Clara Meusburger

Cost modeling and evaluation of capital expenditures in optical multilayer networks

Optical multilayer networks offer a high degree of freedom in network design, adapting to actual network requirements (demand types, topologies, etc.) and achieving cost-efficient realizations. Capital expenditures are one of the key differentiators for the evaluation of multilayer networks. A realistic cost model for Internet protocol/multiprotocol label switching (IP/MPLS), carrier-grade Ethernet, synchronous digital hierarchy/optical transport network (SDH/OTN), and WDM equipment from which overall capital expenditures can consistently be derived is contributed and discussed. A comprehensive collection of detailed cost values for different equipment types is presented. Furthermore, the cost model is applied to two case studies, one IP/MPLS-over-WDM study and one WDM study with two topologies, showing substitution effects of network elements to achieve overall capital expenditure minimization.

Multiperiod Planning for Optical Networks - Approaches Based on Cost Optimization and Limited Budget

Multiperiod network planning is, especially for cost intensive and long term operated core networks, a necessity to provide cost efficient long term solutions. In this paper we give an overview on commonly used multiperiod planning approaches and compare their cost allocations and dependencies on cost decreasing factors. Furthermore, we propose a new multiperiod approach, which aims at a complete new orientation: Instead of minimizing network costs, a restricted budget is used not only to satisfy occurring demand but also to purchase equipment for future demand requests. With this approach we obtain long term solutions for optical networks with a restricted budget. This Budget-Restricted approach has a strong relation to applications in industry and public authorities. We use for our studies an integer linear optimization model which takes cost optimal routing and also the wavelength assignment into account. Additionally we provide a detailed cost function with a special interest on node costs.

Optimizing the migration of channels with higher Bit-rates

10G can be groomed into 40G channels or transmitted natively, reducing reach of concurrently mixed 40G channels. For long-term migration under traffic growth, optimal network cost is achieved by early investments in 40G-only transmission systems.

Combining multi-period and multi-layer network planning: Ignored potential?

Multi-layer and multi-period network planning can lead to significant cost reductions. Using linear programming we study the effect of their joint consideration for IP-over-WDM networks. Case studies show cost savings surpassing 20% by including forecast knowledge in multi-layer optimization.

Rerouting of 1+1 optical channels: Cost benefits for incrementally planned networks

Re-optimizing 1+1 protected networks for multiple time periods can lead to cost benefits. We show these cost reductions for a topology and a demand scenario applying traffic affecting and unaffecting rerouting of optical channels.

Method to Ensure a Feasible Wavelength Assignment within the Routing-Only Problem for Transparent WDM Networks

In transparent WDM networks, the optimization problem contains the routing and the wavelength assignment problem, which leads to a high computational complexity. We suggest a set of constraints which either ensures a wavelength assignment solution for a calculated routing, or tests a preprocessed routing for a feasible wavelength assignment. First case studies show a remarkable speed up in calculation time as well as an evaluation of the optimality of the planning solution.

Method to Estimate the Break-Even Point Between SLA Penalty Expenses and Protection Costs

Operators invest in network protection to ensure high availability levels for service level agreements (SLAs), which also involve non-fulfillment penalties. Risking penalties, postponing protection is an option to delay investments with an estimatable break-even point.

Scalability of ROADMs for multiple parallel fibers

Growing traffic loads in communication networks demand for cost-efficient multi-degree switching architectures. Implementing reconfigurable optical add/drop multiplexers (ROADMs) offers cost-efficient and highly flexible solutions in terms of wavelength and direction reconfigurability. First, we give an overview of existing ROADM architectures by introducing a classification matrix. In the second part of the paper, we propose and analyze a concept, which can overcome scalability limitations and decrease the cost of ROADMs connected by parallel fiber pairs. This concept is based on the elimination of switching components, while preserving the most important flexibility advantages of a ROADM.