FEATURE
OPEN CABLES
From Closed to Open Cable Systems BY VINCENT GATINEAU AND GEOFF BENNETT
T
of 10 Gb/s per wavelength, non-coherent transmission, but here are over 400 submarine communication cables the trend really began to accelerate when coherent trandeployed under the seas and oceans of the world sponders demonstrated a 4X to 10X increase in wavelength today. With a typical cable having an engineering data rates (to 40 Gb/s or 100 Gb/s per wavelength), and a design life of at least 25 years, it’s not surprising that similar factor increase in fiber capacity. a given cable will have the opportunity to use several Only a small number of optical equipment vendors generations of transponder technology over its lifetime. were able to invest in coherent technology, and this period Or will it? Figure 1 shows the building blocks of a sub(around 2012) also saw a dramatic rise in the marine cable system, showing the breakdown importance of the hyperscale internet content of the wet plant (cable, amps, branching units) providers (ICPs) as not only consumers of and the dry plant (high- voltage management, Thanks to a general submarine network capacity but also active wave mux/demux – usually a ROADM today, acceptance of the value participants in cable consortia. ICPs were wet plant monitoring, optical power manageof open cables, new already leading the charge toward disaggrement, and transponders). When submarine cables were first deployed, it was common praccable systems from 2012 gated, open standard solutions within the data tice to have a single prime contractor for the onward were almost all center as well as over their terrestrial networks between data centers. They began to consider entire system, including the transponders, and designed from scratch the submarine network link as an extension contractual language would typically restrict to be open, and with of that open network architecture, and part the cable operator to buying the transponder commercial terms of that vision was for submarine cables to be technology from that prime contractor. For many years this was simply accepted that allowed a flexible “open” – with no obligations (neither technical as “the way we do things” in the submarine choice of transponders. nor commercial) to use a given transponder type. At that stage there was gradual and, in communications world, but that began to some cases, reluctant participation by wet plant change around the year 2009 when terrestrial vendors toward this process, but eventually it transponder vendors showed that their equipbecame more practical for third-party wet plant monitoring ment would work just fine over existing, dispersion-manequipment to operate with most of the legacy wet plant deaged submarine cables (see sidebar), and that they could ployed. Thanks to a general acceptance of the value of open offer those transponders at lower prices and with shorter cables, new cable systems from 2012 onward were almost lead times than the legacy suppliers. That was still the era MAY 2021 | ISSUE 118
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