Reliability management framework for softwarized networks

Title from PDF of title page viewed February 11, 2022Dissertation advisor: Sejun SongVitaIncludes bibliographical references (page 100-110)Thesis (Ph.D.)--School of Computing and Engineering. University of Missouri--Kansas City, 2021The Software-Defined Networking (SDN) technologies promise to enhance the performance, reliability, and cost of managing both wired and wireless network infrastructures, functions, controls, and services (i.e., Internet of Things). However, centralized reliability management in Softwareization architecture poses both scalability and latency challenges. Significantly, the current OpenFlow Discovery Protocol (OFDP) in SDN induces substantial scalability, accuracy, and latency hurdles due to its gossipy, centralized, periodic, and tardy protocol. This dissertation proposes a novel reliability management framework, which efficiently orchestrates different reliability monitoring mechanisms over SDN networks and synchronizes the control messages among various applications. The proposed framework facilitates multiple discovery frequency timers for each target over different stratum instead of using a uniform discovery timer for the entire network. It supports many common reliability monitoring factors for registered applications by analyzing offline and online network architecture information such as network topologies, traffic flows, virtualization architectures, and protocols. The framework consists of a high availability registration platform (HARP) and the topology-aware reliability management (TARman) and Bug Detection, Debugging, and Isolation (BuDDI) protocol facilities. The reliability management framework is implemented on both Ryu and Cisco’s OpenDayLight (ODL) controllers. Extensive Mininet experimental results validate that framework significantly improves discovery message efficiency and makes the control traffic less bursty than OFDP with a uniform timer. It also reduces the network status discovery delay without increasing the control overhead. Our reliability management framework also proposes a novel network reliability cost model to ensure that the SLA covers customer service impact and damage. We classify network outages and calculate their effect on the network services to formulate a cost-based model. Besides, we have performed evaluations using various campus network outage scenarios. The proposed cost-based model enables customers to identify the service impact of unplanned network outages to their networks instead of entirely depending on the service provider’s data.Introduction -- Related work -- Measurement and analysis of an access network availability -- SDN control path network reliability -- SDN control plane network reliability -- Reliability cost model -- Summary and future wor

Energy Saving and Virtualization Technologies in Switching

Switching is the key functionality for many devices like electronic Router and Switch, optical Router, Network on Chips (NoCs) and so on. Basically, switching is responsible for moving data unit from one port/location to another (or multiple) port(s)/location(s). In past years, the high capacity, low delay were the main concerns when designing high-end switching unit. As new demands, requests and technologies emerge, flexibility and low power cost switching design become to weight the same as throughput and delay. On one hand, highly flexible (i.e, programming ability) switching can cope with variable needs stem from new applications (i.e, VoIP) and popular user behavior (i.e, p2p downloading); on the other hand, reduce the energy and power dissipation for switching could not only save bills and build echo system but also expand components life time. Many research efforts have been devoted to increase switching flexibility and reduce its power cost. In this thesis work, we consider to exploit virtualization as the main technique to build flexible software router in the first part, then in the second part we draw our attention on energy saving in NoC (i.e, a switching fabric designed to handle the on chip data transmission) and software router. In the first part of the thesis, we consider the virtualization inside Software Routers (SRs). SR, i.e, routers running in commodity Personal Computers (PCs), become an appealing solution compared to traditional Proprietary Routing Devices (PRD) for various reasons such as cost (the multi-vendor hardware used by SRs can be cheap, while the equipment needed by PRDs is more expensive and their training cost is higher), openness (SRs can make use of a large number of open source networking applications, while PRDs are more closed) and flexibility. The forwarding performance provided by SRs has been an obstacle to their deployment in real networks. For this reason, we proposed to aggregate multiple routing units that form an powerful SR known as the Multistage Software Router (MSR) to overcome the performance limitation for a single SR. Our results show that the throughput can increase almost linearly as the number of the internal routing devices. But some other features related to flexibility (such as power saving, programmability, router migration or easy management) have been investigated less than performance previously. We noticed that virtualization techniques become reality thanks to the quick development of the PC architectures, which are now able to easily support several logical PCs running in parallel on the same hardware. Virtualization could provide many flexible features like hardware and software decoupling, encapsulation of virtual machine state, failure recovery and security, to name a few. Virtualization permits to build multiple SRs inside one physical host and a multistage architecture exploiting only logical devices. By doing so, physical resources can be used in a more efficient way, energy savings features (switching on and off device when needed) can be introduced and logical resources could be rented on-demand instead of being owned. Since virtualization techniques are still difficult to deploy, several challenges need to be faced when trying to integrate them into routers. The main aim of the first part in this thesis is to find out the feasibility of the virtualization approach, to build and test virtualized SR (VSR), to implement the MSR exploiting logical, i.e. virtualized, resources, to analyze virtualized routing performance and to propose improvement techniques to VSR and virtual MSR (VMSR). More specifically, we considered different virtualization solutions like VMware, XEN, KVM to build VSR and VMSR, being VMware a closed source solution but with higher performance and XEN/KVM open source solutions. Firstly we built and tested each single component of our multistage architecture (i.e, back-end router, load balancer )inside the virtual infrastructure, then and we extended the performance experiments with more complex scenarios like multiple Back-end Router (BR) or Load Balancer (LB) which cooperate to route packets. Our results show that virtualization could introduce 40~\% performance penalty compare with the hardware only solution. Keep the performance limitation in mind, we developed the whole VMSR and we obtained low throughput with 64B packet flow as expected. To increase the VMSR throughput, two directions could be considered, the first one is to improve the single component ( i.e, VSR) performance and the other is to work from the topology (i.e, best allocation of the VMs into the hardware ) point of view. For the first method, we considered to tune the VSR inside the KVM and we studied closely such as Linux driver, scheduler, interconnect methodology which could impact the performance significantly with proper configuration; then we proposed two ways for the VMs allocation into physical servers to enhance the VMSR performance. Our results show that with good tuning and allocation of VMs, we could minimize the virtualization penalty and get reasonable throughput for running SRs inside virtual infrastructure and add flexibility functionalities into SRs easily. In the second part of the thesis, we consider the energy efficient switching design problem and we focus on two main architecture, the NoC and MSR. As many research works suggest, the energy cost in the Communication Technologies ( ICT ) is constantly increasing. Among the main ICT sectors, a large portion of the energy consumption is contributed by the telecommunication infrastructure and their devices, i.e, router, switch, cell phone, ip TV settle box, storage home gateway etc. More in detail, the linecards, links, System on Chip (SoC) including the transmitter/receiver on these variate devices are the main power consuming units. We firstly present the work on the power reduction of the data transmission in SoC, which is carried out by the NoC. NoC is an approach to design the communication subsystem between different Processing Units (PEs) in a SoC. PEs could be different elements such as CPU, memory, digital signal/analog signal processor etc. Different PEs performs specific tasks depending on the applications running on the chip. Different tasks need to exchange data information among each other, thus flits ( chopped packet with limited header information ) are generated by PEs. The flits are injected into the NoC by the proper interface and routed until reach the destination PEs. For the whole procedure, the NoC behaves as a packet switch network. Studies show that in general the information processing in the PEs only consume 60~\% energy while the remaining 40~\% are consumed by the NoC. More importantly, as the current network designing principle, the NoC capacity is devised to handle the peak load. This is a clear sign for energy saving when the network load is low. In our work, we considered to exploit Dynamic Voltage and Frequency Scaling (DVFS) technique, which can jointly decrease or increase the system voltage and frequency when necessary, i.e, decrease the voltage and frequency at low load scenario to save energy and reduce power dissipation. More precisely, we studied two different NoC architectures for energy saving, namely single plane chip and multi-plane chip architecture. In both cases we have a very strict constraint to be that all the links and transmitter/receivers on the same plane work at the same frequency/voltage to avoid synchronization problem. This is the main difference with many existing works in the literature which usually assume different links can work at different frequency, that is hard to be implemented in reality. For the single plane NoC, we exploited different routing schemas combined with DVFS to reduce the power for the whole chip. Our results haven been compared with the optimal value obtained by modeling the power saving formally as a quadratic programming problem. Results suggest that just by using simple load balancing routing algorithm, we can save considerable energy for the single chip NoC architecture. Furthermore, we noticed that in the single plane NoC architecture, the bottleneck link could limit the DVFS effectiveness. Then we discovered that multiplane NoC architecture is fairly easy to be implemented and it could help with the energy saving. Thus we focus on the multiplane architecture and we found out that DVFS could be more efficient when we concentrate more traffic into one plane and send the remaining flows to other planes. We compared load concentration and load balancing with different power modeling and all simulation results show that load concentration is better compared with load balancing for multiplan NoC architecture. Finally, we also present one of the the energy efficient MSR design technique, which permits the MSR to follow the day-night traffic pattern more efficiently with our on-line energy saving algorithm

Extension of an evaluation testbed for fog computing Infrastructures and applications

Fog computing is an emerging system architecture in the cloud and Internet of Everything realm. It aims to distribute computing, storage, and control closer to the user. In the last few years work in this field has gained traction. Publications and research projects are increasing and just recently work on an open standard has been started. The research community and industry are proposing new approaches, algorithms, and system-architectures on a very fast pace. However, it remains difficult to evaluate and test these proposals. Particularly, because real-world testbeds are expensive and hard to set up. This work is continuing the development of the open source project EmuFog. EmuFog is an extensible and scalable emulation framework for fog computing infrastructures. It supports researchers, system-architects and developers by providing a framework to test application behavior in fog architectures. Furthermore, evaluation of algorithms for edge identification, fog node, and application placement can be carried out on large systems. This work extends the previous system architecture to enable multi-tiered fog nodes. That is, the ability to run multiple applications on a single fog node instance. Furthermore, usage of custom placement algorithms is simplified. Additionally, groundwork for resource management was introduced to the system architecture.Fog Computing ist eine aufkommende System-Architektur im Cloud und Internet of Everything Umfeld. Fog Computing zielt darauf ab, Rechenleistung, Datenspeicher und Kontrollinstanzen näher zu den Nutzern zu bringen. In den letzten Jahren hat Forschung in diesem Kontext stark zugenommen. Insbesondere die Anzahl an Forschungsprojekten und Veröffentlichungen. Zusätzlich wird an einem gemeinsamen Standard gearbeitet. Die Forschergemeinde und die Industrie schlagen neue Lösungsansätze, Fog Algorithmen und System-Architekuren mit hoher Frequenz vor. Allerdings ist es schwierig diese Vorschläge zu evaluieren. Insbesondere sind Testumgebungen auf echter Hardware für Fog Computing teuer, umständlich und selten. Diese Arbeit setzt die Entwicklung des open-source Projekts EmuFog fort. EmuFog ist ein erweiterbares, flexibles und skalierbares Emulations-Framework um Fog Computing Infrastrukturen zu testen. Es unterstützt Forscher, System Architekten und Entwickler, indem es Nutzern ermöglicht, Software Anwendungen in Fog Architekturen zu testen. Zusätzlich ist es möglich Algorithmen für Netzwerkkantenerkennung, Fog Knoten Platzierung und Anwendungsplatzierungen auf großen Netzwerken zu evaluieren. In dieser Arbeit wurde die vorherige System-Architektur erweitert, um multi-tiered Fog Knoten zu ermöglichen. Multi-tiered Fog Knoten ermöglichen es, mehr als eine Applikation pro Instanz auszuführen. Außerdem wurde die Ausführung von Placement Algorithmen vereinfacht und Grundlagen für Ressourcen Verwaltung wurde zu der Sytem-Architektur hinzugefügt

Reconfigurable network systems and software-defined networking

Modern high-speed networks have evolved from relatively static networks to highly adaptive networks facilitating dynamic reconfiguration. This evolution has influenced all levels of network design and management, introducing increased programmability and configuration flexibility. This influence has extended from the lowest level of physical hardware interfaces to the highest level of network management by software. A key representative of this evolution is the emergence of softwaredefined networking (SDN). In this paper, we review the current state of the art in reconfigurable network systems, covering hardware reconfiguration, SDN, and the interplay between them. We take a top-down approach, starting with a tutorial on software-defined networks. We then continue to discuss programming languages as the linking element between different levels of software and hardware in the network. We review electronic switching systems, highlighting programmability and reconfiguration aspects, and describe the trends in reconfigurable network elements. Finally, we describe the state of the art in the integration of photonic transceiver and switching elements with electronic technologies, and consider the implications for SDN and reconfigurable network systems.This work was jointly supported by the UKs Engineering and Physical Sciences Research Council (EPSRC) Internet Project EP/H040536/1, an EPSRC Research Fellowship grant to Philip Watts (EP/I004157/2), and DARPA and AFRL under contract FA8750-11-C-0249.This is the final version of the article. It first appeared from IEEE via http://dx.doi.org/10.1109/JPROC.2015.243573

A new approach to detecting failures in distributed systems

textFault-tolerant distributed systems often handle failures in two steps: first, detect the failure and, second, take some recovery action. A common approach to detecting failures is end-to-end timeouts, but using timeouts brings problems. First, timeouts are inaccurate: just because a process is unresponsive does not mean that process has failed. Second, choosing a timeout is hard: short timeouts can exacerbate the problem of inaccuracy, and long timeouts can make the system wait unnecessarily. In fact, a good timeout value—one that balances the choice between accuracy and speed—may not even exist, owing to the variance in a system’s end-to-end delays. ƃis dissertation posits a new approach to detecting failures in distributed systems: use information about failures that is local to each component, e.g., the contents of an OS’s process table. We call such information inside information, and use it as the basis in the design and implementation of three failure reporting services for data center applications, which we call Falcon, Albatross, and Pigeon. Falcon deploys a network of software modules to gather inside information in the system, and it guarantees that it never reports a working process as crashed by sometimes terminating unresponsive components. ƃis choice helps applications by making reports of failure reliable, meaning that applications can treat them as ground truth. Unfortunately, Falcon cannot handle network failures because guaranteeing that a process has crashed requires network communication; we address this problem in Albatross and Pigeon. Instead of killing, Albatross blocks suspected processes from using the network, allowing applications to make progress during network partitions. Pigeon renounces interference altogether, and reports inside information to applications directly and with more detail to help applications make better recovery decisions. By using these services, applications can improve their recovery from failures both quantitatively and qualitatively. Quantitatively, these services reduce detection time by one to two orders of magnitude over the end-to-end timeouts commonly used by data center applications, thereby reducing the unavailability caused by failures. Qualitatively, these services provide more specific information about failures, which can reduce the logic required for recovery and can help applications better decide when recovery is not necessary.Computer Science

Datacenter Traffic Control: Understanding Techniques and Trade-offs

Datacenters provide cost-effective and flexible access to scalable compute and storage resources necessary for today's cloud computing needs. A typical datacenter is made up of thousands of servers connected with a large network and usually managed by one operator. To provide quality access to the variety of applications and services hosted on datacenters and maximize performance, it deems necessary to use datacenter networks effectively and efficiently. Datacenter traffic is often a mix of several classes with different priorities and requirements. This includes user-generated interactive traffic, traffic with deadlines, and long-running traffic. To this end, custom transport protocols and traffic management techniques have been developed to improve datacenter network performance. In this tutorial paper, we review the general architecture of datacenter networks, various topologies proposed for them, their traffic properties, general traffic control challenges in datacenters and general traffic control objectives. The purpose of this paper is to bring out the important characteristics of traffic control in datacenters and not to survey all existing solutions (as it is virtually impossible due to massive body of existing research). We hope to provide readers with a wide range of options and factors while considering a variety of traffic control mechanisms. We discuss various characteristics of datacenter traffic control including management schemes, transmission control, traffic shaping, prioritization, load balancing, multipathing, and traffic scheduling. Next, we point to several open challenges as well as new and interesting networking paradigms. At the end of this paper, we briefly review inter-datacenter networks that connect geographically dispersed datacenters which have been receiving increasing attention recently and pose interesting and novel research problems.Comment: Accepted for Publication in IEEE Communications Surveys and Tutorial