Showing papers on "Equal-cost multi-path routing published in 2014"

A heuristic approach for the green vehicle routing problem with multiple technologies and partial recharges

Abstract: This paper presents several heuristics for a variation of the vehicle routing problem in which the transportation fleet is composed of electric vehicles with limited autonomy in need for recharge during their duties. In addition to the routing plan, the amount of energy recharged and the technology used must also be determined. Constructive and local search heuristics are proposed, which are exploited within a non deterministic Simulated Annealing framework. Extensive computational results on varying instances are reported, evaluating the performance of the proposed algorithms and analyzing the distinctive elements of the problem (size, geographical configuration, recharge stations, autonomy, technologies, etc.).

The Segment Routing Architecture

Abstract: Network operators anticipate the offering of an increasing variety of cloud-based services with stringent Service Level Agreements. Technologies currently supporting IP networks however lack the flexibility and scalability properties to realize such evolution. In this article, we present Segment Routing (SR), a new network architecture aimed at filling this gap, driven by use-cases defined by network operators. SR implements the source routing and tunneling paradigms, letting nodes steer packets over paths using a sequence of instructions (segments) placed in the packet header. As such, SR allows the implementation of routing policies without per-flow entries at intermediate routers. This paper introduces the SR architecture, describes its related ongoing standardization efforts, and reviews the main use-cases envisioned by network operators.

Optimization-Based Adaptive Large Neighborhood Search for the Production Routing Problem

Abstract: Operational problems arising in the planning of integrated supply chains have been increasingly studied in the past decade. Among these, the production routing problem (PRP) is a difficult problem that aims to jointly optimize production, inventory, distribution, and routing decisions in order to satisfy the dynamic demand of customers and minimize the overall system cost. This paper introduces an optimization-based adaptive large neighborhood search heuristic for the PRP. In this heuristic, binary variables representing setup and routing decisions are handled by an enumeration scheme and upper-level search operators, respectively, and continuous variables associated with production, inventory, and shipment quantities are set by solving a network flow subproblem. Extensive computational experiments have been performed on benchmark instances from the literature. The results show that our algorithm generally outperforms existing heuristics for the PRP and can produce high-quality solutions in short computin...

GEDAR: Geographic and opportunistic routing protocol with Depth Adjustment for mobile underwater sensor networks

Abstract: Efficient protocols for data packet delivery in mobile underwater sensor networks (UWSNs) are crucial to the effective use of this new powerful technology for monitoring lakes, rivers, seas, and oceans. However, communication in UWSNs is a challenging task because of the characteristics of the acoustic channel. In this work, we present a feasible solution for improving the data packet delivery ratio in mobile UWSN. The GEographic and opportunistic routing with Depth Adjustment-based topology control for communication Recovery (GEDAR) over void regions uses the greedy opportunistic forwarding to route packets and to move void nodes to new depths to adjust the topology. Simulation results shown that GEDAR outperforms the baseline solutions in terms of packet delivery ratio, latency and energy per message.

Routing protocols for wireless sensor networks with mobile sinks: a survey

Abstract: Wireless sensor networks with mobile sinks, mWSNs, have attracted a lot of attention recently. This is because sink mobility can greatly alleviate the hotspot issue in WSNs and further prolong the network lifetime. However, sink mobility also causes unexpected changes in network topology and data routing paths, which can largely affect the routing performance in such networks. Design of efficient routing protocols for mWSNs has been a critical issue, and much work has been carried out in this aspect. In this article, we first classify existing protocols based on different design criteria and then present a survey of the state-of-the-art routing protocols in this area. We illustrate how each of the protocols works, and discuss their advantages and disadvantages. Finally, we point out some future directions for efficient routing in mWSNs.

R3E: Reliable Reactive Routing Enhancement for Wireless Sensor Networks

Abstract: Providing reliable and efficient communication under fading channels is one of the major technical challenges in wireless sensor networks (WSNs), especially in industrial WSNs (IWSNs) with dynamic and harsh environments. In this work, we present the Reliable Reactive Routing Enhancement (R3E) to increase the resilience to link dynamics for WSNs/IWSNs. R3E is designed to enhance existing reactive routing protocols to provide reliable and energy-efficient packet delivery against the unreliable wireless links by utilizing the local path diversity. Specifically, we introduce a biased backoff scheme during the route-discovery phase to find a robust guide path, which can provide more cooperative forwarding opportunities. Along this guide path, data packets are greedily progressed toward the destination through nodes' cooperation without utilizing the location information. Through extensive simulations, we demonstrate that compared to other protocols, R3E remarkably improves the packet delivery ratio, while maintaining high energy efficiency and low delivery latency.

Opportunistic Routing in Low Duty-Cycle Wireless Sensor Networks

Abstract: Opportunistic routing is widely known to have substantially better performance than unicast routing in wireless networks with lossy links. However, wireless sensor networks are usually duty cycled, that is, they frequently enter sleep states to ensure long network lifetime. This renders existing opportunistic routing schemes impractical, as they assume that nodes are always awake and can overhear other transmissions. In this article we introduce ORW, a practical opportunistic routing scheme for wireless sensor networks. ORW uses a novel opportunistic routing metric, EDC, that reflects the expected number of duty-cycled wakeups that are required to successfully deliver a packet from source to destination. We devise distributed algorithms that find the EDC-optimal forwarding and demonstrate using analytical performance models and simulations that EDC-based opportunistic routing results in significantly reduced delay and improved energy efficiency compared to traditional unicast routing. In addition, we evaluate the performance of ORW in both simulations and testbed-based experiments. Our results show that ORW reduces radio duty cycles on average by 50p (up to 90p on individual nodes) and delays by 30p to 90p when compared to the state-of-the-art.

TSRF: A Trust-Aware Secure Routing Framework in Wireless Sensor Networks

Abstract: In recent years, trust-aware routing protocol plays a vital role in security of wireless sensor networks (WSNs), which is one of the most popular network technologies for smart city. However, several key issues in conventional trust-aware routing protocols still remain to be solved, such as the compatibility of trust metric with QoS metrics and the control of overhead produced by trust evaluation procedure. This paper proposes a trust-aware secure routing framework (TSRF) with the characteristics of lightweight and high ability to resist various attacks. To meet the security requirements of routing protocols in WSNs, we first analyze features of common attacks on trust-aware routing schemes. Then, specific trust computation and trust derivation schemes are proposed based on analysis results. Finally, our design uses the combination of trust metric and QoS metrics as routing metrics to present an optimized routing algorithm. We show with the help of simulations that TSRF can achieve both intended security and high efficiency suitable for WSN-based networks.

A Spectrum-Aware Clustering for Efficient Multimedia Routing in Cognitive Radio Sensor Networks

Abstract: Multimedia applications are characterized as delay-sensitive and high-bandwidth stipulating traffic sources. Supporting such demanding applications on cognitive radio sensor networks (CRSNs) with energy and spectrum constraints is a highly daunting task. In this paper, we propose a spectrum-aware cluster-based energy-efficient multimedia (SCEEM) routing protocol for CRSNs that jointly overcomes the formidable limitations of energy and spectrum. Clustering is exploited to support the quality of service (QoS) and energy-efficient routing by limiting the participating nodes in route establishment. In SCEEM routing, the number of clusters is optimally determined to minimize the distortion in multimedia quality that occurs due to packet losses and latency. Moreover, the cluster-head selection is based on the energy and relative spectrum awareness such that noncontiguous available spectrum bands are clustered and scheduled to provide continuous transmission opportunity. Routing employs clustering with hybrid medium access by combining carrier-sense multiple access (CSMA) and time-division multiple access (TDMA). TDMA operates for intracluster transmission, whereas CSMA is used for intercluster routing. Thus, a cross-layer design of routing, i.e., of medium access control (MAC) and physical layers, provides efficient multimedia routing in CRSNs, which is revealed through simulation experiments.

TLR: A Traffic-Light-Based Intelligent Routing Strategy for NGEO Satellite IP Networks

Abstract: We present TLR, a traffic-light-based intelligent routing strategy for NGEO satellite IP networks. In TLR, a set of traffic lights are used to indicate the congestion status at both the current node and the next node. When a packet travels along a pre-calculated route to the destination, it may adjust the route dynamically, according to the real-time color of traffic lights at each intermediate node. Through the combination of preliminary planning and real-time adjustment, each packet can eventually get an approximately optimal transmission path. The multi-path routing mechanism in TLR can help achieve a good distribution of traffics when the network traffic increases. The Public Waiting Queue scheme in TLR can fully utilize free spaces of the buffer queues and lower the packet drop rate. While the concept of TLR has many advantages, it may result in endless-loop of routing. To eliminate this phenomenon, a defense scheme is incorporated in the design of TLR. A set of simulations are conducted using the Network Simulator (version 2) to verify the good performance of TLR, in terms of lower packet drop rate, better distribution of traffics and higher throughput, over the entire satellite constellation.

On the role of routing in named data networking

Abstract: A unique feature of Named Data Networking (NDN) is that its forwarding plane can detect and recover from network faults on its own, enabling each NDN router to handle network failures locally without relying on global routing convergence This new feature prompts us to re-examine the role of routing in an NDN network: does it still need a routing protocol? If so, what impact may an intelligent forwarding plane have on the design and operation of NDN routing protocols? Through analysis and extensive simulations, we show that routing protocols remain highly beneficial in an NDN network Routing disseminates initial topology and policy information as well as long-term changes in them, and computes the routing table to guide the forwarding process However, because the forwarding plane is capable of detecting and recovering from failures quickly, routing no longer needs to handle short-term churns in the network Freeing routing protocols from short-term churns can greatly improve their scalability and stability, enabling NDN to use routing protocols that were previously viewed as unsuitable for real networks

Segment routing extension headers

Abstract: A system and method are disclosed for using segment routing (SR) in native IP networks. The method involves receiving a packet. The packet is an IP packet and includes an IP header. The method also involves updating the packet. Updating the packet involves writing information, including a segment routing segment identifier, to the destination address of the packet.

Opportunistic Routing for Smart Grid With Power Line Communication Access Networks

Abstract: Power line communications (PLCs) have recently absorbed interest in the smart grid since they offer communication capability in an easy and simple deployment. The main role of PLC access network (PLC-AN), which is constructed with medium and low voltage distribution networks, is to exchange control signals between substations and end users or to provide the Internet access to homes. Since a transmission signal of narrowband PLC penetrates electronic devices, a use of opportunistic routing (OR) can be a viable option in PLC-AN design. In this paper, we investigate the feasibility of OR use in PLC-AN and propose a customized OR for it, named PLC-OR, which uses static geographical information. For doing this, we formulate a bit-meter per second maximization problem and solves it in a distributed manner. Through simulations, we confirm that our proposed PLC-OR successfully reduces packet transmission time compared to the traditional sequential routing while achieving the same level of reliability in packet delivery.

Throughput-Aware Routing for Industrial Sensor Networks: Application to ISA100.11a

Abstract: This paper proposes a routing algorithm that enhances throughput and decreases end-to-end delay in industrial cognitive radio sensor networks (ICRSNs) based on ISA100.11a. In ICRSNs, the throughput is downgraded by interference from primary networks. The proposed routing algorithm is targeted at large-scale networks where data are forwarded through different clusters on their way to the sink. By estimating the maximum throughput for each path, the data can be forwarded through the most optimal path. Simulation results show that our scheme can enhance throughput and decrease end-to-end delay.

Hypercube-Based Multipath Social Feature Routing in Human Contact Networks

Abstract: Most routing protocols for delay tolerant networks resort to the sufficient state information, including trajectory and contact information, to ensure routing efficiency. However, state information tends to be dynamic and hard to obtain without a global and/or long-term collection process. In this paper, we use the internal social features of each node in the network to perform the routing process. In this way, feature-based routing converts a routing problem in a highly mobile and unstructured contact space to a static and structured feature space. This approach is motivated from several human contact networks, such as the Infocom 2006 trace and MIT reality mining data, where people contact each other more frequently if they have more social features in common. Our approach includes two unique processes: social feature extraction and multipath routing. In social feature extraction, we use entropy to extract the m most informative social features to create a feature space (F-space): (F1, F2,..., Fm), where Fi corresponds to a feature. The routing method then becomes a hypercube-based feature matching process, where the routing process is a step-by-step feature difference resolving process. We offer two special multipath routing schemes: node-disjoint-based routing and delegation-based routing. Extensive simulations on both real and synthetic traces are conducted in comparison with several existing approaches, including spray-and-wait routing, spray-and-focus routing, and social-aware routing based on betweenness centrality and similarity. In addition, the effectiveness of multipath routing is evaluated and compared to that of single-path routing.

Traffic steering in software defined networks: planning and online routing

Abstract: Middleboxes have become ubiquitous in data center as well as wide area networks Simple routing of flows from ingress to egress along shortest paths has been replaced by policy aware paths that have to pass through the required set of middleboxes The complex routing is one of the major impetus for the Software Defined Networking (SDN) paradigm In this paper, we consider both offline planning and online routing problems in SDN framework The offline planning problem is one where aggregate demands are specified and the objective is to determine whether there is enough capacity in the network to handle the demands We develop a fast FPTAS for the problem based on segmentation and lazy dual update In the online routing problem, flow requests are given one at a time and the objective is to steer the flows to maximize the total amount of traffic accepted over time We develop a log-competitive algorithm based on time-dependent duals

A secure multi-hop routing for IoT communication

Abstract: This paper introduces a multi-hop routing protocol that enables secured IoT devices' communication. The routing protocol enables the IoT devices to authenticate before forming a new network or joining an existing network. The authentication uses multi-layer parameters to enhance the security of the communication. The proposed routing protocol embeds the multi-layer parameters into the routing algorithm, thus combining the authentication and routing processes without incurring significant overheads. The multi-layer parameters include a unique User-Controllable Identification, users' pre-agreed application(s), and a list of permitted devices, thus saving resources by maintaining smaller routing information. Experimental and field tests were conducted with results showing that our secure multi-hop routing is suitable to be deployed for IoT communication.

Keep Forwarding: Towards K-link Failure Resilient Routing

Abstract: Handling link failures is the fundamental task of routing schemes. Routing protocols based on link state (e.g., OSPF) require a global state advertisement and re-computation when link failure happens, and will cause inevitable delivery failures. To improve the routing resilience without introducing significant extra overhead, we propose a new routing approach, Keep Forwarding (KF) to achieve k-link failure resilience using inport-aware forwarding. KF is (i) flexible to handle multiple failures (or k-failure) with only small path stretch, (ii) efficient in recovery speed by instant and local lookup, (iii) bounded on memory requirement. Besides, the proposed approach is compatible with existing Internet protocols and routing infrastructures (e.g., requires no packet labeling or state recording), and the pre-computation has a linear temporal complexity. Experimental results on real ISP and datacenter networks reveal that KF guarantees near-optimal resilience (99.9%∼100% for single failure and over 99.7% for multiple failures), with the average path stretch increment less than 5%.

Adaptive and Secure Load-Balancing Routing Protocol for Service-Oriented Wireless Sensor Networks

Abstract: Service-oriented architectures for wireless sensor networks (WSNs) have been proposed to provide an integrated platform, where new applications can be rapidly developed through flexible service composition. In WSNs, the existing multipath routing schemes have demonstrated the effectiveness of traffic distribution over multipaths to fulfill the quality of service requirements of applications. However, the failure of links might significantly affect the transmission performance, scalability, reliability, and security of WSNs. Thus, by considering the reliability, congestion control, and security for multipath, it is desirable to design a reliable and service-driven routing scheme to provide efficient and failure-tolerant routing scheme. In this paper, an evaluation metric, path vacant ratio, is proposed to evaluate and then find a set of link-disjoint paths from all available paths. A congestion control and load-balancing algorithm that can adaptively adjust the load over multipaths is proposed. A threshold sharing algorithm is applied to split the packets into multiple segments that will be delivered via multipaths to the destination depending on the path vacant ratio. Simulations demonstrate the performance of the adaptive and secure load-balance routing scheme. © 2014 IEEE.

Relative Distance Based Forwarding Protocol for Underwater Wireless Networks

Abstract: Underwater wireless sensor network (UWSN) features many unique characteristics, including slow propagation speed, high end-to-end delay, low available bandwidth, variable link quality, and energy constraint. All these problems pose a big challenge to devise a transmission efficient, energy-saving, and low delay routing protocol for UWSNs. In this paper we devise a relative distance based forwarding (RDBF) routing protocol, which aims to provide transmission efficient, energy-saving, and low delay routing. We utilize a fitness factor to measure and judge the degree of appropriateness for a node to forward the packets. Under the limitations of the fitness factor, RDBF can confine the scope of the candidate forwarders and find the beneficial relays to forward packets. In this way, only a small fraction of nodes are involved in forwarding process, which can distinctly reduce the energy consumption. Moreover, using only the selected beneficial nodes as forwarders can both enhance the transmission efficiency and reduce the end-to-end delay. This is because the distances of these nodes to the sink are the shortest and the hop counts of routing paths consisted by these nodes are minimum. We use the ns-2 based simulator to conduct our experiment; the results show that RDBF performs better in terms of packet delivery ratio, end-to-end delay, and energy efficiency.

Path-Congestion-Aware Adaptive Routing With a Contention Prediction Scheme for Network-on-Chip Systems

Abstract: Network-on-chip systems can achieve higher performance than bus systems for chip multiprocessor systems. However, as the complexity of the network increases, the channel and switch congestion problems become major performance bottlenecks. An effective adaptive routing algorithm can help minimize path congestion through load balancing. However, conventional adaptive routing schemes only use channel-based information to detect the congestion status. Due to the lack of switch-based information, channel-based information is difficult to reveal the real congestion status along the routing path. Therefore, in this paper, we remodel the path congestion information to show hidden spatial congestion information and improve the effectiveness of routing path selection. We propose a path-congestion-aware adaptive routing (PCAR) scheme based on the following techniques: 1) a path-congestion-aware selection strategy that simultaneously considers switch congestion and channel congestion, and 2) a contention prediction technique that uses the rate of change in the buffer level to predict possible switch contention. The experimental results show that the proposed PCAR scheme can achieve a high saturation throughput with an improvement of 15.4%-48.7% compared to existing routing schemes. The proposed PCAR method also includes a VLSI architecture, which has higher area efficiency with an improvement of 16%-35.7% compared with the other router designs.

Neighbor Table Based Shortcut Tree Routing in ZigBee Wireless Networks

Abstract: The ZigBee tree routing is widely used in many resource-limited devices and applications, since it does not require any routing table and route discovery overhead to send a packet to the destination. However, the ZigBee tree routing has the fundamental limitation that a packet follows the tree topology; thus, it cannot provide the optimal routing path. In this paper, we propose the shortcut tree routing (STR) protocol that provides the near optimal routing path as well as maintains the advantages of the ZigBee tree routing such as no route discovery overhead and low memory consumption. The main idea of the shortcut tree routing is to calculate remaining hops from an arbitrary source to the destination using the hierarchical addressing scheme in ZigBee, and each source or intermediate node forwards a packet to the neighbor node with the smallest remaining hops in its neighbor table. The shortcut tree routing is fully distributed and compatible with ZigBee standard in that it only utilizes addressing scheme and neighbor table without any changes of the specification. The mathematical analysis proves that the 1-hop neighbor information improves overall network performances by providing an efficient routing path and distributing the traffic load concentrated on the tree links. In the performance evaluation, we show that the shortcut tree routing achieves the comparable performance to AODV with limited overhead of neighbor table maintenance as well as overwhelms the ZigBee tree routing in all the network conditions such as network density, network configurations, traffic type, and the network traffic.

Sweet Little Lies: Fake Topologies for Flexible Routing

Abstract: Link-state routing protocols (e.g., OSPF and IS-IS) are widely used because they are scalable, robust, and based on simple abstractions. Unfortunately, these protocols are also relatively inflexible, since they direct all traffic over shortest paths. In contrast, Software Defined Networking (SDN) offers fine-grained control over routing, at the expense of controller overhead, failover latency, and deployment challenges.We argue that future networks can achieve the benefits of both approaches through central control over the distributed route computation. The key idea, which we call Fibbing, is to have the controller trick the routers into seeing a fake topology that is carefully constructed to achieve the desired Forwarding Information Base (FIB). Given an acyclic forwarding graph for each destination, the controller computes an augmented topology with fake nodes (and destinations to announce there) and fake links (and link weights). The controller injects these "lies" into the link-state routing protocol, and the routers simply compute the paths accordingly. The controller can also select an augmented topology that triggers the use of specific backup paths when real links and routers fail. To reduce router load, our Fibbing algorithms compute augmented topologies of minimal size. Our preliminary evaluation on realistic ISP topologies shows that Fibbing works well in practice.

Presence-based communication routing service and regulation of same

Abstract: Systems, methods, and user interfaces are provided for customized communication routing and regulation thereof. The routing of an incoming communication to a device, wireless or wireline, is based on a routing preference and a presence condition of a mobile device in a home or visited wireless environment served by a confined-coverage access point (AP). The routing preference can be configured for a device that operates in the home or visited wireless environment. The confined-coverage AP can be owned or leased by a subscriber associated with the incoming call or by a third party. Provisioning of routing of incoming call based on a third-party confined-coverage AP can be event-based. Add-on services can be provisioned and configured; screening of incoming call(s) based on screening rule(s) specific to an confined-coverage AP is provided. Customized communication routing to equipment that operates in a confined-coverage area served by a third-party confined-coverage AP can be cancelled.

Too Many SDN Rules? Compress Them with MINNIE

Abstract: Software Defined Networking (SDN) is gaining momentum with the support of major manufacturers. While it brings flexibility in the management of flows within the data center fabric, this flexibility comes at the cost of smaller routing table capacities. In this paper, we investigate compression techniques to reduce the forwarding information base (FIB) of SDN switches. We validate our algorithm, called MINNIE, on a real testbed able to emulate a 20 switches fat tree architecture. We demonstrate that even with a small number of clients, the limit in terms of number of rules is reached if no compression is performed, increasing the delay of all new incoming flows. MINNIE, on the other hand, reduces drastically the number of rules that need to be stored with a limited impact on the packet loss rate. We also evaluate the actual switching and reconfiguration times and the delay introduced by the communications with the controller.

Cross-Layer Aided Energy-Efficient Opportunistic Routing in Ad Hoc Networks

Abstract: Most of the nodes in ad hoc networks rely on batteries, which requires energy saving. Hence, numerous energy-efficient routing algorithms have been proposed for solving this problem. In this paper, we exploit the benefits of cross-layer information exchange, such as the knowledge of the Frame Error Rate (FER) in the physical layer, the maximum number of retransmissions in the Medium Access Control (MAC) layer and the number of relays in the network layer. Energy-consumption-based Objective Functions (OF) are invoked for calculating the end-to-end energy consumption of each potentially available route for both Traditional Routing (TR) and for our novel Opportunistic Routing (OR), respectively. We also improve the TR and the OR with the aid of efficient Power Allocation (PA) for further reducing the energy consumption. For the TR, we take into account the dependencies amongst the links of a multi-hop route, which facilitates a more accurate performance evaluation than upon assuming the links that are independent. Moreover, two energy-efficient routing algorithms are designed based on Dijkstra's algorithm. The algorithms based on the energy OF provide the theoretical bounds, which are shown to be close to the bound found from exhaustive search, despite the significantly reduced complexity of the former. Finally, the end-to-end throughput and the end-to-end delay of this system are analyzed theoretically and a new technique of characterizing the delay distribution of OR is proposed. The simulation results show that our energy-efficient OR outperforms the TR and that their theoretical analysis accurately matches the simulation results.

Load balancing for multiple traffic matrices using SDN hybrid routing

Abstract: Classical traffic engineering (TE) methods calculate the optimal routing based on a single traffic matrix. However, they are unable to handle unexpected traffic changes. Thus, it is of interest to find a good routing configuration to accommodate multiple possible traffic scenarios. There are two major approaches to achieve load balancing for multiple traffic matrices: destination-based routing and explicit routing. It has been shown that explicit routing performs better than destination-based routing for multiple traffic matrices. However, explicit routing has high complexity and requires large Ternary Content Addressable Memory (TCAM) in the routers. Thus, it is power hungry and unscalable. This paper presents an approach called hybrid routing to achieve load balancing for multiple traffic matrices with low complexity and good scalability. Our basic idea is to complement destination-based routing with a small number of explicit routing forwarding entries to take advantage of both two routing approaches. Hybrid routing greatly reduces the number of forwarding entries compared with pure explicit routing. This has great value for practice in that the scheme requires very small TCAM to implement. Hybrid routing is very suitable for implementation using SDN. A heuristic algorithm is developed to obtain the near-optimal hybrid routing configuration. Extensive evaluation demonstrates the effectiveness of hybrid routing. The results show that hybrid routing achieves near-optimal load balancing compared with pure explicit routing. In particular, hybrid routing saves at least 84.6% TCAM resources in all practical networks used in our evaluation.

Accurate prediction of detailed routing congestion using supervised data learning

Abstract: Routing congestion model is of great importance in design stages of modern physical synthesis, e.g. global routing and routability estimation during placement. As the technology node becomes smaller, routing congestion is more difficult to estimate during design stages ahead of detailed routing. In this paper, we propose a framework using nonparametric regression technique in machine learning to construct routing congestion model. The constructed model can capture multiple factors and enables direct prediction of detailed routing congestion with high accuracy. By using this model in global routing, significant reduction of design rule violations and detailed routing runtime can be achieved compared with the model in previous work, with small overhead in global routing runtime and memory usage.

Congestion Aware Routing in Nonlinear Elastic Optical Networks

Abstract: In elastic optical networks, digital coherent transceivers modify their symbol rate, modulation format, and forward error correction to best serve the network demands. In a nonlinear elastic optical network, these parameters are inherently coupled with the routing algorithm. We propose to use congestion aware routing in a nonlinear elastic optical network and demonstrate its efficacy for the NSFNET reference network (14 nodes, 22 links). The network is sequentially loaded with 100 GbE demands until a demand becomes blocked, this procedure being repeated 10000 times to estimate the network blocking probability (NBP). Three routing algorithms are considered: 1) shortest path routing; 2) simple congestion aware algorithm; and 3) weighted congestion aware routing algorithm with 50, 25, 12.5, and 6.25 GHz resolution flexgrids. For NBP = 1% using a 50 GHz grid, congestion aware routing doubles the network capacity compared with the shortest path routing. When congestion aware routing is combined with a 6.25 GHz resolution flexgrid, a fivefold increase in network capacity is afforded.

An optimization of the object function for routing protocol of low-power and Lossy networks

Abstract: Routing Protocol for Low-Power and Lossy Networks (RPL) is the Internet Engineering Task Force (IETF) standard for IPv6 routing in Low-power and Lossy Networks (LLNs). By using the Objective Function (OF) and a collection of routing metrics, it can build a Destination Oriented Directed Acyclic Graph (DODAG). There are two kinds of OFs specified by the IETF, Objective Function Zero (OF0) and Minimum Rank with Hysteresis Objective Function (MRHOF) respectively. The former is based on minimum hop count while the latter is based on Expected Transmission Count (ETX) and is more preferable. However, as the network size increases, both MRHOF and OF0 will introduce long single hop, which may become the routing bottleneck that restricts the entire network. In this paper, the problem is solved by optimizing the MRHOF with a new routing metric, the PER-HOP ETX. Instead of working with additive ETX metrics along a route, PER-HOP ETX distributes the ETX value to each node along the route. This method can achieve better routing performance in large-scale sensor network scenario. A detailed mathematical proof is given in the paper, and simulations were carried out based on the Contiki operating system. Experiments showed that PER-HOP ETX, the proposed optimization outperforms OF0 and ETX in terms of network latency, packet delivery ratio and energy consumption when the network scale becomes large.