Yajie Li

Demonstration of multi-domain spectrum defragmentation with minimum controller-participation degree in elastic optical networks

Spectrum defragmentation in elastic optical networks can be considered to conduct rearrangement of the deployed lightpaths, which can achieve some optimization objectives including lower blocking probability, higher spectrum utilization, minimum connection disruption and so on. The emergence of software-defined networks provides an effective way to implement spectrum defragmentation in control plane. With restricted domain visibility in multi-domain or multivendor scenario, the complex procedure of multi-controller cooperation is inevitable during the multi-domain lightpath provisioning. In this paper, we first introduce the concept of controller-participation degree (CPD) to quantize the times local controllers are involved in multi-domain defragmentation. Then we propose a novel multi-domain defragmentation (MD-DF) scheme with minimum controller-participation degree, which can be categorized as reactive strategy. Based on whether the potential blocked lightpath goes through inter-domain links, the MD-DF scheme covers intra-domain scenario and cross-domain scenario. The proposed scheme is implemented in OpenDayLight (ODL) controller and experimental results validate the overall feasibility. Meanwhile, simulation results indicate that the improved blocking performance is achieved with the MD-DF scheme.

Network function virtualization in software defined optical transport networks

Network function virtualization (NFV) enabled software defined optical transport networks are first designed to implement the virtualization of control and node function, and virtualization solution is demonstrated to verify the overall feasibility and efficiency.

A novel integratable optical analog-to-digital converter based on cascaded step-size MMI

A novel phase-shifted optical analog-to-digital converter using cascaded step-size MMI as quantization module is demonstrated. The cascaded MMI on SOI has a compact footprint of 7.5×100 μm2 and ultra-low insertion loss of 0.2dB.

Data analysis-based autonomic bandwidth adjustment in software defined multi-vendor optical transport networks

Network operators generally provide dedicated lightpaths for customers to meet the demand for high-quality transmission. Considering the variation of traffic load, customers usually rent peak bandwidth that exceeds the practical average traffic requirement. In this case, bandwidth provisioning is unmetered and customers have to pay according to peak bandwidth. Supposing that network operators could keep track of traffic load and allocate bandwidth dynamically, bandwidth can be provided as a metered service and customers would pay for the bandwidth that they actually use. To achieve cost-effective bandwidth provisioning, this paper proposes an autonomic bandwidth adjustment scheme based on data analysis of traffic load. The scheme is implemented in a software defined networking (SDN) controller and is demonstrated in the field trial of multi-vendor optical transport networks. The field trial shows that the proposed scheme can track traffic load and realize autonomic bandwidth adjustment. In addition, a simulation experiment is conducted to evaluate the performance of the proposed scheme. We also investigate the impact of different parameters on autonomic bandwidth adjustment. Simulation results show that the step size and adjustment period have significant influences on bandwidth savings and packet loss. A small value of step size and adjustment period can bring more benefits by tracking traffic variation with high accuracy. For network operators, the scheme can serve as technical support of realizing bandwidth as metered service in the future.

Experimental demonstration of datacenter networking based on software defined optical networks with flexible ROADM

Computing and storage resources are two kinds of important resources for cloud computing, which are provided by different datacenters distributed at different positions. Then, datacenter networking is necessary for high efficient resource provisioning. Flexi-grid optical network is considered as a promising technology for datacenter networking because of its high spectrum efficiency and fine switching granularities. Meanwhile, as a centralized control model, the software defined networking (SDN) enabled by OpenFlow protocol can provide high flexibility for the networks and make a unified control over various resources for the joint optimization of datacenter and network resources. A datacenter networking architecture is proposed in this paper, which is implemented based on software defined optical networks (SDON) with flexible reconfigurable optical add-drop multiplexer (ROADM). A testbed is built with coordinated virtualization of distributed datacenters and operators multi-domain SDON with flexible ROADM. The overall feasibility and efficiency of two virtual network composition schemes are proposed and investigated on our testbed.

Shared risk link groups-aware virtual link mapping in packet optical transport networks with multi-mode fibers

Mode-spectrum matrix is introduced to describe the multi-dimensional resources in packet optical transport networks (POTN) with multi-mode fibers (MMF), based on which a novel shared backup path protection algorithm is proposed to optimize the allocation of optical resource during virtual link mapping (VLM) in packet optical transport networks.

Dynamic traffic grooming based on auxiliary graph in spatial division multiplexing enabled elastic optical networks

An auxiliary graph (AG) is designed to address traffic grooming under dynamic traffic scenario in spatial division multiplexing enabled elastic optical networks (SDM-EON). Various traffic grooming policies are achieved by adjusting the edge weights of AG, and evaluated through simulation in terms of spectrum efficiency and inter-core crosstalk. Numeric results show that the proposed SDM grooming reduces the effect of crosstalk by decreasing the used cores.

Master Controller Election Mechanism Based on Controller Cluster in Software Defined Optical Networks

In large-scale software defined optical networks (SDON) with tens of thousands of network elements, multiple controllers have to be deployed simultaneously, because single controller cannot bear too many service requests. Then, survivability of controller becomes an important issue for SDON. Controller cluster deployed with master and slave controllers is considered as an effective solution for this issue. A SDON controller cluster architecture is given in the paper, based on which a master controller election mechanism (MCEM) is proposed. Simulation results show that MCEM can get better performance in terms of operation time, traffic loads and fault tolerance compared with Paxos algorithm.

160 Gbaud Nyquist optical time-division multiplexed signal transmission through 4 km emulated free-space turbulence link

An emulation method using Fourier transform and Fresnel theory is utilized to characterize beam propagation through free-space turbulence link. A spatial light modulator is utilized for the generation of phase screens to emulate the turbulence effects based on Fourier transform method. Fresnel theory based scaling is used to emulate the long-range turbulent propagation. Simulation results of 4 km beam propagation are firstly provided based on the method. A single 160 Gbaud Nyquist channel transmission experiment under 4 km emulated free-space turbulence link is then demonstrated. 100 phase screen statuses are generated through the spatial light modulator for 7 turbulence strengths. BER distributions under these statuses are measured to characterize the turbulence influence on the signal. Turbulence induced power fluctuation is found to be main reason of performance deterioration.

First Field Trial of Virtual Network Operator Oriented Network on Demand (NoD) Service Provisioning over Software Defined Multi-Domain Optical Networks with Multi-Vendor OTN Equipment

A novel NoD service provisioning solution is proposed to satisfy the private network need of virtual network operators. The solution is first verified in the real software defined multi-domain optical networks with multi-vendor OTN equipment.