https://www.cba.upc.edu/downloads/category/11-articles?download=355:[ARTICLE]A_survey_on_physical_layer_impairments_aware_routing_and_wavelength_assignment_algorithms_in_optical_networks.pdf

A survey on physical layer impairments aware routing and wavelength assignment algorithms in optical networks

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.

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A Survey on the Contributions of Software-Defined Networking to Traffic Engineering

Quality of Service-enabled applications and services rely on Traffic Engineering-based (TE) Label Switched Paths (LSP) established in core networks and controlled by the GMPLS control plane. Path computation process is crucial to achieve the desired TE objective. Its actual effectiveness depends on a number of factors. Mechanisms utilized to update topology and TE information, as well as the latency between path computation and resource reservation, which is typically distributed, may affect path computation efficiency. Moreover, TE visibility is limited in many network scenarios, such as multi-layer, multi-domain and multi-carrier networks, and it may negatively impact resource utilization. The Internet Engineering Task Force (IETF) has promoted the Path Computation Element (PCE) architecture, proposing a dedicated network entity devoted to path computation process. The PCE represents a flexible instrument to overcome visibility and distributed provisioning inefficiencies. Communications between path computation clients (PCC) and PCEs, realized through the PCE Protocol (PCEP), also enable inter-PCE communications offering an attractive way to perform TE-based path computation among cooperating PCEs in multi-layer/domain scenarios, while preserving scalability and confidentiality. This survey presents the state-of-the-art on the PCE architecture for GMPLS-controlled networks carried out by research and standardization community. In this work, packet (i.e., MPLS-TE and MPLS-TP) and wavelength/spectrum (i.e., WSON and SSON) switching capabilities are the considered technological platforms, in which the PCE is shown to achieve a number of evident benefits.

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A Survey on the Path Computation Element (PCE) Architecture

Core optical networks using reconfigurable optical switches and tunable lasers appear to be on the road towards widespread deployment and could evolve to all-optical mesh networks in the coming future. Considering the impact of physical layer impairments in the planning and operation of all-optical (and translucent) networks is the main focus of the Dynamic Impairment Constraint Optical Networking (DICONET) project. The impairment aware network planning and operation tool (NPOT) is the main outcome of DICONET project, which is explained in detail in this paper. The key building blocks of the NPOT, consisting of network description repositories, the physical layer performance evaluator, the impairment aware routing and wavelength assignment engines, the component placement modules, failure handling, and the integration of NPOT in the control plane are the main contributions of this study. Besides, the experimental result of DICONET proposal for centralized and distributed control plane integration schemes and the performance of the failure handling in terms of restoration time is presented in this study.

/pdf/experimental-demonstration-of-an-impairment-aware-network-4p3njkrfqz.pdf

Experimental Demonstration of an Impairment Aware Network Planning and Operation Tool for Transparent/Translucent Optical Networks

Flexible optical networks, based on bandwidth-variable optical cross-connects (BV-OXCs) and novel flexible transponders, are expected to significantly improve the overall spectrum efficiency with respect to traditional networks where fixed frequency spacing is applied. Flexible optical networks will exploit the BV-OXC capability to dynamically configure the reserved bandwidth as a set of frequency slots. In addition, flexible transponders will be employed to dynamically configure transmission parameters, such as bit-rate and modulation format. To enable these new configuration capabilities, network operation enhancements need to be efficiently introduced and investigated. In this study, we focus for the first time on the Path Computation Element (PCE) architecture for flexible optical networks. PCE architecture and PCE communication protocol are enhanced to maximize the spectral efficiency and to provide indications also on the specific transmission parameters to configure. Experimental demonstration is provided through two different experiments, successfully showing the PCE capability to trigger dynamic rerouting with bit-rate or modulation format adaptation. In particular, the experiments demonstrate, in a real testbed, dynamic frequency slot assignment and format adaptation from DP-16QAM to DP-QPSK at 100 Gb/s, and bit-rate adaptation at DP-16QAM from 200 Gb/s to 100 Gb/s.

Demonstration of Flexible Optical Network Based on Path Computation Element

Optical PCE and its interwork with the NMS were investigated for planning and operation of optical transparent networks. We successfully verified effective and fast optical-path computation taking into account the physical impairments and wavelength continuity.

Optical Path Computation Element interworking with Network Management System for Transparent Mesh Networks

A multi-layer NMS was successfully developed to manage the optical network and the MPLS network. The integrated network-planning tool could appropriately provide the optimized routes for a new LSP and all the existing LSPs.

Multi-layer Network Management System integrated with a Network Planning Tool for IP/Optical integrated network

This paper proposes an operation management system to analyze operating workflows as preliminary step for the continual improvement of them. To provide highly dependable and cost effective services, telecom operators must decrease human errors and operational costs. It is common for the operators to conduct operating procedures by following predefined operational workflows. However, it is difficult to predefine the workflow to cover all the operational conditions, and thus the operator's personal decisions are involved in the operations. In order to minimize the human errors, first, actual operating procedures need to be quantitatively assessed, and second, the result needs to be reflected to the workflows for the optimization. The Operation Record Analysis System (OPERAS) is proposed to analyze the operating workflow for the continual improvement of them by introducing the aforementioned optimization. The algorithm and system design of the OPERAS are described, and the implemented OPERAS is demonstrated for proof of concept. Throughout the demonstration in a scenario assuming network equipment installation, the basic system capabilities to analyze operating workflows such as management of workflows, recording operating procedures, and outputting operating statistics are shown.

OPERAS: Operation record analysis system for continual improvement of operating workflows

B-14-14 Proposal of the Architecture of a QoS Assured Network by Cooperating between IP Flow Control and MPLS DiffServ-TE

This paper proposes a network architecture to achieve a QoS assured network, which is composed of two QoS control technologies such as IP flow control and MPLS DiffServ-TE. IP flow control technology is utilized to treat IP packets as an IP flow distinguished by source and destination IP addresses, ports, protocol and priority and to apply the CAC function on the per-flow basis. MPLS DiffServ-TE is also used to accommodate multiple IP flows along the LSP via a bandwidth guarantee with certain service classes. By using the network testbed, we confirmed some of functions in our proposed architecture of the QoS assured network worked properly following the CAC capability of flow state routing and LSP-based bandwidth guarantee of MPLS DiffServ-TE. Multiple IP flows can be appropriately conveyed over the assigned LSP. Moreover, we verified the operation of the prototype NMS to monitor IP flows, LSPs and the inclusion relationship between them. And we also derived a policy to set the bandwidth for CAC at the edge router for effective utilization of bandwidth.

Shuntaro Kashihara

Papers

Optical Path Computation Element interworking with Network Management System for Transparent Mesh Networks

Multi-layer Network Management System integrated with a Network Planning Tool for IP/Optical integrated network

OPERAS: Operation record analysis system for continual improvement of operating workflows

B-14-14 Proposal of the Architecture of a QoS Assured Network by Cooperating between IP Flow Control and MPLS DiffServ-TE

Proposal of the Architecture of a QoS Assured Network by Cooperating between IP Flow Control and MPLS DiffServ-TE