Segment Routing: a Comprehensive Survey of Research Activities, Standardization Efforts and Implementation Results

Fixed and mobile telecom operators, enterprise network operators and cloud providers strive to face the challenging demands coming from the evolution of IP networks (e.g. huge bandwidth requirements, integration of billions of devices and millions of services in the cloud). Proposed in the early 2010s, Segment Routing (SR) architecture helps face these challenging demands, and it is currently being adopted and deployed. SR architecture is based on the concept of source routing and has interesting scalability properties, as it dramatically reduces the amount of state information to be configured in the core nodes to support complex services. SR architecture was first implemented with the MPLS dataplane and then, quite recently, with the IPv6 dataplane (SRv6). IPv6 SR architecture (SRv6) has been extended from the simple steering of packets across nodes to a general network programming approach, making it very suitable for use cases such as Service Function Chaining and Network Function Virtualization. In this paper we present a tutorial and a comprehensive survey on SR technology, analyzing standardization efforts, patents, research activities and implementation results. We start with an introduction on the motivations for Segment Routing and an overview of its evolution and standardization. Then, we provide a tutorial on Segment Routing technology, with a focus on the novel SRv6 solution. We discuss the standardization efforts and the patents providing details on the most important documents and mentioning other ongoing activities. We then thoroughly analyze research activities according to a taxonomy. We have identified 8 main categories during our analysis of the current state of play: Monitoring, Traffic Engineering, Failure Recovery, Centrally Controlled Architectures, Path Encoding, Network Programming, Performance Evaluation and Miscellaneous...Comment: SUBMITTED TO IEEE COMMUNICATIONS SURVEYS & TUTORIAL

Fast reroute using segment routing for smart grids

Tese de mestrado, Engenharia Informática (Arquitectura, Sistemas e Redes de Computadores) Universidade de Lisboa, Faculdade de Ciências, 2016A rede eléctrica tem contribuído de forma extraordinária para o nosso dia-a-dia nas últimas décadas e, como tal, tornou-se essencial para a nossa sociedade. Hoje em dia, estão a ser tomadas decisões para a modernizar, de modo a que seja possível fornecer novos serviços. Graças ao aumento da produção¸ ão de electricidade através de energias renováveis (energia solar, hídrica e eólica), e ao aumento do consumo de energia, é vista como necessária uma reestruturação da rede eléctrica. Para atingir estes objectivos, foi proposta uma nova geração destas redes, as Smart Grids (SG). As SG são compostas por dispositivos electrónicos inteligentes, sensores com e sem fios e contadores inteligentes que necessitam de se coordenar para funcionarem correctamente. Como tal, é fundamental ter uma rede de comunicação moderna capaz de suportar estes desafios [1]. Um conjunto de propriedades de que se destacam a escalabilidade, disponibilidade e segurança, são fulcrais para o funcionamento das SG. Para as SG a infra-estrutura de comunicação tem um papel particularmente importante para que se possam cumprir estas necessidades. As tecnologias actuais baseadas em Internet Protocol (IP) e em Multiprotocol Layer Switching (MPLS) tˆem conseguido corresponder a estas necessidades. O protocolo IP é um dos alicerces para a comunicação mundial, enquanto que o MPLS tem sido adoptado pelas suas capacidades de engenharia de tráfego. No entanto, as redes de IP tradicionais são difíceis de gerir e tornam complicado o desenho de soluções que permitam utilização eficiente de recursos e que possibilitem comunicação resiliente. Por outro lado, o MPLS tem problemas de escalabilidade devido ao uso de protocolos complexos como o Resource Reservation Protocol with Traffic Engineering (RSVP-TE). As Software Defined Networks (SDN) promete resolver alguns dos problemas mencionados anteriormente, a partir do desacoplamento do plano de dados do plano de controlo, que passa a ser gerido por um controlador logicamente centralizado [2][3][4]. Deste modo, as aplicações que são executadas no controlador têm uma visão centralizada do estado da rede, o que facilita a procura de soluções de gestão de redes. No entanto, os operadores de SG poderão apresentar alguma relutância ao mover todos os seus elementos da rede para uma SDN. Felizmente, foi proposto recentemente um novo protocolo pela Internet Engineering Task Force (IETF) – Segment Routing (SR) [5] – que permite a centralização lógica oferecida por uma SDN num ambiente de uma rede MPLS. SR ´e muito semelhante ao MPLS, na medida em que utiliza segmentos que se comportam como etiquetas MPLS. A comutação de pacotes, baseada também nestas etiquetas, é gerida por comutadores que usam as mesmas acções do MPLS (push, pop e swap). No entanto, ao contrário do MPLS, o SR não necessita de protocolos complexos como o RSVP-TE, simplificando a gestão da rede. O SR utiliza uma forma de source routing, facilitadora da sua integração. Desta forma o SR pode ser integrado com os controladores SDN e outras aplicações. Para implementar SR, o controlador SDN apenas precisa de enviar uma lista ordenada de segmentos para o encaminhador que a insere no cabeçalho dos pacotes quando necessitarem de serem enviados. Isto torna possível a criação de uma solução mais simples e escalável para engenharia de tráfego. Nesta tese vamos explorar o uso de SR para avaliar a resiliencia da rede. O objectivo passa por desenhar e avaliar as soluções que forneçam reencaminhamento rápido após uma falha de uma ligação entre nós. Em particular, fornece a capacidade de realizar reencaminhamento rápido enquanto fornece uma grande percentagem de cobertura. Aproveitando as características das SDN e de SR, as nossas soluções permitem que o controlador pré compute os caminhos de backup necessários para instalar nos encaminhadores, mantendo o plano de dados em MPLS inalterado. A contribuição principal desta tese pode ser resumida em dois pontos: 1. Desenho de uma solução de reencaminhamento rápido em caso de faltas para Smart Grids, usando SR e SDN. 2. Fornecer uma avaliação exaustiva do algoritmo de modo a que se consiga compreender os seus benefícios e limitações. O algoritmo proposto utiliza vários comutadores que são utilizados como destinos intermédios, que garantem a entrega dos pacotes após a falha de uma ligação entre nós. Como tal, também propomos dois selectores de segmentos que fornecem reencaminhamento rápido mas com características diferentes. A primeira solução, Fast Segment Drop (FSD), selecciona um segmento próximo da origem do caminho em vez do segmento mais próximo do destino. Isto permite que os pacotes que atravessam a rede causem o menor overhead possível. O overhead devese ao número de segmentos usados em cada nó durante o caminho. Assim sendo, se escolhermos um segmento mais próximo do destino o overhead será maior. A segunda solução, Congestion Avoidance Segment (CAS), escolhe segmentos que podem aumentar o overhead mas que, em contraste, fornecem a capacidade de escolher o caminho com menor utilização. Deste modo pode-se evitar estrangulamentos existentes na rede. Para compararmos as nossas soluções implementamos um selector aleatório e o algoritmo TI-LFA [6]. Os resultados demonstram que para a maioria das topologias uma falha entre nós pode ser tolerada utilizando Loop Free Alternatives (LFA). No entanto ainda existem cerca de 20% dos casos que necessitam de utilizar um segmento para tolerar uma falha, enquanto que dois segmentos raramente são necessários. Também foi possível concluir que o nosso algoritmo fornece mais flexibilidade na escolha de segmentos do que TI-LFA visto que permite uma maior escolha de segmentos. Utilizando CAS é possível reduzir ligeiramente a congestão das ligações na rede em grids e em topologias reais.With the increase of power generation from renewable sources and with a growing energy demand, the traditional communication network underpinning the actual electric power grid needs an overhaul. As a response, the Smart Grid is a new generation of electric grids that aims to fulfill this goal. Smart Grids demand a set of properties that range from high availability to scalability and security. Therefore, the communication infrastructure plays an important role. Current Internet Protocol-based and Multiprotocol Layer Switching (MPLS) technologies have been suggested capable in achieving those needs. However, IP networks have problems to offer traffic engineering solutions and MPLS faces scalability problems due to the use of complex protocols such as RSVP-TE. A new network paradigm, Software-Defined Networks (SDN), is revolutionizing the way computer networks are built and operated, and is leading to the “softwarization” of networking. Showing promise to solve some of the above problems. However, smart grid operators may be reluctant to move all their network elements to SDN anytime soon. Fortunately, Segment routing, recently proposed by the IETF, allows SDN to be used in the context of MPLS networks. The data plane of Segment Routing is similar to MPLS as it uses segments that behave as MPLS labels and is managed in switches using similar actions. In this thesis we present algorithms for fast reroute in SR networks. We propose two solutions: Fast Segment Drop (FSD) that aims to minimize packet overhead and segment list size; and Congestion Avoidance Segment (CAS), a solution that provides traffic engineering by minimizing the maximum link load. The results indeed show that by using CAS reduces network congestion when compared with other algorithms. FSD provides higher coverage using just one segment thus reducing overhead

Traffic engineering multi-layer optimization for wireless mesh network transmission a campus network routing protocol transmission performance inhancement

This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel UniversityThe wireless mesh network is a potential network for the future due to its excellent inherent characteristic for dynamic self-healing, self-configuration and self-organization. It also has the advantage of easy interoperability networking and the ability to form multi-linked ad-hoc networks. It has a decentralized topology, is cheap and highly scalable. Furthermore, its ease in deployment and easy maintenance are other inherent networking qualities. These aforementioned qualities of the wireless mesh network bring advantages to transmission capability of heterogeneous networks. However, transmissions in wireless mesh network create comparative performance based challenges such as congestion, load-balancing, scalability over increasing networks and coverage capacity. Consequently, these challenges and problems in the routing and switching of packets in the wireless mesh network routing protocols led to a proposal on the resolution of these failures with a combination algorithm and a management based security for the network and its transmitted packets. There are equally contentious services like reliability of the network and quality of service for real-time multimedia traffic flows with other challenges such as path computation and selection in the wireless mesh network. This thesis is therefore a cumulative proposal to the resolution of the outlined challenges and open research areas posed by using wireless mesh network routing protocol. It advances the resolution of these challenges in the mesh environment using a hybrid optimization – traffic engineering, to increase the effectiveness and the reliability of the network. It also proffers a cumulative resolution of the diverse contributions on wireless mesh network routing protocol and transmission. Adaptation and optimization are carried out on the wireless mesh network designed network using traffic engineering mechanism and technique. The research examines the patterns of mesh packet transmission and evaluates the challenges and failures in the mesh network packet transmission. It develops a solution based algorithm for resolutions and proposes the traffic engineering based solution.. These resultant performances and analysis are usually tested and compared over wireless mesh IEEE802.11n or other older proposed documented solution. This thesis used a carefully designed campus mesh network to show a comparative evaluation of an optimal performance of the mesh nodes and routers over a normal IEE802.11n based wireless domain network to show differentiation by optimization using the created algorithms. Furthermore, the indexes of performance being the metric are used to measure the utility and the reliability, including capacity and throughput at the destination during traffic engineered transmission. In addition, the security of these transmitted data and packets are optimized under a traffic engineered technique. Finally, this thesis offers an understanding to the security contribution using traffic engineering resolution to create a management algorithm for processing and computation of the wireless mesh networks security needs. The results of this thesis confirmed, completed and extended the existing predictions with real measurement

A Closed-Loop Control Traffic Engineering System for the Dynamic Load Balancing of Inter-AS Traffic

Inter-AS outbound traffic engineering (TE) is a set of techniques for controlling inter-AS traffic exiting an autonomous system (AS) by assigning the traffic to the best egress points (i.e. routers or links) from which the traffic is forwarded to adjacent ASes towards the destinations. In practice, changing network conditions such as inter-AS traffic demand variation, link failures and inter-AS routing changes occur dynamically. These changes can make fixed outbound TE solutions inadequate and may subsequently cause inter-AS links to become congested. In order to overcome this problem, we propose the deployment of a closed-loop control traffic engineering system that makes outbound traffic robust to inter-AS link failures and adaptive to changing network conditions. The objective is to keep the inter-AS link utilization balanced under unexpected events while reducing service disruptions and reconfiguration overheads. Our evaluation results show that the proposed system can successfully achieve better load balancing with less service disruption and re-configuration overhead in comparison to alternative approaches

A Survey on the Path Computation Element (PCE) Architecture

Quality of Service-enabled applications and services rely on Traffic Engineering-based (TE) Label Switched Paths (LSP) established in core networks and controlled by the GMPLS control plane. Path computation process is crucial to achieve the desired TE objective. Its actual effectiveness depends on a number of factors. Mechanisms utilized to update topology and TE information, as well as the latency between path computation and resource reservation, which is typically distributed, may affect path computation efficiency. Moreover, TE visibility is limited in many network scenarios, such as multi-layer, multi-domain and multi-carrier networks, and it may negatively impact resource utilization. The Internet Engineering Task Force (IETF) has promoted the Path Computation Element (PCE) architecture, proposing a dedicated network entity devoted to path computation process. The PCE represents a flexible instrument to overcome visibility and distributed provisioning inefficiencies. Communications between path computation clients (PCC) and PCEs, realized through the PCE Protocol (PCEP), also enable inter-PCE communications offering an attractive way to perform TE-based path computation among cooperating PCEs in multi-layer/domain scenarios, while preserving scalability and confidentiality. This survey presents the state-of-the-art on the PCE architecture for GMPLS-controlled networks carried out by research and standardization community. In this work, packet (i.e., MPLS-TE and MPLS-TP) and wavelength/spectrum (i.e., WSON and SSON) switching capabilities are the considered technological platforms, in which the PCE is shown to achieve a number of evident benefits

Fast network recovery

The Internet is increasingly used to transport time-critical traffic. Applications like video conferencing, television, telephony and distributed games have strict requirements to the delay and availability offered by the underlying network. At the same time, connectivity failures caused by failures in network equipment is a part of everyday operation in large communication systems. The traditional recovery mechanisms used in IP networks are not designed with real-time applications in mind. The distributed nature of popular intradomain routing protocols allows them to eventually recover from any number of failures that leaves the network connected, but this isa time consuming process that can lead to unacceptable performance degradations for some applications. In this work, we argue that there is a need for fast recovery mechanisms that allow packet forwarding to continue over alternate paths immediately after a failure, before the routing protocol has converged on the altered topology. To give rapid response, such mechanisms should be proactive in the sense that an alternate route is readily available when a failure is discovered, and local, so that the recovery action can be effected by the node that discovers the failure. Further, care should be taken so that the shifting of recovered traffic to an alternate route does not lead to congestion and packet loss in other parts of the network. We present and investigate mechanisms that can respond quickly to failures or unexpected traffic shifts in the network. First, we evaluate the recovery strategy used in a network protocol called Resilient Packet Ring (RPR). The ring topology used in RPR allows the implementation of very fast protection mechanisms. We look at the performance of these mechanisms, and propose improvements that reduce packet loss and shorten the experienced disruption time after a link or node failure. Then, in the main part of this work, we focus on fast recovery in general mesh networks. We present Resilient Routing Layers (RRL) and Multiple Routing Configurations (MRC), which are methods for near-instantaneous recovery from component failures in packet networks. We discuss and evaluate our mechanisms with respect to state requirements and distribution of the recovered traffic. For MRC, we move on to present methods for reducing the chances of congestion after a recovery operation. We show that if we have knowledge about the traffic demands, we can use this information to create MRC recovery paths that avoid the most heavily used parts of the network. Finally, we show how the concepts used in RRL and MRC to give recovery from component failures also can be used to avoid congestion when there are sudden shifts in the traffic distribution. Our method is more flexible than traditional traffic engineering methods used in connectionless IP networks, since it does not involve changing link weights to respond to a changed traffic situation. Fast recovery mechanisms like those proposed in this work can help improve the stability and availability of IP networks. This is an important requirement for enabling new and existing real-time applications over general-purpose Internet infrastructure

An SDN-based Overlay Networking Solution for Transparent Multi-homed Vehicular Communications

This dissertation consists in the design and development of an Overlay Network for vehicular applications using the SDN paradigm, capable of supporting seamless handover and load balancing between multiple Vehicle-to-Infrastructure (V2I) networks, and also seamless handover of users' terminals between different vehicle zones, such as train carriages. The main contributions of this work are threefold: 1) the overlay SDN-based network architecture designed for vehicular applications such as trains, contemplating the support for multiple V2I operators and multiple gateways per vehicle (e.g., one per carriage); 2) the SDN orchestration component that implements the handover (performed by a User Terminal) from one carriage to another, without Internet connection interruption; and 3) the SDN orchestration component that implements the load-balancing of traffic over multiple V2I links that connect each carriage to the Internet, optimizing the utilization of available network resources and resulting QoS. All the features related to these contributions were implemented in a centralized SDN controller, which has a holistic view of the overlay network, which orchestrates the network hardware on-board of the vehicles. A Proof-of-Concept of the overlay network and the developed components was implemented using Virtual Machines emulating: the network elements of two carriages; the user terminals; a centralized orchestrator; an Internet gateway; and multiple V2I connections representing different operators. Different functional and performance tests were executed, targeting each component, which allowed to successfully validate each contribution

Hybrid SDN Evolution: A Comprehensive Survey of the State-of-the-Art

Software-Defined Networking (SDN) is an evolutionary networking paradigm which has been adopted by large network and cloud providers, among which are Tech Giants. However, embracing a new and futuristic paradigm as an alternative to well-established and mature legacy networking paradigm requires a lot of time along with considerable financial resources and technical expertise. Consequently, many enterprises can not afford it. A compromise solution then is a hybrid networking environment (a.k.a. Hybrid SDN (hSDN)) in which SDN functionalities are leveraged while existing traditional network infrastructures are acknowledged. Recently, hSDN has been seen as a viable networking solution for a diverse range of businesses and organizations. Accordingly, the body of literature on hSDN research has improved remarkably. On this account, we present this paper as a comprehensive state-of-the-art survey which expands upon hSDN from many different perspectives

Dynamic Virtual Network Restoration with Optimal Standby Virtual Router Selection

Title form PDF of title page, viewed on September 4, 2015Dissertation advisor: Deep MedhiVitaIncludes bibliographic references (pages 141-157)Thesis (Ph.D.)--School of Computing and Engineering and Department of Mathematics and Statistics. University of Missouri--Kansas City, 2015Network virtualization technologies allow service providers to request partitioned, QoS guaranteed and fault-tolerant virtual networks provisioned by the substrate network provider (i.e., physical infrastructure provider). A virtualized networking environment (VNE) has common features such as partition, flexibility, etc., but fault-tolerance requires additional efforts to provide survivability against failures on either virtual networks or the substrate network. Two common survivability paradigms are protection (proactive) and restoration (reactive). In the protection scheme, the substrate network provider (SNP) allocates redundant resources (e.g., nodes, paths, bandwidths, etc) to protect against potential failures in the VNE. In the restoration scheme, the SNP dynamically allocates resources to restore the networks, and it usually occurs after the failure is detected. In this dissertation, we design a restoration scheme that can be dynamically implemented in a centralized manner by an SNP to achieve survivability against node failures in the VNE. The proposed restoration scheme is designed to be integrated with a protection scheme, where the SNP allocates spare virtual routers (VRs) as standbys for the virtual networks (VN) and they are ready to serve in the restoration scheme after a node failure has been identified. These standby virtual routers (S-VR) are reserved as a sharedbackup for any single node failure, and during the restoration procedure, one of the S-VR will be selected to replace the failed VR. In this work, we present an optimal S-VR selection approach to simultaneously restore multiple VNs affected by failed VRs, where these VRs may be affected by failures within themselves or at their substrate host (i.e., power outage, hardware failures, maintenance, etc.). Furthermore, the restoration scheme is embedded into a dynamic reconfiguration scheme (DRS), so that the affected VNs can be dynamically restored by a centralized virtual network manager (VNM). We first introduce a dynamic reconfiguration scheme (DRS) against node failures in a VNE, and then present an experimental study by implementing this DRS over a realistic VNE using GpENI testbed. For this experimental study, we ran the DRS to restore one VN with a single-VR failure, and the results showed that with a proper S-VR selection, the performance of the affected VN could be well restored. Next, we proposed an Mixed-Integer Linear Programming (MILP) model with dual–goals to optimally select S-VRs to restore all VNs affected by VR failures while load balancing. We also present a heuristic algorithm based on the model. By considering a number of factors, we present numerical studies to show how the optimal selection is affected. The results show that the proposed heuristic’s performance is close to the optimization model when there were sufficient standby virtual routers for each virtual network and the substrate nodes have the capability to support multiple standby virtual routers to be in service simultaneously. Finally, we present the design of a software-defined resilient VNE with the optimal S-VR selection model, and discuss a prototype implementation on the GENI testbed.Introduction -- Literature survey -- Dynamic reconfiguration scheme in a VNE -- An experimental study on GpENI-VNI -- Optimal standby virtual router selection model -- Prototype design and implementation on GENI -- Conclusion and future work -- Appendix A. Resource Specification (RSpec) in GENI -- Appendix B. Optimal S-VR Selection Model in AMP

Mobility management in next generation networks

Master'sMASTER OF ENGINEERIN