Optical Transport Network (OTN) technology remains a key enabler in the wavelength-division multiplexing (WDM) transport domain. Its ability to partition optical bandwidth to satisfy the demands of individual applications and services effectively disaggregates usable capacity from the optical channel itself. Without OTN, the two are inextricably linked. If the data rate of the service is lower than the capacity of the wavelength, the wasted bandwidth cannot be recovered. The efficiencies enabled by OTN segmenting this capacity across multiple services create operational, scalability and total cost (CAPEX + OPEX) benefits.
While OTN has been around since 2004, it has primarily been used by global Tier 1 operators in charge of vast national and international networks, where squeezing out every last drop of bandwidth is essential to streamlining operations and keeping expenses under control. To date, Tier 2 and Tier 3 operators have been less enthusiastic about adopting OTN, choosing instead to light additional lambdas for the cost of a couple of transponders, rather than investing in an entirely new technology platform. For smaller operators, this would have required not only investment in new equipment, but also training for multiple technicians and NOC personnel, and an overhaul of their operating procedures that could impact everything from BSS and OSS systems to reassigning personnel assignments and job functions. That was a lot to content with when the benefits of the technology were negligible.
Two factors, however, have emerged over the last few years that have changed OTN’s impact on these smaller providers and, as a result, they’re beginning to turn to OTN and hybrid-packet/OTN solutions.
The first is the arrival of coherent technology that is massively increasing the capacity available on a single wavelength. At speeds of 10G, service providers were effectively limited to carrying six or eight services per wavelength. A couple of services could be multiplexed together on the same link but it wasn’t a big deal if the capacity wasn’t fully utilized. But, with coherent line rates running anywhere from 100G to 600G, a single link can now carry hundreds of services, all at a lower cost per bit. So, wasting bandwidth means leaving real money on the table. In this new model, Tier 2 and Tier 3 operators are realizing that OTN is the best way to fill available capacity.
The second factor is the need for multi-carrier interconnection. Smaller regional carriers don’t have the same footprint as larger Tier 1 and Tier 2 operators, so they need to ride over third-party networks to provide the end-to-end service connectivity required to meet customer demand. Creating a path over these disparate networks needs a common glue to bind them together. OTN’s globally accepted standard has proven to be the most effective method.