Issue link: https://www.e-digitaleditions.com/i/1066130
56 I ICT TODAY 400 Gb Layer-1 connectivity would cost $2.40. If the same 100 Gb- CWDM4 infrastructure is changed to serve 400 Gb-DR4 (PSM4) optics by changing from Duplex-LC to MPO based infrastructure, the additional cost would be $1.47, which is about 5% more than staying with the Duplex-LC architecture. When switching from a Duplex-LC to MPO-based infrastructure, the fiber count is increased by 4x, but the lower cost of PSM4 based optics will offset the total cost. In the second case, it is assumed that the initial infrastructure is based on 100 Gb-PSM4 migrating to 400 Gb-DR4 (PSM4). The additional cost incurred (when compared to a reference $1 for 100 Gb-CWDM4 link) is $0.68. When migrating from a PSM4 at 100 Gb to 400 Gb-FR4 (CWDM4) architecture, the additional cost is $1.64. For the specific structured cabling design, as per Table 2 and per the reasonable assumptions laid out in Table 1, the total cost analysis indicates that it is cost-effective to choose the PSM4- based optical fiber architecture and MPO-based structured cabling for a future-proofed infrastructure. CONCLUSION The choice of optical fiber transceiver has a big impact on the total cost of the link. Decisions made solely based on the cost of optics may not result in optimized cost effectiveness. Rather, a total link cost, which considers all the components of the link, will result in cost optimization. If a data center infrastructure is designed and built only for a single speed, then a CWDM4 transceiver with duplex-LC based cabling and connectivity infrastructure is the most cost-effective option at 100 Gb; at 400 Gb, there is almost no cost differential between the CWDM4 and PSM4-based infrastructure. If the same data center infrastructure is designed for 100 Gb today with the intention of migrating in the future to 400 Gb, while maintaining the cable infrastructure as much as possible, a different conclusion arises. When migration is considered, it is observed that choosing a PSM4 architecture with the MPO-based cabling infrastructure provides the best value, despite paying a bit more for parallel fibers initially. The relatively higher cost of CWDM4 at 100 Gb and 400 Gb is disadvantageous when total link cost is considered. These results and conclusions are based on a particular data center structured cabling configuration, so results may differ if different variables are considered or a unique design is deployed. AUTHOR BIOGRAPHIES: Mike Connaughton, RCDD, is the market segment manager at Nexans Data Center Solutions. He is responsible for strategy related to the data center segment. Mike has been involved in fiber optic cable manufacturing and the ICT industry for over 20 years with experience in engineering and marketing. He is a graduate of Wentworth Institute of Technology. Mike can be reached at mike.connaughton@nexans.com. Rakesh Sambaraju is the applications engineer and Nexans TESLA Sr. expert for Nexans Data Center Solutions where he is responsible for the technical road map by staying current with standards activities, as well as customer demands. Rakesh received his MSc from Technical University of Denmark and a PhD from the Universitat Politecnica de Valencia. For the past 10 years, Rakesh has worked on different aspects of fiber optic and data center communications technology. He can be reached at rakesh.sambaraju@nexans.com. REFERENCES: 1. Sambaraju, Rakesh, Cloud Technology and the 400 Gb/s Ethernet Landscape, ICT Today, pgs. 33-40, 2018. 2. http://psm4.org/. 3. CWDM4 MSA, http://www.cwdm4- msa.org/. 4. Ethernet Transceivers Forecast, Light- counting, 2018. Devices based on CWDM4 technology for the 4-lane coarse wavelength division multiplexing architecture have lasers operating at different wavelengths. These modulated optical signals with wavelength diversity are multiplexed into a single optical fiber using a multiplexer.