1,463 research outputs found
A Survey on the Contributions of Software-Defined Networking to Traffic Engineering
Since the appearance of OpenFlow back in 2008, software-defined networking (SDN) has gained momentum. Although there are some discrepancies between the standards developing organizations working with SDN about what SDN is and how it is defined, they all outline traffic engineering (TE) as a key application. One of the most common objectives of TE is the congestion minimization, where techniques such as traffic splitting among multiple paths or advanced reservation systems are used. In such a scenario, this manuscript surveys the role of a comprehensive list of SDN protocols in TE solutions, in order to assess how these protocols can benefit TE. The SDN protocols have been categorized using the SDN architecture proposed by the open networking foundation, which differentiates among data-controller plane interfaces, application-controller plane interfaces, and management interfaces, in order to state how the interface type in which they operate influences TE. In addition, the impact of the SDN protocols on TE has been evaluated by comparing them with the path computation element (PCE)-based architecture. The PCE-based architecture has been selected to measure the impact of SDN on TE because it is the most novel TE architecture until the date, and because it already defines a set of metrics to measure the performance of TE solutions. We conclude that using the three types of interfaces simultaneously will result in more powerful and enhanced TE solutions, since they benefit TE in complementary ways.European Commission through the Horizon 2020 Research and Innovation Programme (GN4) under Grant 691567
Spanish Ministry of Economy and Competitiveness under the Secure Deployment of Services Over SDN and NFV-based Networks Project S&NSEC under Grant TEC2013-47960-C4-3-
Mathematical aspects of scattering amplitudes
In these lectures we discuss some of the mathematical structures that appear
when computing multi-loop Feynman integrals. We focus on a specific class of
special functions, the so-called multiple polylogarithms, and discuss introduce
their Hopf algebra structure. We show how these mathematical concepts are
useful in physics by illustrating on several examples how these algebraic
structures are useful to perform analytic computations of loop integrals, in
particular to derive functional equations among polylogarithms.Comment: 58 pages. Lectures presented at TASI 201
Quality of Service over Specific Link Layers: state of the art report
The Integrated Services concept is proposed as an enhancement to the current Internet architecture, to provide a better Quality of Service (QoS) than that provided by the traditional Best-Effort service. The features of the Integrated Services are explained in this report. To support Integrated Services, certain requirements are posed on the underlying link layer. These requirements are studied by the Integrated Services over Specific Link Layers (ISSLL) IETF working group. The status of this ongoing research is reported in this document. To be more specific, the solutions to provide Integrated Services over ATM, IEEE 802 LAN technologies and low-bitrate links are evaluated in detail. The ISSLL working group has not yet studied the requirements, that are posed on the underlying link layer, when this link layer is wireless. Therefore, this state of the art report is extended with an identification of the requirements that are posed on the underlying wireless link, to provide differentiated Quality of Service
Bootstrapping Real-world Deployment of Future Internet Architectures
The past decade has seen many proposals for future Internet architectures.
Most of these proposals require substantial changes to the current networking
infrastructure and end-user devices, resulting in a failure to move from theory
to real-world deployment. This paper describes one possible strategy for
bootstrapping the initial deployment of future Internet architectures by
focusing on providing high availability as an incentive for early adopters.
Through large-scale simulation and real-world implementation, we show that with
only a small number of adopting ISPs, customers can obtain high availability
guarantees. We discuss design, implementation, and evaluation of an
availability device that allows customers to bridge into the future Internet
architecture without modifications to their existing infrastructure
Optimized Design of Survivable MPLS over Optical Transport Networks. Optical Switching and Networking
In this paper we study different options for the survivability implementation
in MPLS over Optical Transport Networks in terms of network resource usage and
configuration cost. We investigate two approaches to the survivability
deployment: single layer and multilayer survivability and present various
methods for spare capacity allocation (SCA) to reroute disrupted traffic. The
comparative analysis shows the influence of the traffic granularity on the
survivability cost: for high bandwidth LSPs, close to the optical channel
capacity, the multilayer survivability outperforms the single layer one,
whereas for low bandwidth LSPs the single layer survivability is more
cost-efficient. For the multilayer survivability we demonstrate that by mapping
efficiently the spare capacity of the MPLS layer onto the resources of the
optical layer one can achieve up to 22% savings in the total configuration cost
and up to 37% in the optical layer cost. Further savings (up to 9 %) in the
wavelength use can be obtained with the integrated approach to network
configuration over the sequential one, however, at the increase in the
optimization problem complexity. These results are based on a cost model with
actual technology pricing and were obtained for networks targeted to a
nationwide coverage
Mobile MPLS-TP - Support the mobility of terminal devices
MPLS architecture for transport networks play the significant role in the development of next generation networks, in particular with regard to the guarantee of continuity of communications "end-to-end" through a variety of heterogeneous segments of the telecommunications network. The article presents the concept of Mobile MPLS-TP with the use of OAM channels to support the mobility of users and optimize "Handoff" procedure in a hierarchical network topology
Ethernet - a survey on its fields of application
During the last decades, Ethernet progressively became the most widely used local area networking (LAN) technology. Apart from LAN installations, Ethernet became also attractive for many other fields of application, ranging from industry to avionics, telecommunication, and multimedia. The expanded application of this technology is mainly due to its significant assets like reduced cost, backward-compatibility, flexibility, and expandability. However, this new trend raises some problems concerning the services of the protocol and the requirements for each application. Therefore, specific adaptations prove essential to integrate this communication technology in each field of application. Our primary objective is to show how Ethernet has been enhanced to comply with the specific requirements of several application fields, particularly in transport, embedded and multimedia contexts. The paper first describes the common Ethernet LAN technology and highlights its main features. It reviews the most important specific Ethernet versions with respect to each application fieldâs requirements. Finally, we compare these different fields of application and we particularly focus on the fundamental concepts and the quality of service capabilities of each proposal
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Integration of unidirectional technologies into wireless back-haul architecture
This thesis was submitted for the degree of Docter of Philosophy and awarded by Brunel University.Back-haul infrastructures of today's wireless operators must support the triple-play services demanded by the market or regulatory bodies. To cope with increasing capacity demand, the EU FP7 project CARMEN has developed a cost-effective heterogeneous
multi-radio wireless back-haul architecture, which may also leverage the native multicast
capabilities of broadcast technologies such as DVB-T to off-load high-bandwidth broadcast
content delivery. However, the integration of such unidirectional technologies into a packet-switched architecture requires careful considerations. The contribution of this thesis is the investigation, design and evaluation of protocols and mechanisms facilitating the integration of such unidirectional technologies into the wireless
back-haul architecture so that they can be configured and utilized by the spectrum and
capacity optimization modules. This integration mainly concerns the control plane and, in particular, the aspects related to resource and capability descriptions, neighborhood, link and Multi Protocol Label Switching (MPLS) Label-Switched Path (LSP) monitoring, unicast and multicast LSP signalling as well as topology forming and maintenance. During the course of this study we have analyzed the problem space, proposed solutions to the resulting research questions and evaluated our approach. Our results show that the now Unidirectional Technology (UDT)-aware architecture can readily consider
Unidirectional Technologies (UDTs) to distribute, for example, broadcast content
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