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

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.

Software defined networks

Residue Number System (RNS) is a non-weighted number system which was proposed by Garner back in 1959 to achieve fast implementation of addition, subtraction and multiplication operations in special-purpose computations. Unfortunately, RNS did not turn out as a popular alternative to two?s complement number system in those days. The rigidity of instruction set architectures of the market-dominant computers and microprocessors then has been the main barrier to sustain the development of RNS-based applications. In recent years, technological advancement in semiconductor technology has revived the interests to reconsider RNS for application-specific computing. There are at least two unique motivations which make RNS computations more attractive and applicable in modern digital signal processing applications. Firstly, the modular and distributive properties of RNS are used to achieve performance improvements especially in the emerging distributed and ubiquitous computing platforms such as cloud, wireless ad hoc networks, and applications which require tolerance against soft error. Secondly, energy efficiency becomes a key driver in the continual densification of complementary metal oxide semiconductor (CMOS) digital integrated circuits. The high degree of computational parallelism in RNS offers new degree of freedom to optimize energy performance, particularly for very long word length arithmetic such as those involved in the hardware implementation of cryptographic algorithms. Our aim in this paper is to show this revolution by discussing interesting development in RNS and foster the innovative use of RNS for more applications. Different applications of RNS are investigated to demonstrate how this unconventional number system can be leveraged to benefit their implementation.

Residue Number Systems: A New Paradigm to Datapath Optimization for Low-Power and High-Performance Digital Signal Processing Applications

Network devices have always been considered as configurable black boxes until the emergence of software-defined networking (SDN). SDN enables the networks to be programmed according to the user requirements; furthermore, it allows the network to be easily modified to suit transient demands. However, how do we program the network? SDN-compliant switches offer a low-level interface that makes programming error-prone. The controllers provide application programming interfaces, but still low-level, limited, and inflexible. High-level languages have the potential to be a better alternative to program the network. There exist several SDN programming languages implementing different sets of functionalities, and focusing on solving various issues. In face of all this diversity, no published paper outlines a pragmatic view allowing to compare the SDN languages. This paper presents a systematic survey of up-to-date OpenFlow-based SDN programming languages. Our approach relies on a taxonomy comprising all prominent features found in those languages. A detailed review of the existing works is carried out investigating the foundational parts of the languages with their contributions. Examples are discussed to illustrate the fundamental abstractions. Last, all gathered information is summarized, discussing the main ongoing research efforts and challenges. Future abstractions and features to be incorporated into the next generations of SDN programming languages are also considered.

A Survey on SDN Programming Languages: Toward a Taxonomy

The large bulk of packets/flows in future core networks will require a highly efficient header processing in the switching elements. Simplifying lookup in core network switching elements is capital to transport data at high rates and with low latency. Flexible network hardware combined with agile network control is also an essential property for future software-defined networking. We argue that only further decoupling between the control and data planes will unlock the flexibility and agility in SDN for the design of new network solutions for core networks. This article proposes a new approach named KeyFlow to build a flexible network-fabricbased model. It replaces the table lookup in the forwarding engine by elementary operations relying on a residue number system. This provides us tools to design a stateless core network by still using OpenFlow centralized control. A proof of concept prototype is validated using the Mininet emulation environment and OpenFlow 1.0. The results indicate RTT reduction above 50 percent, especially for networks with densely populated flow tables. KeyFlow achieves above 30 percent reduction in keeping active flow state in the network.

Keyflow: a prototype for evolving SDN toward core network fabrics

Parâmetros balizadores para experimentos com comutadores OpenFlow: avaliação experimental baseada em medições de alta precisão.

A comprehensive data plane power consumption analysis of an OpenFlow 1.0 switch broken down into its design modules is presented, and KeyFlow as an alternative solution is proposed, since it eliminates a flow table lookup by reducing 53.7% of the overall power consumption.

Rafael Emerick Z. de Oliveira

Papers

Keyflow: a prototype for evolving SDN toward core network fabrics

Parâmetros balizadores para experimentos com comutadores OpenFlow: avaliação experimental baseada em medições de alta precisão.

Tackling OpenFlow power hog in core networks with KeyFlow