Evaluation of RPL’s Single Metric Objective Functions

In this paper, we evaluate the performance of RPL (IPv6 Routing Protocol for Low Power and Lossy Networks) based on the Objective Function being used to construct the Destination Oriented Directed Acyclic Graph (DODAG). Using the Cooja simulator, we compared Objective Function Zero (OF0) with the Minimum Rank with Hysteresis Objective Function (MRHOF) in terms of average power consumption, packet loss ratio, and average end-to-end latency. Our study shows that RPL performs better in terms of packet loss ratio and average endto-end latency when MRHOF is used as an objective function. However, the average power consumption is noticeably higher compared to OF0

Towards Efficient Load Balancing Strategy for RPL Routing Protocol in IoT Networks

학위논문 (석사)-- 서울대학교 대학원 : 공과대학 컴퓨터공학부, 2018. 8. Chong-Kwon Kim.The IPv6 Routing Protocol for Low-Power and Lossy Networks (RPL) has been considered as the new standard routing protocol designed to meet the requirements of wide range of Low Power and Lossy Networks (LLNs) applications including industrial and environmental monitoring, smart grid, and wireless sensor networks. However, due to the uneven deployment of sensor nodes in large-scale networks and the heterogeneous traffic patterns, some sensor nodes have much heavier workload than others. The lack of load balancing mechanism results in these sensor nodes quickly exhausting their energy, therefore shorten the network lifetime of battery-powered wireless sensor networks. To overcome this problem, we propose a skewness and load balancing routing protocol based on the RPL protocol, named SB-RPL that exploits various routing metrics including link quality and skewness among subtrees of the network in support topology construction. In this work, we first investigate the load balancing and related issues of RPL both via numerical simulations and via actual large-scale testbed. Performance analysis results show that RPL trees suffer from severe skewness regardless of routing metrics in randomly generated networks. Through extensive computer simulations and actual experiments, we demonstrate that SB-RPL significantly improves end-to-end packet delivery performance and tree balance compared to the standard RPL.Contents ABSTRACT…………………………………………………………..i Contents…………………………………………………………….iii List of Figures...……………………………………………………vi List of Tables…...…………………………………………………vii Glossary…………..…………………………………………………viii Chapter I: Introduction ................................................. 1 1.1. Overview ............................................................... 1 1.2. Motivation ............................................................. 2 1.3. Key Idea ................................................................. 4 1.4. Contribution ........................................................... 4 1.5. Thesis Organization ................................................. 6 Chapter II: Background and Literature Review ................. 7 2.1. RPL Overview .......................................................... 7 2.2. DODAG Construction ............................................... 7 2.3. Trickle Timer .............................................................10 2.4. RPL Operation Modes ...............................................11 2.5. Literature Review ......................................................11 2.5.1. RPL Objective Functions: ........................................11 2.5.2. Balanced Routing protocols ...................................13 Chapter III: System Modeling .......................................... 15 3.1. System Models .........................................................15 3.2. RPL Objective Function: ............................................17 Chapter IV: SB-RPL Design .............................................. 20 4.1. Topology-Aware Node Influence ...............................20 4.2. RPL Control Message DIO extension in support of balancing routing .............................................................20 4.3. SB-RPL Design ...........................................................21 Chapter V: Evaluation ...................................................... 25 5.1. RPL in Contiki OS .......................................................25 5.2. Methodology .............................................................26 5.2.1. Testbed Experiments: ..............................................26 5.3. Compared Objective Functions ...................................28 5.4. Metrics........................................................................29 5.5. Testbed Experiments....................................................30 5.5.1. Impact of α and β: ....................................................30 5.5.2. Objective Function Comparison ...............................36 5.6. Cooja-based Simulations ............................................38 5.6.1. Impact of Network Scales ........................................40 5.6.2. Impact of Network Density ......................................41 Chapter VI: Conclusion ..................................................... 43 Bibliography ..................................................................... 44 요 약.................................................................................. 50 Acknowledgments ............................................................ 52Maste

Performance Assessment of Routing Protocols for IoT/6LoWPAN Networks

The Internet of Things (IoT) proposes a disruptive communication paradigm that allows smart objects to exchange data among themselves to reach a common goal. IoT application scenarios are multiple and can range from a simple smart home lighting system to fully controlled automated manufacturing chains. In the majority of IoT deployments, things are equipped with small devices that can suffer from severe hardware and energy restrictions that are responsible for performing data processing and wireless communication tasks. Thus, due to their features, communication networks that are used by these devices are generally categorized as Low Power and Lossy Networks (LLNs). The considerable variation in IoT applications represents a critical issue to LLN networks, which should offer support to different requirements as well as keeping reasonable quality-of-service (QoS) levels. Based on this challenge, routing protocols represent a key issue in IoT scenarios deployment. Routing protocols are responsible for creating paths among devices and their interactions. Hence, network performance and features are highly dependent on protocol behavior. Also, based on the adopted protocol, the support for some specific requirements of IoT applications may or may not be provided. Thus, a routing protocol should be projected to attend the needs of the applications considering the limitations of the device that will execute them. Looking to attend the demand of routing protocols for LLNs and, consequently, for IoT networks, the Internet Engineering Task Force (IETF) has designed and standardized the IPv6 Routing Protocol for Low Power and Lossy Networks (RPL). This protocol, although being robust and offering features to fulfill the need of several applications, still presents several faults and weaknesses (mainly related to its high complexity and memory requirement), which limits its adoption in IoT scenarios. An alternative to RPL, the Lightweight On-demand Ad Hoc Distancevector Routing Protocol – Next Generation (LOADng) has emerged as a less complicated routing solution for LLNs. However, the cost of its simplicity is paid for with the absence of adequate support for a critical set of features required for many IoT environments. Thus, based on the challenging open issues related to routing in IoT networks, this thesis aims to study and propose contributions to better attend the network requirements of IoT scenarios. A comprehensive survey, reviewing state-of-the-art routing protocols adopted for IoT, identified the strengths and weaknesses of current solutions available in the literature. Based on the identified limitations, a set of improvements is designed to overcome these issues and enhance IoT network performance. The novel solutions are proposed to include reliable and efficient support to attend the needs of IoT applications, such as mobility, heterogeneity, and different traffic patterns. Moreover, mechanisms to improve the network performance in IoT scenarios, which integrate devices with different communication technologies, are introduced. The studies conducted to assess the performance of the proposed solutions showed the high potential of the proposed solutions. When the approaches presented in this thesis were compared with others available in the literature, they presented very promising results considering the metrics related to the Quality of Service (QoS), network and energy efficiency, and memory usage as well as adding new features to the base protocols. Hence, it is believed that the proposed improvements contribute to the state-of-the-art of routing solutions for IoT networks, increasing the performance and adoption of enhanced protocols.A Internet das Coisas, do inglês Internet of Things (IoT), propõe um paradigma de comunicação disruptivo para possibilitar que dispositivos, que podem ser dotados de comportamentos autónomos ou inteligentes, troquem dados entre eles buscando alcançar um objetivo comum. Os cenários de aplicação do IoT são muito variados e podem abranger desde um simples sistema de iluminação para casa até o controle total de uma linha de produção industrial. Na maioria das instalações IoT, as “coisas” são equipadas com um pequeno dispositivo, responsável por realizar as tarefas de comunicação e processamento de dados, que pode sofrer com severas restrições de hardware e energia. Assim, devido às suas características, a rede de comunicação criada por esses dispositivos é geralmente categorizada como uma Low Power and Lossy Network (LLN). A grande variedade de cenários IoT representam uma questão crucial para as LLNs, que devem oferecer suporte aos diferentes requisitos das aplicações, além de manter níveis de qualidade de serviço, do inglês Quality of Service (QoS), adequados. Baseado neste desafio, os protocolos de encaminhamento constituem um aspecto chave na implementação de cenários IoT. Os protocolos de encaminhamento são responsáveis por criar os caminhos entre os dispositivos e permitir suas interações. Assim, o desempenho e as características da rede são altamente dependentes do comportamento destes protocolos. Adicionalmente, com base no protocolo adotado, o suporte a alguns requisitos específicos das aplicações de IoT podem ou não ser fornecidos. Portanto, estes protocolos devem ser projetados para atender as necessidades das aplicações assim como considerando as limitações do hardware no qual serão executados. Procurando atender às necessidades dos protocolos de encaminhamento em LLNs e, consequentemente, das redes IoT, a Internet Engineering Task Force (IETF) desenvolveu e padronizou o IPv6 Routing Protocol for Low Power and Lossy Networks (RPL). O protocolo, embora seja robusto e ofereça recursos para atender às necessidades de diferentes aplicações, apresenta algumas falhas e fraquezas (principalmente relacionadas com a sua alta complexidade e necessidade de memória) que limitam sua adoção em cenários IoT. Em alternativa ao RPL, o Lightweight On-demand Ad hoc Distance-vector Routing Protocol – Next Generation (LOADng) emergiu como uma solução de encaminhamento menos complexa para as LLNs. Contudo, o preço da simplicidade é pago com a falta de suporte adequado para um conjunto de recursos essenciais necessários em muitos ambientes IoT. Assim, inspirado pelas desafiadoras questões ainda em aberto relacionadas com o encaminhamento em redes IoT, esta tese tem como objetivo estudar e propor contribuições para melhor atender os requisitos de rede em cenários IoT. Uma profunda e abrangente revisão do estado da arte sobre os protocolos de encaminhamento adotados em IoT identificou os pontos fortes e limitações das soluções atuais. Com base nas debilidades encontradas, um conjunto de soluções de melhoria é proposto para superar carências existentes e melhorar o desempenho das redes IoT. As novas soluções são propostas para incluir um suporte confiável e eficiente capaz atender às necessidades das aplicações IoT relacionadas com suporte à mobilidade, heterogeneidade dos dispositivos e diferentes padrões de tráfego. Além disso, são introduzidos mecanismos para melhorar o desempenho da rede em cenários IoT que integram dispositivos com diferentes tecnologias de comunicação. Os vários estudos realizados para mensurar o desempenho das soluções propostas mostraram o grande potencial do conjunto de melhorias introduzidas. Quando comparadas com outras abordagens existentes na literatura, as soluções propostas nesta tese demonstraram um aumento do desempenho consistente para métricas relacionadas a qualidade de serviço, uso de memória, eficiência energética e de rede, além de adicionar novas funcionalidades aos protocolos base. Portanto, acredita-se que as melhorias propostas contribuiem para o avanço do estado da arte em soluções de encaminhamento para redes IoT e aumentar a adoção e utilização dos protocolos estudados

A New Objective Function Based on Additive Combination of Node and Link Metrics as a Mechanism Path Selection for RPL Protocol

Since its development by IETF, the IPv6 routing protocol for low power and lossy networks (RPL) remains the subject of several researches. RPL is based on objective function as a mechanism selection of paths in the network. However, the default objective functions standardized selects the routes according to a single routing metric that leads to an unoptimized path selection and a lot of parent changes. Thus, we propose in this paper weighted combined metrics objective function (WCM-OF) and non-weighted combined metrics objective function (NWCM-OF) that are based both on additive link quality and energy metrics with equal weights or not to achieve a tradeoff between reliability and saved energy levels. The proposed objective functions were implemented in the core of Contiki operating system and evaluated with Cooja emulator. Results show that the proposed objective functions improved the network performances compared to default objective functions

A hybrid objective function with empirical stability aware to improve RPL for IoT applications

The diverse applications of the internet of things (IoT) require adaptable routing protocol able to cope with several constraints. Thus, RPL protocol was designed to meet the needs for IoT networks categorized as low power and lossy networks (LLN). RPL uses an objective function based on specific metrics for preferred parents selection through these packets are sent to root. The single routing metric issue generally doesn’t satisfy all routing performance requirements, whereas some are improved others are degraded. In that purpose, we propose a hybrid objective function with empirical stability aware (HOFESA), implemented in the network layer of the embedded operating system CONTIKI, which combines linearly three weighty metrics namely hop count, RSSI and node energy consumption. Also, To remedy to frequent preferred parents changes problems caused by taking into account more than one metric, our proposal relies on static and empirical thresholds. The designed HOFESA, evaluated under COOJA emulator against Standard-RPL and EC-OF, showed a packet delivery ratio improvement, a decrease in the power consumption, the convergence time and DIO control messages as well as it gives network stability through an adequate churn

A context-aware tool-set for routing-targeted mutual configuration and optimization of LLNs through bridging virtual and physical worlds

International audienceIn the history of the WSN, unexpected routing behaviors is always a main issue of the large scale WSN deployments. Considering the high cost of building a real deployment, network simulators are often used in this domain. However, the original problem is still not solved although the era of IoT has been coming. A new concept of LLN is emerging. We realize that, no matter how wonderful the results from the simulation scenarios and thorough testing, the problems, such as bad performance or even severe system failures due to suboptimal routing path, would still happen in the real-world system. Our context-aware tool-set can help to build the simulation topology which is more close to the real network through mapping a serial routing metrics defined by IEFT ROLL working group and the link situation of the actual network. We believe our suggestion of bridging virtual and physical worlds reflected on our proposed tool-set could conduct more precise routing-targeted simulations. Moreover, by close-loop method, the knowledge and analyzed simulation results can lead us to improve the routing topology of the deployed LLN

A burst and congestion-aware routing metric for RPL protocol in IoT network

The packet loss and power consumption are the main issues considered once congestion occurs in any network, such as the Internet of Things (IoT) with a huge number of sensors and applications. Since IPv6 Routing Protocol for Low Power and Lossy Networks (RPL) is not initially designed for high stream traffic load, this restricts the application domain of RPL in several IoT scenarios such as burst traffic scenarios. The performance of RPL suffers in a network with burst traffic load, which leads to reducing the lifetime of the network and causing traffic congestion among the neighbour nodes. Therefore, to address this issue, we proposed a Burst and Congestion-Aware Metric for RPL called BCA-RPL, which calculates the rank, considering the number of packets. Also, the proposed mechanism includes congestion avoiding and load balancing techniques by switching the best parent selection to avoid the congested area. Our scheme is built and compared to the original RPL routing protocol for low power and lossy network with OF0 (OF0-RPL). Simulation results based on Cooja simulator shows BCA-RPL performs better than the original RPL-OF0 routing protocol in terms of packet loss, power consumption and packet delivery ratio (PDR) under burst traffic load. The BCA-RPL significantly improves the network where it decreases the packet loss around 50% and power consumption to an acceptable level with an improvement on the PDR of the IoT network

Comparative Analysis of Objective Functions in Routing Protocol for Low Power and Lossy Networks

Internet-of-Things (IoT), a new paradigm, has led to the extensive increase in communication among the tiny and embedded network devices. Majority of those devices are power, memory, and energy constrained and are made to work in lossy environments, thus forming an important part of Low Power and Lossy Networks (LLNs). Routing Protocol for Low Power and Lossy Networks (RPL) designed by Internet Engineering Task Force (IETF) is proved to be an effective candidate for routing in such networks. RPL defines the Objective Functions (OFs) in which a set of routing metrics (like hop count, ETX and so on) are used either in an individual or combined manner for optimal path selection between the nodes of the network in terms of various performance factors like power consumed, Packet Delivery Ratio (PDR), reliability and so on. There are two standard Objective Functions- Objective function Zero (OF0) and Minimum Rank Hysteresis Objective Function (MRHOF). The former uses the hop count and the latter uses the Expected Transmission Count (ETX) as the default routing metrics to select the optimal paths. But both of them are single metric Objective Functions (OFs) and have to face various issues regarding the energy consumed, network lifetime and so on. So a number of RPL optimizations incorporating the different routing metrics in a combined way have been proposed to enhance the performance in all respects. This paper gives the comparative analysis of existing Objective Functions that are based on different routing metrics and concludes that the use of a combination of multiple metrics will further improve the RPL performance in future