Showing papers on "Equal-cost multi-path routing published in 2011"

OpenFlow for Wireless Mesh Networks

Abstract: everal protocols for routing and forwarding in Wireless Mesh Networks (WMN) have been proposed, such as AODV, OLSR or B.A.T.M.A.N. However, providing support for e.g. flow-based routing where flows of one source take different paths through the network is hard to implement in a unified way using traditional routing protocols. OpenFlow is an emerging technology which makes network elements such as routers or switches programmable via a standardized interface. By using virtualization and flow-based routing, OpenFlow enables a rapid deployment of novel packet forwarding and routing algorithms, focusing on fixed networks. We propose an architecture that integrates OpenFlow with WMNs and provides such flow-based routing and forwarding capabilities. To demonstrate the feasibility of our OpenFlow based approach, we have implemented a simple solution to solve the problem of client mobility in a WMN which handles the fast migration of client addresses (e.g. IP addresses) between Mesh Access Points and the interaction with re-routing without the need for tunneling. Measurements from a real mesh testbed (KAUMesh) demonstrate the feasibility of our approach based on the evaluation of forwarding performance, control traffic and rule activation time.

On combining shortest-path and back-pressure routing over multihop wireless networks

Abstract: Back-pressure-type algorithms based on the algorithm by Tassiulas and Ephremides have recently received much attention for jointly routing and scheduling over multihop wireless networks. However, this approach has a significant weakness in routing because the traditional back-pressure algorithm explores and exploits all feasible paths between each source and destination. While this extensive exploration is essential in order to maintain stability when the network is heavily loaded, under light or moderate loads, packets may be sent over unnecessarily long routes, and the algorithm could be very inefficient in terms of end-to-end delay and routing convergence times. This paper proposes a new routing/scheduling back-pressure algorithm that not only guarantees network stability (throughput optimality), but also adaptively selects a set of optimal routes based on shortest-path information in order to minimize average path lengths between each source and destination pair. Our results indicate that under the traditional back-pressure algorithm, the end-to-end packet delay first decreases and then increases as a function of the network load (arrival rate). This surprising low-load behavior is explained due to the fact that the traditional back-pressure algorithm exploits all paths (including very long ones) even when the traffic load is light. On the other-hand, the proposed algorithm adaptively selects a set of routes according to the traffic load so that long paths are used only when necessary, thus resulting in much smaller end-to-end packet delays as compared to the traditional back-pressure algorithm .

Social-aware stateless forwarding in pocket switched networks

Abstract: In this paper we describe SANE, the first forwarding mechanism that combines the advantages of both social-aware and stateless approaches in pocket switched network routing. SANE is based on the observation“that we validate on real-world traces”that individuals with similar interests tend to meet more often. In our approach, individuals (network members) are characterized by their interest profile, a compact representation of their interests. Through extensive experiments, we show the superiority of social-aware, stateless forwarding over existing stateful, social-aware and stateless, social-oblivious forwarding. An important byproduct of our interest-based approach is that it easily enables innovative routing primitives, such as interest-casting. An interest-casting protocol is also described, and extensively evaluated through experiments based on both real-world and synthetic mobility traces.

Intersection-Based Geographical Routing Protocol for VANETs: A Proposal and Analysis

Abstract: This paper presents a class of routing protocols for vehicular ad hoc networks (VANETs) called the Intersection-based Geographical Routing Protocol (IGRP), which outperforms existing routing schemes in city environments. IGRP is based on an effective selection of road intersections through which a packet must pass to reach the gateway to the Internet. The selection is made in a way that guarantees, with high probability, network connectivity among the road intersections while satisfying quality-of-service (QoS) constraints on tolerable delay, bandwidth usage, and error rate. Geographical forwarding is used to transfer packets between any two intersections on the path, reducing the path's sensitivity to individual node movements. To achieve this, we mathematically formulate the QoS routing problem as a constrained optimization problem. Specifically, analytical expressions for the connectivity probability, end-to-end delay, hop count, and bit error rate (BER) of a route in a two-way road scenario are derived. Then, we propose a genetic algorithm to solve the optimization problem. Numerical and simulation results show that the proposed approach gives optimal or near-optimal solutions and significantly improves VANET performance when compared with several prominent routing protocols, such as greedy perimeter stateless routing (GPSR), greedy perimeter coordinator routing (GPCR), and optimized link-state routing (OLSR).

Link-state routing with hop-by-hop forwarding can achieve optimal traffic engineering

Abstract: This paper settles an open question with a positive answer: Optimal traffic engineering (or optimal multicommodity flow) can be realized using just link-state routing protocols with hop-by-hop forwarding. Today's typical versions of these protocols, Open Shortest Path First (OSPF) and Intermediate System-Intermediate System (IS-IS), split traffic evenly over shortest paths based on link weights. However, optimizing the link weights for OSPF/IS-IS to the offered traffic is a well-known NP-hard problem, and even the best setting of the weights can deviate significantly from an optimal distribution of the traffic. In this paper, we propose a new link-state routing protocol, PEFT, that splits traffic over multiple paths with an exponential penalty on longer paths. Unlike its predecessor, DEFT, our new protocol provably achieves optimal traffic engineering while retaining the simplicity of hop-by-hop forwarding. The new protocol also leads to a significant reduction in the time needed to compute the best link weights. Both the protocol and the computational methods are developed in a conceptual framework, called Network Entropy Maximization, that is used to identify the traffic distributions that are not only optimal, but also realizable by link-state routing.

Source routing convergence in constrained computer networks

Abstract: In one embodiment, a source routing device (e.g., root device) pre-computes diverse source-routed paths to one or more nodes in a computer network. Upon receiving a particular packet, the device forwards the particular packet on a source-routed first path of the pre-computed diverse paths. In the event the device implicitly detects failure of the first path, then it forwards a copy of the particular packet on a source-routed second path of the pre-computed diverse paths in response. In one embodiment, implicit failure detection comprises seeing a second (repeated) packet with the same identification within a certain time since the first packet, and the second packet is forwarded on the second path. In another embodiment, implicit failure detection comprises not seeing a link-layer acknowledgment returned or receiving an error notification from a node along the broken path, and a stored copy of the particular packet is forwarded on the second path.

Geographical Routing With Location Service in Intermittently Connected MANETs

Abstract: Combining mobile platforms such as manned or unmanned vehicles and peer-assisted wireless communication is an enabler for a vast number of applications. A key enabler for the applications is the routing protocol that directs the packets in the network. Routing packets in fully connected mobile ad hoc networks (MANETs) has been studied to a great extent, but the assumption on full connectivity is generally not valid in a real system. This case means that a practical routing protocol must handle intermittent connectivity and the absence of end-to-end connections. In this paper, we propose a geographical routing algorithm called location-aware routing for delay-tolerant networks (LAROD), enhanced with a location service, location dissemination service (LoDiS), which together are shown to suit an intermittently connected MANET (IC-MANET). Because location dissemination takes time in IC-MANETs, LAROD is designed to route packets with only partial knowledge of geographic position. To achieve low overhead, LAROD uses a beaconless strategy combined with a position-based resolution of bids when forwarding packets. LoDiS maintains a local database of node locations, which is updated using broadcast gossip combined with routing overhearing. The algorithms are evaluated under a realistic application, i.e., unmanned aerial vehicles deployed in a reconnaissance scenario, using the low-level packet simulator ns-2. The novelty of this paper is the illustration of sound design choices in a realistic application, with holistic choices in routing, location management, and the mobility model. This holistic approach justifies that the choice of maintaining a local database of node locations is both essential and feasible. The LAROD-LoDiS scheme is compared with a leading delay-tolerant routing algorithm (spray and wait) and is shown to have a competitive edge, both in terms of delivery ratio and overhead. For spray and wait, this case involved a new packet-level implementation in ns-2 as opposed to the original connection-level custom simulator.

Model and Protocol for Energy-Efficient Routing over Mobile Ad Hoc Networks

Abstract: Many minimum energy (energy-efficient) routing protocols have been proposed in recent years. However, very limited effort has been made in studying routing overhead, route setup time, and route maintenance issues associated with these protocols. Without a careful design, an energy-efficient routing protocol can perform much worse than a normal routing protocol. In this paper, we first show that the minimum energy routing schemes in the literature could fail without considering the routing overhead involved and node mobility. We then propose a more accurate analytical model to track the energy consumptions due to various factors, and a simple energy-efficient routing scheme PEER to improve the performance during path discovery and in mobility scenarios. Our simulation results indicate that compared to a conventional energy-efficient routing protocol, PEER protocol can reduce up to 2/3 path discovery overhead and delay, and 50 percent transmission energy consumption.

On the feasibility and efficacy of protection routing in IP networks

Abstract: With network components increasingly reliable, routing is playing an ever greater role in determining network reliability. This has spurred much activity in improving routing stability and reaction to failures and rekindled interest in centralized routing solutions, at least within a single routing domain. Centralizing decisions eliminates uncertainty and many inconsistencies and offers added flexibility in computing routes that meet different criteria. However, it also introduces new challenges, especially in reacting to failures where centralization can increase latency. This paper leverages the flexibility afforded by centralized routing to address these challenges. Specifically, we explore when and how standby backup forwarding options can be activated while waiting for an update from the centralized server after the failure of an individual component (link or node). We provide analytical insight into the feasibility of such backups as a function of network structure and quantify their computational complexity. We also develop an efficient heuristic reconciling protectability and performance, and demonstrate its effectiveness in a broad range of scenarios. The results should facilitate deployments of centralized routing solutions.

An abacus turn model for time/space-efficient reconfigurable routing

Abstract: Applications' traffic tends to be bursty and the location of hot-spot nodes moves as time goes by. This will significantly aggregate the blocking problem of wormhole-routed Network-on-Chip (NoC). Most of state-of-the-art traffic balancing solutions are based on fully adaptive routing algorithms which may introduce large time/space overhead to routers. Partially adaptive routing algorithms, on the other hand, are time/space efficient, but lack of even or sufficient routing adaptiveness. Reconfigurable routing algorithms could provide on-demand routing adaptiveness for reducing blocking, but most of them are off-line solutions due to the lack of a practical model to dynamically generate deadlock-free routing algorithms. In this paper, we propose the abacus-turn-model (AbTM) for designing time/space-efficient reconfigurable wormhole routing algorithms. Unlike the original turn model, AbTM exploits dynamic communication patterns in applications to reduce the routing latency and chip area requirements. We apply forbidden turns dynamically to preserve deadlock-free operations. Our AbTM routing architecture has two distinct advantages: First, the AbTM leads to a new router architecture without adding virtual channels and routing table. This reconfigurable architecture updates the routing path once the communication pattern changes, and always provides full adaptiveness to hot-spot directions to reduce network blocking. Secondly, the reconfiguration scheme has a good scalability because all operations are carried out between neighbors. We demonstrate these advantages through extensive simulation experiments. The experimental results are indeed encouraging and prove its applicability with scalable performance in large-scale NoC applications.

A SimPLR method for routability-driven placement

Abstract: Highly-optimized placements may lead to irreparable routing congestion due to inadequate models of modern interconnect stacks and the impact of partial routing obstacles. Additional challenges in routability-driven placement include scalability to large netlists and limiting the complexity of software integration. Addressing these challenges, we develop lookahead routing to give the placer advance, firsthand knowledge of trouble spots, not distorted by crude congestion models. We also extend global placement to (i) spread cells apart in congested areas, and (ii) move cells together in less-congested areas to ensure short, routable interconnects and moderate runtime. While previous work adds isolated steps to global placement, our SIMultaneous PLace-and-Route tool SimPLR integrates a layer- and via-aware global router into a leading-edge, force-directed placer. The complexity of integration is mitigated by careful design of simple yet effective optimizations. On the ISPD 2011 Contest Benchmark Suite, with the official evaluation protocol, SimPLR outperforms every contestant on every benchmark.

Methods, systems, and computer readable media for providing dynamic origination-based routing key registration in a diameter network

Abstract: Methods, systems, and computer readable media for providing dynamic origination-based routing key registration in a DIAMETER network are disclosed. According to one method, origin-based routing information is received, at a first DIAMETER node, from a second DIAMETER node. The origin-based routing information specifies one or more sources such that traffic originating from one of the one or more sources should be routed to the second DIAMETER node. A routing rule is automatically generated, at he first DIAMETER node, based on the received origin-based routing information.

A geographical routing protocol for highly-dynamic aeronautical networks

Abstract: Emerging networked systems require domain-specific routing protocols to cope with the challenges faced by the aeronautical environment. We present a geographic routing protocol AeroRP for multihop routing in highly dynamic MANETs. The AeroRP algorithm uses velocity-based heuristics to deliver the packets to destinations in a multi-Mach speed environment. Furthermore, we present the decision metrics used to forward the packets by the various AeroRP operational modes. The analysis of the ns-3 simulations shows AeroRP has several advantages over other MANET routing protocols in terms of PDR, accuracy, delay, and overhead. Moreover, AeroRP offers performance tradeoffs in the form of different AeroRP modes.

Forwarding anomalies in Bloom filter-based multicast

Abstract: Several recently proposed multicast protocols use in-packet Bloom filters to encode multicast trees. These mechanisms are in principle highly scalable because no per-flow state is required in the routers and because routing decisions can be made efficiently by simply checking for the presence of outbound links in the filter. Yet, the viability of previous approaches is limited by the possibility of forwarding anomalies caused by false positives inherent in Bloom filters. This paper explores such anomalies, namely (1) packets storms, (2) forwarding loops and (3) flow duplication. We propose stateless solutions that increase the robustness and the scalability of Bloom filter-based multicast protocols. In particular, we show that the parameters of the filter need to be varied to guarantee the stability of the packet forwarding, and we present a bit permutation technique that effectively prevents both accidental and maliciously created anomalies. We evaluate our solutions in the context of BloomCast, a source-specific inter-domain multicast protocol, using analytical methods and simulations.

Adaptive Routing in Network-on-Chips Using a Dynamic-Programming Network

Abstract: Dynamic routing is desirable because of its substantial improvement in communication bandwidth and intelligent adaptation to faulty links and congested traffic. However, implementation of adaptive routing in a network-on-chip system is not trivial and is further complicated by the requirements of deadlock-free and real-time optimal decision making. In this paper, we present a deadlock-free routing architecture which employs a dynamic programming (DP) network to provide on-the-fly optimal path planning and network monitoring for packet switching. Also, a new routing strategy called k-step look ahead is introduced. This new strategy can substantially reduce the size of routing table and maintain a high quality of adaptation which leads to a scalable dynamic-routing solution with minimal hardware overhead. Our results, based on a cycle-accurate simulator, demonstrate the effectiveness of the DP network, which outperforms both the deterministic and adaptive-routing algorithms in average delay on various traffic scenarios by 22.3%. Moreover, the hardware overhead for DP network is insignificant, based on the results obtained from the hardware implementations.

A Comprehensive Performance Analysis of Proactive, Reactive and Hybrid MANETs Routing Protocols

Abstract: A mobile Ad-hoc network (MANET) is a dynamic multi hop wireless network established by a group of nodes in which there is no central administration. Due to mobility of nodes and dynamic network topology, the routing is one of the most important challenges in ad-hoc networks. Several routing algorithms for MANETs have been proposed by the researchers which have been classified into various categories, however, the most prominent categories are proactive, reactive and hybrid. The performance comparison of routing protocols for MANETs has been presented by other researcher also, however, none of these works considers proactive, reactive and hybrid protocols together. In this paper, the performance of proactive (DSDV), reactive (DSR and AODV) and hybrid (ZRP) routing protocols has been compared. The performance differentials are analyzed on the basis of throughput, average delay, routing overhead and number of packets dropped with a variation of number of nodes, pause time and mobility.

Routing policies in named data networking

Abstract: Modern inter-domain routing with BGP is based on policies rather than finding shortest paths. Network operators devise and implement policies affecting route selection and export independently of others. These policies are realized by tuning a variety of parameters, or knobs, present in BGP. Similarly, NDN, a information-centric future Internet architecture, will utilize a policy-based routing protocol such as BGP. However, NDN allows a finer granularity of policies (content names rather than hosts) and more traffic engineering opportunities.This work explores what routing policies could look like in an NDN Internet. We describe the knobs available to network operators and their possible settings. Furthermore, we explore the economic incentives present in an NDN Internet and reason how they might drive operators to set their policies.

Systems and methods for policy based routing for multiple next hops

Abstract: The present application is directed towards policy based routing for intelligent traffic management via multiple next hops. In some embodiments, the systems and methods disclosed herein may provide management of inbound and outbound traffic across multiple network links, and may further provide reliability in case of link failure, and provide balancing of traffic, responsive to the latency and bandwidth requirements of various applications. Accordingly, these systems and methods may provide intelligent policy-based routing and network and port address translation, sensitive to application traffic types, protocols, source IP addresses and ports, destination IP addresses and ports, or any combination thereof, and can balance traffic loads among multiple available paths based on multiple traffic characteristics. The routing may performed on a packet-by-packet basis, a transaction-by-transaction basis, or a session-by-session basis, and the systems and methods may include capabilities for application-aware health monitoring of available network paths.

Inter-domain routing in an n-ary-tree and source-routing based communication framework

Abstract: Systems and techniques for processing and forwarding packets are described. Specifically, some embodiments can include a receiving mechanism, a determining mechanism, a generating mechanism, and a sending mechanism. The receiving mechanism can be configured to receive a first packet that is to be routed from a first node in a first Autonomous System (AS) to a second node in a second AS. The determining mechanism can be configured to determine a set of bits that encodes a route in an n-ary tree that includes the first node and a root node in the first AS. The generating mechanism can be configured to generate, based on the first packet, a second packet that includes the set of bits and an identifier associated with the second AS. The sending mechanism can be configured to send the second packet.

The period vehicle routing problem: New heuristics and real-world variants

Abstract: We develop a heuristic for the period vehicle routing problem that uses an integer program and the record-to-record travel algorithm. Our heuristic produces very high-quality results on standard benchmark instances. We extend our heuristic to handle real-world routing considerations that involve reassigning customers to new routes and balancing the workload among drivers across routes. We demonstrate how these new variants can be used by managers to generate effective routes in practice.

Intersection-Based Routing Protocol for VANETs

Abstract: Vehicular ad hoc network (VANET) is an emerging wireless communications technology that is capable of enhancing driving safety and velocity by exchanging real-time transportation information. In VANETs, the carry-and-forward strategy has been adopted to overcome uneven distribution of vehicles. If the next vehicle located is in transmission range, then the vehicle forwards the packets; if not, then it carries the packets until meeting. The carry mostly occurs on sparsely populated road segments, with long carry distances having long end-to-end packet delays. Similarly, the dense condition could have long delays, due to queuing delays. The proposed intersection-based routing protocol finds a minimum delay routing path in various vehicle densities. Moreover, vehicles reroute each packet according to real-time road conditions in each intersection, and the packet routing at the intersections is dependent on the moving direction of the next vehicle. Finally, the simulation results show that the proposed Intersection-Based Routing (IBR) protocol has less end-to-end delay compared to vehicle-assisted data delivery (VADD) and greedy traffic aware routing protocol (GyTAR) protcols.

M-DART: multi-path dynamic address routing

Abstract: The paper proposes a Distributed Hash Table (DHT)-based multi-path routing protocol for scalable ad hoc networks. Specifically, we propose a multipath-based improvement to a recently proposed DHT-based shortest-path routing protocol, namely the Dynamic Address RouTing (DART). The resulting protocol, referred to as multi-path DART (M-DART), guarantees multi-path forwarding without introducing any additional communication or coordination overhead with respect to DART. The performances of M-DART have been evaluated by means of numerical simulations across a wide range of environments and workloads. The results show that M-DART performs the best or at least comparable with respect to widely adopted routing protocols in all the considered scenarios. Moreover, unlike these protocols, it is able to assure satisfactory performances for large networks by reducing the packet loss by up to 75%. Copyright © 2010 John Wiley & Sons, Ltd. (This work is partially supported by the Italian National Project ‘Global & Reliable End to End e-Commerce & On Line Service Platform’ (GRECO).)

A sociability-based routing scheme for delay-tolerant networks

Abstract: The problem of choosing the best forwarders in Delay-Tolerant Networks (DTNs) is crucial for minimizing the delay in packet delivery and for keeping the amount of generated traffic under control. In this paper, we introduce sociable routing, a novel routing strategy that selects a subset of optimal forwarders among all the nodes and relies on them for an efficient delivery. The key idea is that of assigning to each network node a time-varying scalar parameter which captures its social behavior in terms of frequency and types of encounters. This sociability concept is widely discussed and mathematically formalized. Simulation results of a DTN of vehicles in urban environment, driven by real mobility traces, and employing sociable routing, is presented. Encouraging results show that sociable routing, compared to other known protocols, achieves a good compromise in terms of delay performance and amount of generated traffic.

Enhancing Contact Graph Routing for Delay Tolerant Space Networking

Abstract: When designing routing protocols for space-based networks, we must take into consideration the unique characteristics of such networks. Since space-based networks are inherently sparse with constrained resources, one needs to design smart routing algorithms that use the resources efficiently to maximize network performance. In Space Exploration Missions, the trajectories and orbits of spacecraft are predetermined, thus communication opportunities are predictable. This a-priori knowledge can be used to the advantage of scheduling and routing. In this paper, we focus on analyzing Contact Graph Routing (CGR) for space-based networks. CGR makes use of the predictable nature of the contacts to make routing decisions. Mars and Lunar mission-like scenarios were used in our simulations to gather statistics on routing protocol performance in terms of delay and buffer usage. We provide improvements to the underlying cost function of CGR to avoid routing loops and suggest applying Dijkstra's shortest path algorithm for path selection. The cost function change was incorporated into the latest Internet Draft posted for CGR. Dijkstra's shortest path algorithm was successfully implemented and tested in NASA's Interplanetary Overlay Network (ION) implementation of the DTN protocols.

Topology switching for data center networks

Abstract: Emerging data-center network designs seek to provide physical topologies with high bandwidth, large bisection capacities, and many alternative data paths Yet, existing protocols present a one-size-fits-all approach for forwarding packets Traditionally, the routing process chooses one "best" route for each end-point pair While some modern protocols support multiple paths through techniques like ECMP, each path continues to be selected using the same optimization metric However, today's data centers host applications with a diverse universe of networking needs; a single-minded forwarding approach is likely to either let paths go unused, sacrificing reliability and performance, or make the entire network available to all applications, sacrificing needs such as isolation This paper introduces topology switching to return control to individual applications for deciding best how to route data among their nodes Topology switching formalizes the simultaneous use of multiple routing mechanisms in a data center, allowing applications to define multiple routing systems and deploy individualized routing tasks at small time scales We introduce the topology switching abstraction and illustrate how it can provide both network efficiency and individual application performance, and admit flexible network management strategies

Performance Comparison of VANET Routing Protocols

Abstract: Vehicular Ad-hoc Network (VANET) is a collection of communication vehicles, moving in different directions. The vehicles form a communication group to disseminate desired information. Various routing protocols are implemented in a VANET, each having benefits and shortcoming in the domain of implementation. In this paper performance of three routing protocols, namely Ad hoc On-Demand Distance Vector Routing (AODV), Destination Sequenced Distance Vector (DSDV) and Dynamic Source Routing (DSR) is compared for different parameters. The protocols are simulated on Network Simulator-2(ns- 2).