNs (when a contemporaneous end to end path is not available, but one of formed over space and time). In particular, the methods include adaptively selecting a routing process for transmitting a packet through a node in the network based on available information on the network topology and/or the contents of the packet.

Remote Message Routing Device and Methods Thereof

Abstract: A message routing method includes receiving a plurality of messages at a routing node. The routing node is configured to receive instructions indicating an offset, criteria associated with the offset, and a group of interested nodes. The routing node examines a portion of a data payload of a received message based on the offset. If the information at the offset matches the criteria, the routing node routes the message to each of the group of interested nodes. Thus, the routing node can route messages to different groups of destination nodes depending on information in the data payload of received messages, thereby providing a flexible way to route messages over a network.

A tabu search algorithm for the periodic vehicle routing problem with multiple vehicle trips and accessibility restrictions

Abstract: In this paper, we consider a periodic vehicle routing problem that includes, in addition to the classical constraints, the possibility of a vehicle doing more than one route per day, as long as the maximum daily operation time for the vehicle is not exceeded. In addition, some constraints relating to accessibility of the vehicles to the customers, in the sense that not every vehicle can visit every customer, must be observed. We refer to the problem we consider here as the site-dependent multi-trip periodic vehicle routing problem. An algorithm based on tabu search is presented for the problem and computational results presented on randomly generated test problems that are made publicly available. Our algorithm is also tested on a number of routing problems from the literature that constitute particular cases of the proposed problem. Specifically we consider the periodic vehicle routing problem; the site-dependent vehicle routing problem; the multi-trip vehicle routing problem; and the classical vehicle routing problem. Computational results for our tabu search algorithm on test problems taken from the literature for all of these problems are presented.

Randomized 3D Geographic Routing

Abstract: We reconsider the problem of geographic routing in wireless ad hoc networks. We are interested in local, memoryless routing algorithms, i.e. each network node bases its routing decision solely on its local view of the network, nodes do not store any message state, and the message itself can only carry information about O(1) nodes. In geographic routing schemes, each network node is assumed to know the coordinates of itself and all adjacent nodes, and each message carries the coordinates of its target. Whereas many of the aspects of geographic routing have already been solved for 2D networks, little is known about higher-dimensional networks. It has been shown only recently that there is in fact no local memoryless routing algorithm for 3D networks that delivers messages deterministically. In this paper, we show that a cubic routing stretch constitutes a lower bound for any local memoryless routing algorithm, and propose and analyze several randomized geographic routing algorithms which work well for 3D network topologies. For unit ball graphs, we present a technique to locally capture the surface of holes in the network, which leads to 3D routing algorithms similar to the greedy-face-greedy approach for 2D networks.