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

Although there is tremendous interest in designing improved networks for data centers, very little is known about the network-level traffic characteristics of data centers today. In this paper, we conduct an empirical study of the network traffic in 10 data centers belonging to three different categories, including university, enterprise campus, and cloud data centers. Our definition of cloud data centers includes not only data centers employed by large online service providers offering Internet-facing applications but also data centers used to host data-intensive (MapReduce style) applications). We collect and analyze SNMP statistics, topology and packet-level traces. We examine the range of applications deployed in these data centers and their placement, the flow-level and packet-level transmission properties of these applications, and their impact on network and link utilizations, congestion and packet drops. We describe the implications of the observed traffic patterns for data center internal traffic engineering as well as for recently proposed architectures for data center networks.

/pdf/network-traffic-characteristics-of-data-centers-in-the-wild-43qhxtldqh.pdf

Network traffic characteristics of data centers in the wild

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.

Mininet is a system for rapidly prototyping large networks on the constrained resources of a single laptop The lightweight approach of using OS-level virtualization features, including processes and network namespaces, allows it to scale to hundreds of nodes Experiences with our initial implementation suggest that the ability to run, poke, and debug in real time represents a qualitative change in workflow We share supporting case studies culled from over 100 users, at 18 institutions, who have developed Software-Defined Networks (SDN) Ultimately, we think the greatest value of Mininet will be supporting collaborative network research, by enabling self-contained SDN prototypes which anyone with a PC can download, run, evaluate, explore, tweak, and build upon

/pdf/a-network-in-a-laptop-rapid-prototyping-for-software-defined-27edokofdp.pdf

A network in a laptop: rapid prototyping for software-defined networks

Monitoring transit traffic at one or more points in a network is of interest to network operators for reasons of traffic accounting, debugging or troubleshooting, forensics, and traffic engineering Previous research in the area has focused on deriving a placement of monitors across the network towards the end of maximizing the monitoring utility of the network operator for a given traffic routing However, both traffic characteristics and measurement objectives can dynamically change over time, rendering a previously optimal placement of monitors suboptimal It is not feasible to dynamically redeploy/reconfigure measurement infrastructure to cater to such evolving measurement requirements We address this problem by strategically routing traffic sub-populations over fixed monitors We refer to this approach as MeasuRouting The main challenge for MeasuRouting is to work within the constraints of existing intra-domain traffic engineering operations that are geared for efficiently utilizing bandwidth resources, or meeting Quality of Service (QoS) constraints, or both A fundamental feature of intra-domain routing, that makes MeasuRouting feasible, is that intra-domain routing is often specified for aggregate flows MeasuRouting, can therefore, differentially route components of an aggregate flow while ensuring that the aggregate placement is compliant to original traffic engineering objectives In this paper we present a theoretical framework for MeasuRouting Furthermore, as proofs-of-concept, we present synthetic and practical monitoring applications to showcase the utility enhancement achieved with MeasuRouting

MeasuRouting: A Framework for Routing Assisted Traffic Monitoring

Our work addresses the problem of revision control for flow state management in SDN-enabled networks, so that the underlying data plane might be able to provide better state protection, provenance, ease of programmability, and support for multiple applications. Inspired by the revision control tools in the software development world, we propose an abstraction and a system called GitFlow, which provides flow state revisioning in the SDN context. The core idea of GitFlow is to run a repository server to maintain the authoritative copy of the flow configuration state and track additional meta data for each evolving snapshot of the flow state. When multiple applications make incremental commits to state, our system also automates conflict resolution by rebasing new flow state with committed flow state. We envision that our revision control abstraction will provide safety in the data plane and better programmability in the control plane.

GitFlow: flow revision management for software-defined networks

A method for routing-assisted traffic monitoring includes providing a set of flows, each flow having an associated ingress routing device and an associated egress routing device. A controller determines a micro-flowset routing for the set of flows, the micro-flowset routing defining which of a set of directed links connecting a plurality of routing devices are used to route each of the flows from the respective ingress routing device to the respective egress routing device. The controller transmits flow information to at least a first routing device of the plurality of routing devices according to the micro-flowset routing, the flow information defining which of the set of directed links are to be used to route at least one flow entering the first routing device to a second routing device of the plurality of routing devices.

Method for routing-assisted traffic monitoring

Monitoring end-to-end paths in an overlay network is essential for evaluating end-system performance and for troubleshooting anomalous behavior. However, conducting measurements between all pairs of overlay nodes can be cumbersome and expensive, especially in a large network. In this paper, we take a different approach and explore an additional degree of freedom, namely, monitoring native links. We allow native link measurements, as well as end-to-end overlay measurements, in order to minimize the total cost of monitoring the network. We formulate an optimization problem that, when solved, identifies the optimal set of native and overlay links to monitor, and a feasible sequence of arithmetic operations to perform for inferring characteristics of the overlay links that are not monitored directly. We use simulations to investigate how various topological properties may affect the best monitoring strategy. We also conduct measurements over the PlanetLab network to quantify the accuracy of different monitoring strategies.

/pdf/multi-layer-monitoring-of-overlay-networks-2ylbhgstmu.pdf

Multi-layer Monitoring of Overlay Networks

IP over optical is being envisioned as one of the most attractive architectures for the new Internet. There have been various proposals in IETF and other international standards organizations regarding the interaction of IP routers and optical core networks. This paper describes the architectural alternatives for the integration of IP and DWDM networks using Multiprotocol Lambda Switching (MPLambdaS). The paper also addresses the issues of routing, signaling, control and survivability in an all-optical network.

https://www.cse.wustl.edu/~jain/papers/ftp/ipo_issues.pdf

Srini Seetharaman

Papers

MeasuRouting: A Framework for Routing Assisted Traffic Monitoring

GitFlow: flow revision management for software-defined networks

Method for routing-assisted traffic monitoring

Multi-layer Monitoring of Overlay Networks

IP over all-optical networks-issues