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The migration of DataCenters into Metropolitan Area Networks creates new challenges which include the need for rapid service provisioning and recovery and new, cost-effective, connectivity schemes. Here we propose and demonstrate a truly dynamic transportation platform tailored for a metro network. The novelty of the proposed architecture is that the dynamic data-plane exploits available commercial PON technology while the dynamic control-plane is SDN-enabled using OpenFlow/Netconf. The dynamic operation of the platform in several interesting scenarios is demonstrated on an experimental test-bed. [ABSTRACT FROM AUTHOR]

In this paper, we present a design for implementing network-based virtual Ethernet switches (NVESs) on top of a physical substrate consisting of a software-defined networking (SDN) network. An NVES has the same capability as a real Ethernet switch. A user makes a request to provision an NVES by specifying the number of ports and the maximum bandwidth for each port. The substrate network considered in this study is an Open Flow network. The entire network is controlled by an Open Flow controller. The controller is responsible for performing admission control, resource allocation, routing, address learning, and spanning tree protocol. To enhance the resource utilization of the substrate network, multipath routing is applied. Although using multipath routing can significantly improve bandwidth utilization, this approach results in out-of-order packet delivery and introduces additional error-control problems. To resolve these problems, we design a multipath agent to enhance the edge switch capability. The multipath agent is responsible for bandwidth metering, flow splitting, sequence number management, and packet reordering. We evaluated our virtual switches on top of a testbed network that includes not only commercial Open Flow switches but also a GPON-based virtual Open Flow switch. Multiple NVESs share the testbed network. The experimental results show that the user experience when using an NVES is identical to using a real Ethernet switch. In addition to the provision of guaranteed bandwidth for each NVES, traffic isolation among the NVESs is achieved. All NVESs are free of interference from others in the same network. [ABSTRACT FROM PUBLISHER]

Elastic optical networking (EON), with its flexible use of the optical spectrum, is a promising solution for future metro/core optical networking. For the deployment of EON in a real-operational scenario, the dynamic lightpath restoration, driven by an intelligent control plane, is a necessary network function. Dynamic restoration can restore network services automatically and, thus, greatly reduce the operational cost, compared with traditional manual or semistatic lightpath restoration strategies enabled by network operators via a network management system. To this end, in this paper, we present an OpenFlow-enabled dynamic lightpath restoration in elastic optical networks, detailing the restoration framework and algorithm, the failure isolation mechanism, and the proposed OpenFlow protocol extensions. We quantitatively present the restoration performance via control plane experimental tests on the Global Environment for Network Innovations testbed. [ABSTRACT FROM PUBLISHER]

Due to the emergence of cloud computing and various cloud services which are remote and geographically distributed, datacenters interconnected by optical networks have attracted much attention of network operators and service providers. With the purpose of supporting cloud services more effectively and efficiently, IT resources and interconnected network resources provisioning could be considered in an orchestrated way. In this paper, we present a datacenter resources integrated provisioning (DRIP) architecture utilizing coordinated virtualization of distributed datacenters and operator's multi-domain software defined optical networks. The DRIP architecture aims to accomplish IT resources and optical network resources integrated allocation. In order to investigate the feasibility and efficiency of the proposed architecture, two IT resources allocation strategies and two virtual network composition strategies are evaluated on our testbed. We perform experimental demonstration to evaluate the strategies’ performance in terms of three metrics, i.e., CPU utilization ratio of physical hosts, virtual network failure rate, and average latency. [ABSTRACT FROM PUBLISHER]

A multidomain optical transport network composed of heterogeneous optical transport technologies (e.g., flexi/fixed-grid optical circuit switching and optical packet switching) and control plane technologies (e.g., centralized OpenFlow or distributed GMPLS) does not naturally interoperate, and a network orchestration mechanism is required. A network orchestrator allows the composition of end-to-end network service provisioning across multidomain optical networks comprising different transport and control plane technologies. Software-defined networking (SDN) is a key technology to address this requirement, since the separation of control and data planes makes the SDN a suitable candidate for end-to-end provisioning service orchestration across multiple domains with heterogeneous control and transport technologies. This paper presents two different network orchestration's architectures based on the application-based network operations (ABNO) which is being defined by IETF based on standard building blocks. Then, we experimentally assesses in the international testbed of the STRAUSS project, an ABNO-based network orchestrator for end-to-end multi-layer (OPS and Flexi-grid OCS) and multidomain provisioning across heterogeneous control domains (SDN/OpenFlow and GMPLS/Stateful PCE) employing dynamic domain abstraction based on virtual node aggregation. [ABSTRACT FROM PUBLISHER]

This paper presents and experimentally demonstrates the generalized architecture of Openflow-controlled optical packet switching (OPS) network. Openflow control is enabled by introducing the Openflow/OPS agent into the OPS network, which realizes the Openflow protocol translation and message exchange between the Openflow control plane and the underlying OPS nodes. With software-defined networking (SDN) and Openflow technique, the complex control functions of the conventional OPS network can be offloaded into a centralized and flexible control plane, while promoted control and operations can be provided due to centralized coordination of network resources. Furthermore, a contention-aware routing/rerouting strategy as well as a fast network adjustment mechanism is proposed and demonstrated for the first time as advanced Openflow control to route traffic and handle the network dynamics. With centralized SDN/Openflow control, the OPS network has the potential to have better resource utilization and enhanced network resilience at lower cost and less node complexity. Our work will accelerate the development of both OPS and SDN evolution. [ABSTRACT FROM PUBLISHER]

Optical transport networks provide transport, multiplexing, routing, management, supervision, and survivability of optical channels. Within a flexible dense wavelength division multiplexing grid, the optical spectrum can be allocated in multiples of a width granularity, depending on the client signal rate and modulation format. A control plane (CP) can be used for efficient and dynamic provisioning and recovery of flexi-grid connections. Two main CP architectures coexist, with common functions like addressing, automatic topology discovery, network abstraction, path computation, and connection provisioning: a distributed generalized multiprotocol label switching CP (with optional path computation element, PCE path computation and instantiation/modification) and a CP based on software-defined networking, with a logically centralized controller and an open protocol, such as the OpenFlow protocol. Both architectures have their own strengths and weaknesses, and are being extended to address the new requirements associated with the aforementioned emerging optical technologies, such as flexible spectrum allocation, efficient corouted connection setup, and configuration of related optical parameters. However, new use cases such as remote data center interconnection highlight the need for multidomain service provisioning, and heterogeneous CP interworking, potentially requiring an overarching control. Different alternatives, with varying degrees of integration and flexibility, are available: straightforward approaches characterized by the adaptation of one control model to the other or more advanced interworking requiring the definition of common models (e.g., a subset of attributes for network elements) and of coordination and orchestration functions. This paper discusses the main relevant interworking architectures and presents a selected set of use cases and proof-of-concepts. [ABSTRACT FROM PUBLISHER]

Elastic optical networks (EONs) facilitate agile spectrum management in the optical layer. When coupling with software-defined networking, they function as software-defined EONs (SD-EONs) and provide service providers more freedom to customize their infrastructure dynamically. In this paper, we investigate how to overcome spectrum fragmentation in SD-EONs with OpenFlow-controlled online spectrum defragmentation (DF), and conduct system implementations to facilitate highly-efficient online DF. We first consider sequential DF, i.e., the scenario that involves a sequence of lightpath reconfigurations to progressively consolidate the spectrum utilization. We modify our previous DF algorithm to make sure that the reconfigurations can be performed in batches and the “make-before-break” scheme can be applied to all of them. The modified algorithm is implemented in an OpenFlow (OF) controller, and we design OF extensions to facilitate synchronous batch reconfiguration. Then, we further simplify the DF operations by designing and implementing parallel DF that can accomplish all the DF-related lightpath reconfigurations simultaneously. All these DF implementations are experimentally demonstrated in an SD-EON control plane testbed that consists of 14 stand-alone OF agents and one OF controller, which are all implemented based on high-performance Linux servers. The experimental results indicate that our OF-controlled online DF implementations perform well and can improve network performance in an efficient way. [ABSTRACT FROM PUBLISHER]

Adaptive flexi-grid optical networks should be able to autonomously decide where and when to dynamically setup, reoptimize, and release elastic optical connections, in reaction to network state changes. A stateful path computation element (PCE) is a key element for the introduction of dynamics and adaptation in generalized multiprotocol label switching (GMPLS)-based distributed control plane for flexi-grid DWDM networks (e.g., global concurrent reoptimization, defragmentation, or elastic inverse-multiplexing), as well as for enabling the standardized deployment of the GMPLS control plane in the software defined network control architecture. First, this paper provides an overview of passive and active stateful PCE architectures for GMPLS-enabled flexi-grid DWDM networks. A passive stateful PCE allows for improved path computation considering not only the network state (TED) but also the global connection state label switched paths database (LSPDB), in comparison with a (stateless) PCE. However, it does not have direct control (modification, rerouting) of path reservations stored in the LSPDB. The lack of control of these label switched paths (LSPs) may result in the suboptimal performance. To this end, an active stateful PCE allows for optimal path computation considering the LSPDB for the control of the state (e.g., increase of LSP bandwidth, LSP rerouting) of the stored LSPs. More recently, an active stateful PCE architecture has also been proposed that exposes the capability of setting up and releasing new LSPs. It is known as active stateful PCE with instantiation capabilities. This paper presents the first prototype implementation and experimental evaluation of an active stateful PCE with instantiation capabilities for the GMPLS-controlled flexi-grid DWDM network of the ADRENALINE testbed. [ABSTRACT FROM PUBLISHER]

Next generation optical networks will require high levels of flexibility both at the data and control planes, being able to fit rate, bandwidth, and optical reach requirements of different connections. Optical transmission should be able to support very high rates (e.g., 1 Tb/s) and to be distance adaptive while optimizing spectral efficiency (i.e., the information rate transmitted over a given bandwidth). Similarly, the control plane should be capable of performing effective routing and spectrum assignment as well as proper selection of the transmission parameters (e.g., modulation format) depending on the required optical reach. In this paper we present and demonstrate a software-defined super-channel transmission based on time frequency packing and on the proposed differentiated filter configuration (DFC). Time frequency packing is a technique able to achieve high spectral efficiency even with low-order modulation formats (e.g., quadrature phase-shift keying). It consists in sending pulses that overlap in time or frequency or both to achieve high spectral efficiency. Coding and detection are properly designed to account for the introduced inter-symbol and inter-carrier interference. We present a software defined network (SDN) controller that sets transmission parameters (e.g., code rate) both at the transmitter and the receiver side. In particular, at the transmitter side, a programmable encoder adding redundancy to the data is controlled by SDN. At the receiver side, the digital signal processing is set by SDN based on the selected transmission parameters (e.g., code rate). Thus, extensions to the OpenFlow architectures are presented to control super-channel transmission based on time frequency packing. Then, the SDN-based DFC is proposed. According to DFC, the passband of the filters traversed by the same connection can be configured to different values. Experiments including data and control planes are shown to demonstrate the feasibility of optical-reach-adaptive super-channel at 1 Tb/s controlled by extended OpenFlow. Then, the effectiveness of the proposed SDN-based DFC is demonstrated in a testbed with both wavelength selective switches and spectrum selective switches, where filters traversed by a connection requires different passband values. Extended OpenFlow messages for time frequency packing and supporting DFC have been captured and shown in the paper. [ABSTRACT FROM PUBLISHER]

We propose and discuss the extension of software-defined networking (SDN) and OpenFlow principles to optical access/aggregation networks for dynamic flex-grid wavelength circuit creation. The first experimental demonstration of an OpenFlow1.0-based flex-grid λ-flow architecture for dynamic 150 Mb/s per-cell 4 G Orthogonal Frequency Division Multiple Access (OFDMA) mobile backhaul (MBH) overlays onto 10 Gb/s passive optical networks (PON) without optical network unit (ONU)-side optical filtering, amplification, or coherent detection, over 20 km standard single mode fiber (SSMF) with a 1:64 passive split is also detailed. The proposed approach can be attractive for monetizing optical access/aggregation networks via on-demand support for high-speed, low latency, high quality of service (QoS) applications over legacy fiber infrastructure. [ABSTRACT FROM PUBLISHER]

In GMPLS-controlled optical networks, the utilization of source-based path computation has some limitations, especially in large networks with stringent constraints (e.g., optical impairments) or in multilayer and multidomain networks, which leads to suboptimal routing solutions. The path computation eElement (PCE) can mitigate some weaknesses of GMPLS-controlled optical networks. The main idea behind the PCE is to decouple the path computation function from the GMPLS controllers into a dedicated entity with an open and well-defined interface and protocol. A (stateless) PCE is capable of computing a network path or route based on a network graph (i.e., the traffic engineering database-TED) and applying computational constraints. First, we present an overview of the PCE architecture and its communication protocol (PCEP). Then, we present in detail the considered source-routing shortcomings in GMPLS-controlled networks, namely, impairment-aware path computation, multidomain path computation and multilayer path computation, as well as the different PCE-based solutions that have been proposed to overcome each one of these problems. However, PCE-based computation also presents some limitations that lead to an increase in the path computation blocking or to suboptimal path computations. The stateful PCE overcomes the limitations of the stateless PCE, such as the outdated TED, the lack of global LSP state (i.e., set of computed paths and reserved resources in use in the network), and the lack of control of path reservations. A passive stateful PCE allows optimal path computation and increased path computation success, considering both the network state (TED) and the Label Switched Paths (LSP) state (LSP Database-LSPDB). Additionally, an active stateful PCE can modify existing LSPs (i.e., connections), and optionally, setup and/or release existing LSPs. Finally, the formal decoupling of the path computation allows more flexibility in the deployment of PCEs in other control paradigms outside their original scope (MPLS/GMPLS). In this sense, we provide an overview of three PCE deployment models in the software defined network (SDN) control architecture. [ABSTRACT FROM PUBLISHER]

Software defined networking and OpenFlow, which allow operators to control the network using software running on a network operating system within an external controller, provide the maximum flexibility for the operator to control a network, and match the carrier's preferences given its centralized architecture, simplicity, and manageability. In this paper, we report a field trial of an OpenFlow-based unified control plane (UCP) for multilayer multigranularity optical switching networks, verifying its overall feasibility and efficiency, and quantitatively evaluating the latencies for end-to-end path creation and restoration. To the best of our knowledge, the field trial of an OpenFlow-based UCP for optical networks is a world first. [ABSTRACT FROM PUBLISHER]