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.

Today's data networks are surprisingly fragile and difficult to manage. We argue that the root of these problems lies in the complexity of the control and management planes--the software and protocols coordinating network elements--and particularly the way the decision logic and the distributed-systems issues are inexorably intertwined. We advocate a complete refactoring of the functionality and propose three key principles--network-level objectives, network-wide views, and direct control--that we believe should underlie a new architecture. Following these principles, we identify an extreme design point that we call "4D," after the architecture's four planes: decision, dissemination, discovery, and data. The 4D architecture completely separates an AS's decision logic from pro-tocols that govern the interaction among network elements. The AS-level objectives are specified in the decision plane, and en-forced through direct configuration of the state that drives how the data plane forwards packets. In the 4D architecture, the routers and switches simply forward packets at the behest of the decision plane, and collect measurement data to aid the decision plane in controlling the network. Although 4D would involve substantial changes to today's control and management planes, the format of data packets does not need to change; this eases the deployment path for the 4D architecture, while still enabling substantial innovation in network control and management. We hope that exploring an extreme design point will help focus the attention of the research and industrial communities on this crucially important and intellectually challenging area.

/pdf/a-clean-slate-4d-approach-to-network-control-and-management-2ks1hufhx0.pdf

A clean slate 4D approach to network control and management

In Named Data Networking (NDN) architecture, packets carry data names rather than source or destination addresses. This change of paradigm leads to a new data plane: data consumers send out Interest packets, routers forward them and maintain the state of pending Interests, which is used to guide Data packets back to the consumers. NDN routers' forwarding process is able to detect network problems by observing the two-way traffic of Interest and Data packets, and explore multiple alternative paths without loops. This is in sharp contrast to today's IP forwarding process which follows a single path chosen by the routing process, with no adaptability of its own. In this paper we outline the design of NDN's adaptive forwarding, articulate its potential benefits, and identify open research issues.

/pdf/adaptive-forwarding-in-named-data-networking-3sius9lskr.pdf

Adaptive forwarding in named data networking

This talk introduces GENI, the National Science Foundation's ambitious plan to build a national infrastructure suite to enable research into Network Science and Engineering for future global communications networks. GENI has just entered Spiral 1, a new stage in its development. Early prototyping is now beginning, which will offer illumination into its construction plans and research potential. The first round of software, hardware, and trial facilities are now being built by academic and industrial research teams. This talk presents current plans for GENI, but leaves plenty of time for discussion and brain-storming, both for the eventual infrastructure suite and for prototypes that will be built in the coming year.

GENI - global environment for network innovations

This document defines RSVP-TE extensions to establish backup label-
switched path (LSP) tunnels for local repair of LSP tunnels. These
mechanisms enable the re-direction of traffic onto backup LSP tunnels
in 10s of milliseconds, in the event of a failure. Two methods are
defined here. The one-to-one backup method creates detour LSPs for
each protected LSP at each potential point of local repair. The
facility backup method creates a bypass tunnel to protect a potential
failure point; by taking advantage of MPLS label stacking, this bypass
tunnel can protect a set of LSPs that have similar backup constraints.
Both methods can be used to protect links and nodes during network
failure. The described behavior and extensions to RSVP allow nodes to
implement either method or both and to interoperate in a mixed
network. [STANDARDS-TRACK]

Fast Reroute Extensions to RSVP-TE for LSP Tunnels

This document describes the use of loop-free alternates to provide
local protection for unicast traffic in pure IP and MPLS/LDP networks
in the event of a single failure, whether link, node or shared risk
link group (SRLG). The goal of this technology is to reduce the packet
loss that happens while routers converge after a topology change due
to a failure. Rapid failure repair is achieved through use of
precalculated backup next-hops that are loop-free and safe to use
until the distributed network convergence process completes. This
simple approach does not require any support from other routers. The
extent to which this goal can be met by this specification is
dependent on the topology of the network.

Basic Specification for IP Fast Reroute: Loop-Free Alternates

A centralized controller provides dynamic end-to-end network path setup across multiple network layers. In particular, the centralized controller manages end-to-end network path setup that provisions a path at both the transport network layer (e.g., optical) and the service network layer (e.g., IP/MPLS). The centralized controller performs path computation for an optical path at the transport network layer and for a path at the service network layer that transports network traffic on the underlying optical transport path, based on information obtained by the centralized controller from the underlying network components at both layers.

Dynamic end-to-end network path setup across multiple network layers

Network traffic is sent via alternate paths in cases of network link or node failure. An alternate node responds to U-Turn traffic from a primary neighbor to select a further alternate. An algorithm for determining the alternate paths is provided to select loop-free neighbors.

Selecting alternate paths for network destinations

Routers balance network traffic among multiple paths through a network according to an amount of bandwidth that can be sent on an outgoing interface computed for each of the paths. For example, a router receives a link bandwidth for network links that are positioned between the first router and a second router of the network, and selects a plurality of forwarding paths from the first router to the second router. Upon determining that one of the network links is shared by multiple of the plurality of forwarding paths, the router computes a path bandwidth for each of the plurality of forwarding paths so as to account for splitting of link bandwidth of the shared network link across the multiple forwarding paths that share the network link. The router assigns packet flows to the forwarding paths based at least on the computed amount of bandwidth for each of the forwarding paths.

Alia Atlas

Papers

Fast Reroute Extensions to RSVP-TE for LSP Tunnels

Basic Specification for IP Fast Reroute: Loop-Free Alternates

Dynamic end-to-end network path setup across multiple network layers

Selecting alternate paths for network destinations

Path weighted equal-cost multipath