By Saurabh Patil, Cox Communications; Jason Bishop, Cox Communications
Cox Communications has extensive optical fiber infrastructure comprising over 25,632 route miles of National Optical backbone and in Metro Markets. Cox Communications relies on Backbone to connect all their Metro markets, urban centers, and peering centers to keep everything running smoothly and efficiently. It's an essential tool that ensures seamless connectivity and enables them to serve their customers better. Fiber is an integral part of Cox Communication’s assets, and we in Engineering work constantly to optimize and strategically utilize our fibers for the lowest Total Cost of Ownership (TCO) and better customer experience to transmit Terabits of data. As we approach the Shannon limit to exhaust fiber capacity, what other options do we have as a service provider to keep up with ever-increasing bandwidth demands and capacity pressure from innovation and customer consumption? There is another 15-20% scope to improve spectral efficiency before fiber exhaustion, but that is just a stop-gap for 1-2 years for capacity growth. This problem needs not only engineering innovation from optical vendors and Internet Protocol (IP) routers but also from service providers to rethink how we architect our network and use surgical techniques to use appropriate technology in certain parts of the networks where it's needed. In Cox, we use embedded highly expensive coherent transponders extensively in Backbone, metro, and some cases in access networks as a solution for adding capacity, even if it's short distances. The saying "When you only have a hammer, every problem can start to look like a nail" is undeniably true. Having limited tools or resources can lead to a narrow-minded way of thinking. It's crucial to acknowledge that there are multiple approaches to a problem, and sometimes, it's necessary to step out of our comfort zone and explore unfamiliar tools and routines to find the optimal solution. Here, we use high-power transponder solutions for all our problems with heavy reliance on over-engineering. The consequence is paying a very high significant cost and increasing power consumption. With the introduction and maturity of new coherent pluggable optics, we at Cox Communications are learning to use pluggable optics in Backbone, Metro, and Access to leverage lower pricing and new capabilities. Utilizing these new coherent pluggable optics on high-capacity short spans can offer exceptional spectral efficiency at a reasonable cost. This approach is a strategic method to enhance performance while staying within budget. In this paper, we will discuss how we are re-architecting Cox’s Backbone and metros to overcome Shannon limits and use coherent pluggable optics in Cox’s Next generation Open Line System (OLS) that supports both pluggable (400G ZR, ZR+, ZR++) and traditional transponder architectures for maximum network optimization and cost benefits. Also, we share our experience of doing live production field testing of 400G ZR++ coherent pluggable optics on very challenging spans and its operational impacts and results.