239 research outputs found
A survey on OFDM-based elastic core optical networking
Orthogonal frequency-division multiplexing (OFDM) is a modulation technology that has been widely adopted in many new and emerging broadband wireless and wireline communication systems. Due to its capability to transmit a high-speed data stream using multiple spectral-overlapped lower-speed subcarriers, OFDM technology offers superior advantages of high spectrum efficiency, robustness against inter-carrier and inter-symbol interference, adaptability to server channel conditions, etc. In recent years, there have been intensive studies on optical OFDM (O-OFDM) transmission technologies, and it is considered a promising technology for future ultra-high-speed optical transmission. Based on O-OFDM technology, a novel elastic optical network architecture with immense flexibility and scalability in spectrum allocation and data rate accommodation could be built to support diverse services and the rapid growth of Internet traffic in the future. In this paper, we present a comprehensive survey on OFDM-based elastic optical network technologies, including basic principles of OFDM, O-OFDM technologies, the architectures of OFDM-based elastic core optical networks, and related key enabling technologies. The main advantages and issues of OFDM-based elastic core optical networks that are under research are also discussed
Resilience options for provisioning anycast cloud services with virtual optical networks
Optical networks are crucial to support increasingly demanding cloud services. Delivering the requested quality of services (in particular latency) is key to successfully provisioning end-to-end services in clouds. Therefore, as for traditional optical network services, it is of utter importance to guarantee that clouds are resilient to any failure of either network infrastructure (links and/or nodes) or data centers. A crucial concept in establishing cloud services is that of network virtualization: the physical infrastructure is logically partitioned in separate virtual networks. To guarantee end-to-end resilience for cloud services in such a set-up, we need to simultaneously route the services and map the virtual network, in such a way that an alternate routing in case of physical resource failures is always available. Note that combined control of the network and data center resources is exploited, and the anycast routing concept applies: we can choose the data center to provide server resources requested by the customer to optimize resource usage and/or resiliency. This paper investigates the design of scalable optimization models to perform the virtual network mapping resiliently. We compare various resilience options, and analyze their compromise between bandwidth requirements and resiliency quality
Virtualization of elastic optical networks and regenerators with traffic grooming
An elastic optical network (EON) plays an important role in transport technology for virtualization of networks. A key aspect of EONs is to establish lightpaths (virtual links) with exactly the amount of spectrum that is needed and with the possibility of grooming, the process of grouping many small traffic flows into larger units, creating a super-lightpath. Grooming eliminates the need for many guard bands between lightpaths and also saves transceivers; however, it often leads to the need to perform optical–electrical–optical conversions to multiple-data-rate optical signals at intermediate nodes. The aim of this paper is to provide a mixed-integer linear programming (MILP) formulation, as well as heuristic and meta-heuristic approaches, for the design of multiple virtual optical networks (VONs) in an elastic optical substrate network with bandwidth-variable lightpaths, modulation format constraints, and virtual elastic regenerator placement. Traffic grooming is allowed inside each VON, and a distance-adaptive modulation format technique is employed to guarantee efficiency in terms of bandwidth for a physical substrate, subject to several virtual topologies. A reduced MILP formulation without grooming capability is also proposed for comparison. The complete MILP formulation jointly solves the virtual topology design, regenerator placement, and grooming problems, as well as the routing, modulation, and spectrum assignment (RMSA) problem. The reduced MILP formulation, heuristics, and meta-heuristic, on the other hand, separate the virtual topology design problem from the RMSA problem. It is shown that the grooming approach can provide good results, since it solves the problem for a complete design when compared to the approach without grooming. Furthermore, heuristic solutions for large networks are proposed, which present good performance (in terms of saving spectrum) for the design with large instances
Experimental SDN Control Solutions for Automatic Operations and Management of 5G Services in a Fixed Mobile Converged Packet-Optical Network
5G networks will impose network operators to
accommodate services demanding heterogeneous and stringent
requirements in terms of increased bandwidth, reduced latency,
higher availability, etc. as well as enabling emerging capabilities
such as slicing. Operators will be then forced to make notable
investments in their infrastructure but the revenue is not
envisaged to be proportional. Thereby, operators are seeking for
more cost-effective solutions to keep their competitiveness. An
appealing solution is to integrate all (broadband) services
including both fixed and mobile in a convergent way. This is
referred to as Fixed Mobile Convergence (FMC). FMC allows
seamlessly serving any kind of access service over the same
network infrastructure (access, aggregation and core) and relying
on common set of control and operation functions. To this end,
FMC leverages the benefits provided by Software Defined
Networking (SDN) and Network Function Virtualization (NFV).
First, we discuss some of the explored FMC solutions and
technologies, from both structural and functional perspectives
Next, focusing on a Multi-Layer (Packet and Optical) Aggregation
Network, we report two implemented and experimentally
validated SDN/NFV orchestration architectures providing feasibleThis work has been partially funded by the Spanish Ministry
MINECO projects DESTELLO (TEC2015-69256-R) and 5G-REFINE
(TEC2017-88373-R), and the EU H2020 5G TRANSFORMER project
(grant no. 761536)
Latency-aware resource orchestration in SDN-based packet over optical flexi-grid transport networks
In the upcoming 5G networks and following
the emerging Software Defined Network/Network
Function Virtualization (SDN/NFV) paradigm, demanded
services will be composed of a number of
virtual network functions that may be spread across
the whole transport infrastructure and allocated in
distributed Data Centers (DCs). These services will
impose stringent requirements such as bandwidth
and end-to-end latency that the transport network
will need to fulfill. In this paper, we present an orchestration
system devised to select and allocate virtual
resources in distributed DCs connected through a
multi-layer (Packet over flexi-grid optical) network.
Three different on-line orchestration algorithms are
conceived to accommodate the incoming requests by
satisfying computing, bandwidth and end-to-end latency
constraints, setting up multi-layer connections.
We addressed end-to-end latency requirements by
considering both network (due to propagation delay)
and processing delay components. The proposed algorithms
have been extensively evaluated and assessed
(via a number of figures of merit) through experimental
tests carried out in a Packet over Optical
Flexi-Grid Network available in the ADRENALINE
testbed with emulated DCs connected to it.This work has been partially funded by the EC H2020 5GTransformer Project (grant No. 761536)
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