The Internet has led to the creation of a digital society, where (almost) everything is connected and is accessible from anywhere. However, despite their widespread adoption, traditional IP networks are complex and very hard to manage. It is both difficult to configure the network according to predefined policies, and to reconfigure it to respond to faults, load, and changes. To make matters even more difficult, current networks are also vertically integrated: the control and data planes are bundled together. Software-defined networking (SDN) is an emerging paradigm that promises to change this state of affairs, by breaking vertical integration, separating the network's control logic from the underlying routers and switches, promoting (logical) centralization of network control, and introducing the ability to program the network. The separation of concerns, introduced between the definition of network policies, their implementation in switching hardware, and the forwarding of traffic, is key to the desired flexibility: by breaking the network control problem into tractable pieces, SDN makes it easier to create and introduce new abstractions in networking, simplifying network management and facilitating network evolution. In this paper, we present a comprehensive survey on SDN. We start by introducing the motivation for SDN, explain its main concepts and how it differs from traditional networking, its roots, and the standardization activities regarding this novel paradigm. Next, we present the key building blocks of an SDN infrastructure using a bottom-up, layered approach. We provide an in-depth analysis of the hardware infrastructure, southbound and northbound application programming interfaces (APIs), network virtualization layers, network operating systems (SDN controllers), network programming languages, and network applications. We also look at cross-layer problems such as debugging and troubleshooting. In an effort to anticipate the future evolution of this new paradigm, we discuss the main ongoing research efforts and challenges of SDN. In particular, we address the design of switches and control platforms—with a focus on aspects such as resiliency, scalability, performance, security, and dependability—as well as new opportunities for carrier transport networks and cloud providers. Last but not least, we analyze the position of SDN as a key enabler of a software-defined environment.

https://publications.uni.lu/bitstream/10993/20596/1/survey_on_SDN.pdf

Software-Defined Networking: A Comprehensive Survey

The idea of programmable networks has recently re-gained considerable momentum due to the emergence of the Software-Defined Networking (SDN) paradigm. SDN, often referred to as a ''radical new idea in networking'', promises to dramatically simplify network management and enable innovation through network programmability. This paper surveys the state-of-the-art in programmable networks with an emphasis on SDN. We provide a historic perspective of programmable networks from early ideas to recent developments. Then we present the SDN architecture and the OpenFlow standard in particular, discuss current alternatives for implementation and testing of SDN-based protocols and services, examine current and future SDN applications, and explore promising research directions based on the SDN paradigm.

/pdf/a-survey-of-software-defined-networking-past-present-and-6tt309ed7r.pdf

A Survey of Software-Defined Networking: Past, Present, and Future of Programmable Networks

Software-Defined Networking (SDN) is an emerging paradigm that promises to change this state of affairs, by breaking vertical integration, separating the network's control logic from the underlying routers and switches, promoting (logical) centralization of network control, and introducing the ability to program the network. The separation of concerns introduced between the definition of network policies, their implementation in switching hardware, and the forwarding of traffic, is key to the desired flexibility: by breaking the network control problem into tractable pieces, SDN makes it easier to create and introduce new abstractions in networking, simplifying network management and facilitating network evolution. In this paper we present a comprehensive survey on SDN. We start by introducing the motivation for SDN, explain its main concepts and how it differs from traditional networking, its roots, and the standardization activities regarding this novel paradigm. Next, we present the key building blocks of an SDN infrastructure using a bottom-up, layered approach. We provide an in-depth analysis of the hardware infrastructure, southbound and northbound APIs, network virtualization layers, network operating systems (SDN controllers), network programming languages, and network applications. We also look at cross-layer problems such as debugging and troubleshooting. In an effort to anticipate the future evolution of this new paradigm, we discuss the main ongoing research efforts and challenges of SDN. In particular, we address the design of switches and control platforms -- with a focus on aspects such as resiliency, scalability, performance, security and dependability -- as well as new opportunities for carrier transport networks and cloud providers. Last but not least, we analyze the position of SDN as a key enabler of a software-defined environment.

This issue of the IBM Systems Journal explores a broad set of ideas and approaches to autonomic computing--some first steps in what we see as a journey to create more self-managing computing systems Autonomic computing represents a collection and integration of technologies that enable the creation of an information technology computing infrastructure for IBM's agenda for the next era of computing--e-business on demand This paper presents an overview of IBM's autonomic computing initiative It examines the genesis of autonomic computing, the industry and marketplace drivers, the fundamental characteristics of autonomic systems, a framework for how systems will evolve to become more self-managing, and the key role for open industry standards needed to support autonomic behavior in heterogeneous system environments Technologies explored in each of the papers presented in this issue are introduced for the reader

https://cs.drexel.edu/~spiros/teaching/CS576/papers/autonomic.pdf

The dawning of the autonomic computing era

Emerging mega-trends (e.g., mobile, social, cloud, and big data) in information and communication technologies (ICT) are commanding new challenges to future Internet, for which ubiquitous accessibility, high bandwidth, and dynamic management are crucial. However, traditional approaches based on manual configuration of proprietary devices are cumbersome and error-prone, and they cannot fully utilize the capability of physical network infrastructure. Recently, software-defined networking (SDN) has been touted as one of the most promising solutions for future Internet. SDN is characterized by its two distinguished features, including decoupling the control plane from the data plane and providing programmability for network application development. As a result, SDN is positioned to provide more efficient configuration, better performance, and higher flexibility to accommodate innovative network designs. This paper surveys latest developments in this active research area of SDN. We first present a generally accepted definition for SDN with the aforementioned two characteristic features and potential benefits of SDN. We then dwell on its three-layer architecture, including an infrastructure layer, a control layer, and an application layer, and substantiate each layer with existing research efforts and its related research areas. We follow that with an overview of the de facto SDN implementation (i.e., OpenFlow). Finally, we conclude this survey paper with some suggested open research challenges.

A Survey on Software-Defined Networking

Write amplification is a critical factor limiting the random write performance and write endurance in storage devices based on NAND-flash memories such as solid-state drives (SSD). The impact of garbage collection on write amplification is influenced by the level of over-provisioning and the choice of reclaiming policy. In this paper, we present a novel probabilistic model of write amplification for log-structured flash-based SSDs. Specifically, we quantify the impact of over-provisioning on write amplification analytically and by simulation assuming workloads of uniformly-distributed random short writes. Moreover, we propose modified versions of the greedy garbage-collection reclaiming policy and compare their performance. Finally, we analytically evaluate the benefits of separating static and dynamic data in reducing write amplification, and how to address endurance with proper wear leveling.

/pdf/write-amplification-analysis-in-flash-based-solid-state-29qqajkwed.pdf

Write amplification analysis in flash-based solid state drives

This document specifies the Forwarding and Control Element Separation
(ForCES) protocol. The ForCES protocol is used for communications
between Control Elements (CEs) and Forwarding Elements (FEs) in a
ForCES Network Element (ForCES NE). This specification is intended to
meet the ForCES protocol requirements defined in RFC 3654. Besides the
ForCES protocol, this specification also defines the requirements for
the Transport Mapping Layer (TML). [STANDARDS-TRACK]

Forwarding and Control Element Separation (ForCES) Protocol Specification

A method for facilitating fast reconstruction of metadata structures on a memory storage device includes writing a plurality of checkpoints holding a root of metadata structures in an increasing order of timestamps to a plurality of blocks respectively on the memory storage device utilizing a memory controller, where each checkpoint is associated with a timestamp, and wherein the last-written checkpoint contains a root to the latest metadata information from where metadata structures are reconstructed.

Method to efficiently locate meta-data structures on a flash-based storage device

A memory management system and method for managing memory blocks of a memory device of a computer. The system includes a free block data structure including free memory blocks for writing, and sorting the free memory blocks in a predetermined order based on block write-erase endurance cycle count and receiving new user-write requests to update existing data and relocation write requests to relocate existing data separately, a user-write block pool for receiving youngest blocks holding user-write data (i.e., any page being updated frequently) from the free block data structure, a relocation block pool for receiving oldest blocks holding relocation data (i.e., any page being updated infrequently) from the free block data structure, and a garbage collection pool structure for selecting at least one of user-write blocks and relocation blocks for garbage collection, wherein the selected block is moved back to the free block data structure upon being relocated and erased.

Write-erase endurance lifetime of memory storage devices

This paper presents a data-placement scheme for log-structured flash translation layers (FTLs), with the dual aims of reducing write amplification due to garbage collection and flash wear-out due to block erasing and programming. The central idea is to identify and place data that is expected to change frequently together in young flash blocks that are far from wearing out, and infrequently changing data in old blocks where it can be expected to stay longer. In previous work, garbage collection and wear levelling were treated separately, and the importance of data placement was largely ignored. We propose a new scheme, called container marking, to combine data placement, garbage collection, and wear levelling in a single mechanism, thus improving both the random write performance and the endurance. Each flash block is a data container that is assigned an activeness marker indicating how frequently the data it stores is updated. A simple solution for dynamically tracking data's activeness that adapts to utilizations is presented. The system is implemented in a Java1-based flash simulator, and is shown to reduce write amplification and wear-out in synthetic and trace-driven workloads.

Robert Haas

Papers

Write amplification analysis in flash-based solid state drives

Forwarding and Control Element Separation (ForCES) Protocol Specification

Method to efficiently locate meta-data structures on a flash-based storage device

Write-erase endurance lifetime of memory storage devices

Container Marking: Combining Data Placement, Garbage Collection and Wear Levelling for Flash