Growing Connections: How Demand is Driving Optical DCI

Fuelled by increasing demand, optical data centre interconnect (DCI) -- which sees multiple data centres connected together -- is a fast-growing market. In 2016, optical DCI grew 63.5% and contributed over $1.69 billion, with total optical infrastructure finishing the year at $13.6 billion, according to analyst ACG Research.

The analyst predicts the worldwide optical infrastructure market will grow from $13.6 billion in 2016 to $17.3 billion by 2021. At the same time, purchases of optical DCI equipment are expected to grow from $1.69 billion in 2016 to $4.3 billion in 2021.

Meanwhile, sales of DCI gear, principally to internet content providers and enterprises, grew 49% in 2016 to reach $1.9 billion, according to IHS Markit’s DCI, optical transport network and packet-optical hardware report.

So, what is driving the need to connect multiple data centres together? When larger data centres are created, the biggest limitation is typically power, says Amie Cox, global ICP sales leader for VIAVI Solutions.

She explains: “You can’t just keep building on a data centre as there won’t be enough power from the grid to support it. So they create a data centre in another power zone to build on this and interconnect them together.”

The resulting network of data centres requires testing to make sure connectivity is there and at the rates expected. VIAVI is one company that carries out these tests on the fibre and dense wavelength division multiplexing (DWDM) systems, explains Cox. “The first thing we do is a fibre inspection – making sure the fibre is clean. You’d be amazed at the issues that dirty fibre creates: a speck of dirt blocks the transmission.”

Fibre is an essential component in DCI: after all, it is technology such as this that allows the transport of critical assets between data centres.

Driving adoption
Because they have the greatest demand for high speed connectivity and bandwidth, large cloud providers such as Amazon, Google and Microsoft are driving the optical DCI market, says Lisa Huff, principal analyst, Discerning Analytics. “The services they provide to end users need bandwidth, reliability and connections,” she says.

This factor, among others, means the predominant market driver for optical DCI is the need to scale, says Ayotunde Coker, managing director of Rack Centre.

Coker speaks from experience. Based in Nigeria, Rack Centre is a carrier neutral data centre – and the largest and most connected in West Africa with undersea cables connected directly to the country.

He explains: “What we are finding is, being carrier neutral we are interconnecting carriers into carriers, and we are interconnecting customers into the internet exchange point in Africa. As volumes increase, the efficiency of interconnection comes into play.”

Content providers and telecoms firms are driving the requirement for ever-greater speeds, says Coker. “Demand will come from these sectors so you have to scale to meet expectations.”

In addition, Coker says, Rack Centre’s home market of Africa is a growth area for connectivity because its median age is very young – between 18 and 22. “There is significant potential there for scale; the growth potential is high,” says Coker.

It is true to say that data centres have specific requirements for interconnections, says Jan Radil, senior researcher, optical networks, CESNET – who adds that the views expressed are his own and do not necessarily represent the views of CESNET.

For example, he says: “There are huge data volumes, low latency is important or even crucial – and latency is dependent on distances.”

Taking this into account, he says: “Fibre infrastructure is just a given. However, chances to move fibre routes are limited, so it is important not to add additional delay.”

Challenges in optical DCI
The market is growing but there are issues that must be resolved as large amounts of information is transferred between data centres. The challenges lie in the management of connections, including cyber security, says Huff.

This will continue to be a concern as amounts of data increase in tandem with a growing number of cyber-attacks. But Radil points out that security on the optical layer is already considered to be “rather robust”, with line cards providing encryption.

As a retail data centre colocation and interconnection services provider, Equinix is facing growth challenges to build and operate optical DCI transport networks, according to Rao Lingampalli director, network architecture at the firm.

He adds: “Challenges to address in DWDM transport include compact foot print, low cost, high capacity, and flexibility of offering multiple rate and protocol services between data centres.”

But at the same time, multiple innovations within optical DCI are helping to overcome these issues. Technology innovations and requirements include flexible-grid line system architectures in compact 1RU and 2RU router footprints; multi-rate – from 10G to 100G; and multi-protocol including Ethernet and fibre channel clients on DCI in 1RU, says Lingampalli.

Indeed, the optical layer can provide new opportunities, says Radil. For example, he says there is a trend seeing the ‘white boxes’ known from the Ethernet and IP worlds coming to the optical domain. He claims that CESNET started this trend more than 10 years ago, with the development of its Czech Light TM – a family of advanced open optical equipment.

Meanwhile, he says: “With optical white boxes and related disaggregation, so-called Alien Wavelengths can offer new possibilities to connect different equipment and administrative domains.”

As data volumes surge, there is much more to come in optical DCI. Radil cites the example of another trend, spectrum as a service. “In other words, part of available optical spectra can be offered to third parties, especially with ‘flexible grid’ equipment,” he explains.

It is clear there are challenges ahead in optical DCI, but the area also offers multiple opportunities as new technology becomes available. As for the future, Huff predicts: “We will see 400G connections next, then software defined networking (SDN) and network functions virtualisation (NFV) put into this equipment.”

The focus now is on increasing and maximising the capacity on any one fibre, says Cox. “It’s expensive to add more fibres. So, improvements within DCI are monetised through cost savings and efficiency gains.”

— Kate O'Flaherty, Technology Journalist