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.

Network function virtualization (NFV) has drawn significant attention from both industry and academia as an important shift in telecommunication service provisioning. By decoupling network functions (NFs) from the physical devices on which they run, NFV has the potential to lead to significant reductions in operating expenses (OPEX) and capital expenses (CAPEX) and facilitate the deployment of new services with increased agility and faster time-to-value. The NFV paradigm is still in its infancy and there is a large spectrum of opportunities for the research community to develop new architectures, systems and applications, and to evaluate alternatives and trade-offs in developing technologies for its successful deployment. In this paper, after discussing NFV and its relationship with complementary fields of software defined networking (SDN) and cloud computing, we survey the state-of-the-art in NFV, and identify promising research directions in this area. We also overview key NFV projects, standardization efforts, early implementations, use cases, and commercial products.

/pdf/network-function-virtualization-state-of-the-art-and-29gg3feprt.pdf

Network Function Virtualization: State-of-the-Art and Research Challenges

The exponential traffic growth, demand for high speed wireless data communications, as well as incessant deployment of innovative wireless technologies, services, and applications, have put considerable pressure on the mobile network operators (MNOs). Consequently, cellular access network performance in terms of capacity, quality of service, and network coverage needs further considerations. In order to address the challenges, MNOs, as well as equipment vendors, have given significant attention to the small-cell schemes based on cloud radio access network (C-RAN). This is due to its beneficial features in terms of performance optimization, cost-effectiveness, easier infrastructure deployment, and network management. Nevertheless, the C-RAN architecture imposes stringent requirements on the fronthaul link for seamless connectivity. Digital radio over fiber-based common public radio interface (CPRI) is the fundamental means of distributing baseband samples in the C-RAN fronthaul. However, optical links which are based on CPRI have bandwidth and flexibility limitations. Therefore, these limitations might constrain or make them impractical for the next generation mobile systems which are envisaged not only to support carrier aggregation and multi-band but also envisioned to integrate technologies like millimeter-wave (mm-wave) and massive multiple-input multiple-output antennas into the base stations. In this paper, we present comprehensive tutorial on technologies, requirements, architectures, challenges, and proffer potential solutions on means of achieving an efficient C-RAN optical fronthaul for the next-generation network such as the fifth generation network and beyond. A number of viable fronthauling technologies such as mm-wave and wireless fidelity are considered and this paper mainly focuses on optical technologies such as optical fiber and free-space optical. We also present feasible means of reducing the system complexity, cost, bandwidth requirement, and latency in the fronthaul. Furthermore, means of achieving the goal of green communication networks through reduction in the power consumption by the system are considered.

Toward an Efficient C-RAN Optical Fronthaul for the Future Networks: A Tutorial on Technologies, Requirements, Challenges, and Solutions

Software Defined Networks discusses the historical networking environment that gave rise to SDN, as well as the latest advances in SDN technology. The book gives you the state of the art knowledge needed for successful deployment of an SDN, including: How to explain to the non-technical business decision makers in your organization the potential benefits, as well as the risks, in shifting parts of a network to the SDN model How to make intelligent decisions about when to integrate SDN technologies in a network How to decide if your organization should be developing its own SDN applications or looking to acquire these from an outside vendor How to accelerate the ability to develop your own SDN application, be it entirely novel or a more efficient approach to a long-standing problem Discusses the evolution of the switch platforms that enable SDN Addresses when to integrate SDN technologies in a network Provides an overview of sample SDN applications relevant to different industries Includes practical examples of how to write SDN applications

Software Defined Networks: A Comprehensive Approach

Software-Defined Networking (SDN) promises the vision of more flexible and manageable networks, but requires certain level of programmability in the data plane. Such a flexible, programmable data plane implementation is OpenFlow (OF) which these days is seen as primary model of SDN data plane. In this paper we focus on the limitations of OF in packet switching performance. We share some measurement results we collected using an OF 1.3 prototype based on Intel's Data Plane Development Kit (DPDK) and we also describe some optimization ideas. While OF 1.0 can be implemented on high-speed Ethernet switch hardware it has certain disadvantages in the area of flexibility. On the other hand OF 1.3 offers good-enough flexibility, but the poor performance of OF 1.3 implementations seems to represent a roadblock to SDN adoption. In this paper we argue that contrast to the common view, the overhead of flexibility is relatively low. We also argue that the apparent difference between a programmable data plane and a state of the art layered data plane is not primarily due to flexibility itself, but because the lack of optimization in case of flexible implementations.

Removing Roadblocks from SDN: OpenFlow Software Switch Performance on Intel DPDK

OpenFlow is an amazingly expressive dataplane programming language, but this expressiveness comes at a severe performance price as switches must do excessive packet classification in the fast path. The prevalent OpenFlow software switch architecture is therefore built on flow caching, but this imposes intricate limitations on the workloads that can be supported efficiently and may even open the door to malicious cache overflow attacks. In this paper we argue that instead of enforcing the same universal flow cache semantics to all OpenFlow applications and optimize for the common case, a switch should rather automatically specialize its dataplane piecemeal with respect to the configured workload. We introduce ESwitch, a novel switch architecture that uses on-the-fly template-based code generation to compile any OpenFlow pipeline into efficient machine code, which can then be readily used as fast path. We present a proof-of-concept prototype and we demonstrate on illustrative use cases that ESwitch yields a simpler architecture, superior packet processing speed, improved latency and CPU scalability, and predictable performance. Our prototype can easily scale beyond 100 Gbps on a single Intel blade even with complex OpenFlow pipelines.

/pdf/dataplane-specialization-for-high-performance-openflow-3a969fggs0.pdf

Dataplane Specialization for High-performance OpenFlow Software Switching

Telecom providers struggle with low service flexibility, increasing complexity and related costs. Although "cloud" has been an active field of research, there is currently little integration between the vast networking assets and data centres of telecom providers. UNIFY considers the entire network, from home networks up to data centre, as a "unified production environment" supporting virtualization, programmability and automation and guarantee a high level of agility for network operations and for deploying new, secure and quality services, seamlessly instantiatable across the entire infrastructure. UNIFY focuses on the required enablers and will develop an automated, dynamic service creation platform, leveraging fine-granular service chaining. A service abstraction model and a proper service creation language and a global orchestrator, with novel optimization algorithms, will enable the automatic optimal placement of networking, computing and storage components across the infrastructure. New management technologies based on experience from DCs, called Service Provider DevOps, will be developed and integrated into the orchestration architecture to cope with the dynamicity of services. The applicability of a universal node based on commodity hardware will be evaluated in order to support both network functions and traditional data centre workloads, with an investigation of the need of hardware acceleration.

Unifying Cloud and Carrier Network: EU FP7 Project UNIFY

Multiple packet traffic profiling models are created from known packet traffic flows that are labeled, where a label is an actual value of a factor influencing one or more characteristics of the known packet traffic flow. Features, which are different from the factors, are measured for each flow. Flow clusters are defined from the labeled traffic flows by processing their features and labels. The profiling models are created based on cluster information. When an unknown packet flow is received, the multiple packet traffic profiling models are evaluated according to a confidence and a completeness associated with each of the packet traffic profiling models. The packet traffic profiling model with a predetermined confidence and completeness is selected and applied to profile the unknown packet traffic flow.

Creating and using multiple packet traffic profiling models to profile packet flows

Datacenter networks offer a large degree of multipath in order to provide large bisectional bandwidth. The end-to-end performance is determined by the load-balancing strategy which needs to be designed to effectively manage congestion. Consequently, congestion aware load-balancing strategies such as CONGA or HULA have been designed. Recently, more and more applications that are hosted on cloud servers use multipath transport protocols such as MPTCP. However, in the presence of MPTCP, existing load-balancing schemes including ECMP, HULA or CONGA may lead to suboptimal forwarding decisions where multiple MPTCP subflows of one connection are pinned on the same bottleneck link.In this paper, we present MP-HULA, a transport layer multi-path aware load-balancing scheme using Programmable Data Planes. First, instead of tracking congestion information for the best path towards the destination, each MP-HULA switch tracks congestion information for the best-k paths to a destination through the neighbor switches. Second, we design MP-HULA using Programmable Data Planes, where each leaf switch can identify, using P4, which MPTCP subflow belongs to which connection. MP-HULA then load-balances different MPTCP subflows of a MPTCP connection on different next hops considering congestion state while aggregating bandwidth. Our evaluation shows that MP-HULA with MPTCP outperforms HULA in average flow completion time (2.1x at 50% load, 1.7x at 80% load).

https://dl.acm.org/doi/pdf/10.1145/3229591.3229596

Gergely Pongracz

Papers

Removing Roadblocks from SDN: OpenFlow Software Switch Performance on Intel DPDK

Dataplane Specialization for High-performance OpenFlow Software Switching

Unifying Cloud and Carrier Network: EU FP7 Project UNIFY

Creating and using multiple packet traffic profiling models to profile packet flows

MP-HULA: Multipath Transport Aware Load Balancing Using Programmable Data Planes