Monday, July 23, 2018
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Innovation to Counter the Need for Internet Speed Limits
Rockley improves data centers through a combination of photonics and CMOS technology.

Until now, data centers have managed to keep pace with vast quantities of generated and stored data. However, they do so at enormous cost, which will continue to grow as bandwidth demands show no signs of leveling in the foreseeable future. In 2015, annual global IP traffic crossed the zettabyte threshold (that is, 1021 bytes). This quantity of data is simply beyond human comprehension. One zettabyte of data transmission would be akin to watching Netflix's entire HD video catalogue every day, for the next 3 million years.

Our generation of massive volumes of IP traffic is taking its toll. Data centers currently consume about 3 percent of the total global electricity supply — 416.2 terawatt hours last year. Current predictions suggest that we will need 1,000 times more bandwidth than we currently have just to keep up with the demand for Internet services over the next 10 years. We cannot deliver that bandwidth economically with the data center technology in place today.

Network Convolution
The problem with mega-scale data center networks is that they are built inefficiently with equipment that was never intended for networks of this size. We can trace the complexity all the way down to the component level where hardware vendors still operate in silos and build network equipment with discrete CMOS switch chips, transceivers and high-speed electronic chassis constructions.

Switching is still mainly performed with electronic CMOS switches, currently limited from 24 to 36 ports each. A data center with 100,000 or more servers all needing connections requires a vast number of chips in multi-layer architectures to operate. All these components add to network cost, management complexity and power consumption, and do not scale along with the rest of the data center.

To a certain extent, this lack of scalability can be alleviated using high-radix chassis switches. However, at a component level, these switches are little more than low-radix switching chips connected internally in a Clos topology using expensive high-speed circuit boards and backplane technologies, and are ultimately governed by the same inefficient rules.

Scaling Efficiencies
Rockley Photonics, a specialist in the creation of scalable data center networks, uses an integrated combination of silicon photonics and traditional CMOS technology to lower the cost of data centers and to power efficient scaling of the network. This is recognized as the path forward in the face of a slowing Moore's Law that has served CMOS electronic advancements for generations.

The packet switching approach consolidates the majority of the functional elements (and value) of the network within a single module. The module contains the packet processing, switching, backplane and transceiver functionalities into a fiber-in/fiber-out unit that can be interconnected to operate like a single switch. The switch's size can range from standard up to unprecedented levels of scaling capable of interconnecting all the racks in a mega-scale data center.

This approach offers several benefits. As optical interconnects are already widely deployed for high-speed transmission between processing elements, the smart integration of the technologies and integrated optical interfaces maximizes the transmission of data in the optical domain. This alone reduces both cost and power consumption as the need for high-speed signals through copper in PCBs and backplanes is virtually eliminated in the network.

The port density is drastically increased, and the modular architecture allows operators to scale the network in tandem with compute resources, without adding additional complexity. The CAPEX and OPEX benefits are inherent with greater port density as this allows the deployment of much larger switches in the same space as competing solutions.

A more efficient, lower latency network enables workloads and bandwidth to be distributed more effectively across the servers leading to more efficient compute functionality and better utilization of the compute resource at hand. As the server compute resource commands the vast majority of the overall DC power requirements, the realized savings can be substantial.

The Known Unknowns
Photonics and fiber optics have become the transport heroes in the central nervous system of the digital ecosystem, with the IT and telecoms industries investing billions in R&D each year. Rockley's solution benefits from Moore's Law scaling in CMOS technology and in the rapid advances in photonics. In time, these combined advances could reduce networking costs and power consumption by a factor of ten.

Network infrastructure on its own generally represents between 12 and 15 percent of data center power consumption, not including HVAC. Using the total global energy consumption of data centers last year, this could represent a savings of 45-56 terawatt hours per annum, equivalent to the full capacity of nearly seven 1 gigawatt nuclear reactors.

In order to meet the demands of tomorrow in an environmentally responsible way, we must adopt a multi-faceted strategy. The software-defined data center (SDCC) is already driving greater efficiencies, while investment in renewable energy is taking an increasing number of data centers off the grid altogether.

Through new thinking and the application of new technologies throughout the data center network, it will be possible to recalibrate the cost trajectory of networking, and in turn, help decouple the inevitable growth of data centers from the resources needed to power them.


Contact: Rockley Photonics, 234 E Colorado Boulevard, Suite 600, Pasadena, CA 91101 626-304-9960 Web:

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