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 Transmission Control Protocol.

Network management is challenging. To operate, maintain, and secure a communication network, network operators must grapple with low-level vendor-specific configuration to implement complex high-level network policies. Despite many previous proposals to make networks easier to manage, many solutions to network management problems amount to stop-gap solutions because of the difficulty of changing the underlying infrastructure. The rigidity of the underlying infrastructure presents few possibilities for innovation or improvement, since network devices have generally been closed, proprietary, and vertically integrated. A new paradigm in networking, software defined networking (SDN), advocates separating the data plane and the control plane, making network switches in the data plane simple packet forwarding devices and leaving a logically centralized software program to control the behavior of the entire network. SDN introduces new possibilities for network management and configuration methods. In this article, we identify problems with the current state-of-the-art network configuration and management mechanisms and introduce mechanisms to improve various aspects of network management. We focus on three problems in network management: enabling frequent changes to network conditions and state, providing support for network configuration in a highlevel language, and providing better visibility and control over tasks for performing network diagnosis and troubleshooting. The technologies we describe enable network operators to implement a wide range of network policies in a high-level policy language and easily determine sources of performance problems. In addition to the systems themselves, we describe various prototype deployments in campus and home networks that demonstrate how SDN can improve common network management tasks.

Improving network management with software defined networking

Multipath TCP (MPTCP) adds the capability of using multiple paths to a
regular TCP session. Even though it is designed to be totally backward
compatible to applications, the data transport differs compared to
regular TCP, and there are several additional degrees of freedom that
applications may wish to exploit. This document summarizes the impact
that MPTCP may have on applications, such as changes in performance.
Furthermore, it discusses compatibility issues of MPTCP in combination
with non-MPTCP-aware applications. Finally, the document describes a
basic application interface that is a simple extension of TCP's
interface for MPTCP-aware applications.

/pdf/multipath-tcp-mptcp-application-interface-considerations-51zxvbh6vp.pdf

Multipath TCP (MPTCP) Application Interface Considerations

We consider a system of compute and storage resources geographically distributed over a large number of locations connected via a wide-area network. By distributing the resources, latency to users can be decreased, bandwidth costs reduced and availablility increased. The challenge is to distribute services with varying characteristics among the data centers optimally. Some services are very latency sensitive, others need vast amounts of storage, and yet others are computationally complex but do not require hard deadlines on execution. We propose efficient algorithms for the placement of services to get the maximum benefit from a distributed cloud systems. The algorithms need input on the status of the network, compute resources and data resources, which are matched to application requirements.This demonstration shows how a network-aware cloud can combine all three resource types - computation, storage, and network connectivity - in distributed cloud environments. Our dynamic service placement algorithm monitors the network and data center resources in real-time. Our prototype uses the information gathered to place or migrate services to provide the best user experience for a service.

/pdf/network-aware-service-placement-in-a-distributed-cloud-1328mrb5pb.pdf

Network-aware service placement in a distributed cloud environment

This document describes some of the open problems in Internet
congestion control that are known today. This includes several new
challenges that are becoming important as the network grows, as well
as some issues that have been known for many years. These challenges
are generally considered to be open research topics that may require
more study or application of innovative techniques before Internet-
scale solutions can be confidently engineered and deployed. This
document is not an Internet Standards Track specification; it is
published for informational purposes.

Open Research Issues in Internet Congestion Control

Many signaling protocols in IP networks need a protection against message loss, but they do not require a strict in-sequence data delivery. Since TCP provides reliable in-order transport, end-to-end delays may be unnecessarily increased due to head-of-line blocking. An alternative transport protocol is SCTP, which is optimized for signaling applications and provides mechanisms for reliable, partial-ordered or unordered message delivery. In this paper, we quantify the impact of head-of-line blocking on the response time of transaction-based signaling applications. In order to mitigate this problem, we compare dif- ferent solutions based on TCP and SCTP. Both a new analytical model and measurements on state-of-the-art operating systems show to which extend SCTP can improve transport delays by leveraging transmission over multiple parallel streams or using unordered data delivery. Our analysis reveals that using one or multiple parallel TCP connections can result in much higher end-to-end delays, even for moderate packet loss probabilities. We also observe significant differences in the TCP performance of different operating systems.

Head-of-line Blocking in TCP and SCTP: Analysis and Measurements

Many signaling protocols in IP networks need a protection against message loss, but they do not require a strict in-sequence data delivery. Since TCP provides reliable in-order transport, end-to-end delays may be unnecessarily increased due to head-of-line blocking. An alternative transport protocol is SCTP, which is optimized for signaling applications and provides mechanisms for reliable, partial-ordered or unordered message delivery. In this paper, we quantify the impact of head-of-line blocking on the response time of transaction-based signaling applications. In order to mitigate this problem, we compare different solutions based on TCP and SCTP. Both a new analytical model and measurements on state-of-the-art operating systems show to which extend SCTP can improve transport delays by leveraging transmission over multiple parallel streams or using unordered data delivery. Our analysis reveals that using one or multiple parallel TCP connections can result in much higher end-to-end delays, even for moderate packet loss probabilities. We also observe significant differences in the TCP performance of different operating systems.

Michael Scharf

Papers

Multipath TCP (MPTCP) Application Interface Considerations

Network-aware service placement in a distributed cloud environment

Open Research Issues in Internet Congestion Control

Head-of-line Blocking in TCP and SCTP: Analysis and Measurements

NXG03-5: Head-of-line Blocking in TCP and SCTP: Analysis and Measurements