Matthias Gunkel

A multilayer cost model for metro/core networks

A capital expenditure model is a key requirement to evaluate multilayer (ML) metro and core network architectures. Based on the Internet protocol/multiprotocol label switching (IP/MPLS), MPLS-transport profile, optical transport network and WDM technology, a detailed capital expenditure model developed by researchers from system vendors and network operators is introduced. Besides current equipment and corresponding prices for the different layers, it also contains predictions for technology evolution and pricing until 2018. We show how to determine the price of anML node by constructing it from components specified in the cost model. We use the model in a case study where we benchmark the price of an integrated IP/MPLS/WDM solution.

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

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.

A dynamic impairment-aware networking solution for transparent mesh optical networks

Core networks of the future will have a translucent and eventually transparent optical structure. Ultra-high-speed end-to-end connectivity with high quality of service and high reliability will be realized through the exploitation of optimized protocols and lightpath routing algorithms. These algorithms will complement a flexible control and management plane integrated in the proposed solution. Physical layer impairments and optical performance are monitored and incorporated in impairment-aware lightpath routing algorithms. These algorithms will be integrated into a novel dynamic network planning tool that will consider dynamic traffic characteristics, a reconfigurable optical layer, and varying physical impairment and component characteristics. The network planning tool along with extended control planes will make it possible to realize the vision of optical transparency. This article presents a novel framework that addresses dynamic cross-layer network planning and optimization while considering the development of a future transport network infrastructure.

Multi-layer capacity planning for IP-optical networks

We consider a pragmatic multi-layer capacity planning approach for an IP over optical network, which builds on existing planning practices. We first describe a router bypass process that considers the real impact of the IP layer topology change, given the actual behavior of the IP layer, leveraging a commercial IP planning tool. We then consider the design and cost impact of several multi-layer restoration schemes. We compute the savings achieved on two real-world core network models. The resulting savings are similar for both networks and are very promising.

Transmission of 200 G PDM-CSRZ-QPSK and PDM-16 QAM With a SE of 4 b/s/Hz

We have realized the first field transmission of 8 × 216.8-Gb/s Nyquist wavelength-division-multiplexing (N-WDM) signals over 1750-km G.652 fiber consisting of 950-km real and 800-km lab fibers with erbium-doped fiber amplifier (EDFA)-only amplification. The average loss per span is 21.6 dB. Each channel is modulated with 54.2-Gbaud (216.8-Gb/s) polarization-division-multiplexing carrier-suppressed return-to-zero quadrature-phase-shift-keying (PDM-CSRZ-QPSK) data on a 50-GHz grid giving a record spectral efficiency (SE) of 4 b/s/Hz. Digital post filtering and 1-bit maximum likelihood sequence estimation (MLSE) are introduced into the offline digital signal processing (DSP) at the receiver to suppress noise, linear crosstalk and filtering effects. We have also investigated the co-transmission of 200 G PDM-CSRZ-QPSK and 200 G PDM 16-ary quadrature-amplitude-modulation (PDM-16 QAM) signals on a 50-GHz grid, and found that PDM-CSRZ-QPSK signals have better bit-error-rate (BER) performance for both back-to-back and 700-km transmission cases. Meanwhile, PDM-16 QAM signals are subject to larger crosstalk from the neighboring Nyquist QPSK channels.

Experimental demonstration of centralized and distributed impairment-aware control plane schemes for dynamic transparent optical networks

We demonstrate and compare distributed and centralized impairment-aware control plane schemes for transparent optical networks with dynamic traffic. Experimental results show that distributed scheme yields one fifth of setup time required by previously reported alternatives.

Network service orchestration standardization

Network services underpin operator revenues, and value-added services provide income beyond core (voice and data) infrastructure capability. Today, operators face multiple challenges: a need to innovate and offer a wider choice of value-added services, whilst increasing network scale, bandwidth and flexibility. They must also reduce operational costs, and deploy services far faster - in minutes rather than days or weeks.In the recent years, the network community, motivated by the aforementioned challenges, has developed production network architectures and seeded technologies, like Software Defined Networking, Application-based Network Operations and Network Function Virtualization. These technologies enhance the highly desired properties for elasticity, agility and cost-effectiveness in the operator environment. A key requirement to fully exploit the benefits of these new architectures and technologies is a fundamental shift in management and control of resources, and the ability to orchestrate the network infrastructure: coordinate the instantiation of high-level network services across different technological domains and automate service deployment and re-optimization.This paper surveys existing standardization efforts for the orchestration - automation, coordination, and management - of complex set of network and function resources (both physical and virtual), and highlights the various enabling technologies, strengths and weaknesses, adoption challenges for operators, and areas where further research is required. A survey of the standardization efforts for network service orchestration.Develeop an orchestration architecture and a taxonomy of technologies.A systematic review of standardization across SDOs.Future direction for automated and converged orchestration standards.This is the first survey to blend service orchestration for SDN and NFV.

Vendor-interoperable elastic optical interfaces: Standards, experiments, and challenges [Invited]

This paper aims to review the status of standardization activities on the black link (BL) and corresponding alien wavelength concepts. It discusses experimental work on filterless optical networks conducted within a dedicated Deutsche Telekom project. The general prospects and existing challenges concerning elastic extensions of the BL are also assessed. Furthermore, we present relevant work on control and management plane interoperability comprising generalized multi-protocol label switching and transport software defined networking aspects. In the second part of the article, we report on the latest dual-vendor experiments on data plane interoperability in terms of digital signal processing technology for next generation 1.28 Tb/s PM-16QAM super-channels. Finally, we present a network reachability analysis based on the widely used Gaussian noise model in the context of data plane interoperability. This analysis estimates the network-wide impact of the single-vendor versus the dual-vendor approach.

On the filter narrowing issues in elastic optical networks

This paper describes the problematic filter narrowing effect in the context of next-generation elastic optical networks. First, three possible scenarios are introduced: the transition from an actual fixed-grid to a flexi-grid network, the generic full flexi-grid network, and a proposal for a filterless optical network. Next, we investigate different transmission techniques and evaluate the penalty introduced by the filtering effect when considering Nyquist wavelength division multiplexing, single side-band direct-detection orthogonal frequency division multiplexing, and symbol-rate variable dual polarization quadrature amplitude modulation. Also, different approaches to compensate for the filter narrowing effect are discussed. Results show that the specific needs per each scenario can be fulfilled by the aforementioned technologies and techniques or a combination of them, when balancing performance, network reach, and cost.

RECODIS: Resilient Communication Services Protecting End-user Applications from Disaster-based Failures

Disaster-based failures can seriously disrupt any communication network, making its services unavailable. Such disruptions may be caused by natural disasters, technology-related failures, or malicious attacks, and they are observably increasing in number, intensity and scale. When network services that are a part of critical infrastructure become unavailable, commercial and/or societal problems are inevitable. The issue of limiting the impact of disaster-based failures needs to be urgently addressed due to the lack of suitable mechanisms deployed in the current networks. The COST CA15127 (RECODIS) Action will fill this gap by developing appropriate solutions to provide cost-efficient resilient communications in the presence of disaster-based disruptions considering both existing and emerging communication network architectures. It will be driven by researchers from academia and industry in strong cooperation with governmental bodies. In this paper, we highlight the objectives of RECODIS, its structure, as well as planned outcomes.