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Dark fibre: A data centre manager’s toolkit

Fri 26 Jul 2019 | Rob Coenen

Rob Coenen breaks down the top considerations data centre managers should make before plunging into the dark

Between Q1 2018 and Q1 2019, mobile data traffic surged by 82 percent. That eye-popping number is just the latest increase in an almost parabolic curve of mobile data use since 2013. At the consumer level, recent years have seen an explosion of video streaming. For businesses, demand for data-hungry cloud computing and edge computing applications keeps increasing. And the launch of 5G will enable IoT to scale up.

In other words, demand for data is only going to increase from here.

For data centre managers, that means finding ways to enable the flow of data at high speeds – often on a limited budget. One technology that may make that performance boost possible is dark fibre.

What is dark fibre?

First, some quick background: laying fibre-optic cables underground (and especially under oceans) is expensive. In fact, the fibres themselves account for less than 10 percent of the overall cost of setting up this infrastructure.

So when companies lay fibre-optic cables, they typically put in far more than they need to hedge against future increases in data demand. In practice, this means that, alongside the “lit” fibres that run data around the world, there are many “unlit,” or “dark” fibres that aren’t being used.

An organisation can buy or lease one of these fibres – or even a single wavelength within a fibre – to meet its data connectivity needs. Doing so offers an alternative to paying a commercial internet service provider (ISP) like Comcast or AT&T.

Dark fibre vs. ISPs

So why would an organisation go to the trouble of leasing a dark fibre when ISPs are already established and ready to sell their services? The short answer is that it might not – dark fibre doesn’t always make sense.

But for organisations interested in achieving extremely low latency, superior redundancy, privacy, security, or high growth, dark fibre can be an excellent option. Here’s how.

Because of the volume of traffic they manage, ISPs tend to shift data around before delivering it to its destination. The result is (relatively) high latency. This isn’t typically a problem for home use or even many types of business use, but in applications that demand extremely low latency – like a stock exchange – dark fibre offers a direct connection and therefore superior performance with extremely low latency.

Many businesses have redundant networks set up as part of their disaster recovery / business continuity (DR / BC) plan. But often, different ISPs share the same physical infrastructure. In the event of a natural disaster or even a construction accident that caused one provider to go down, the “backup” provider might go down as well. Dark fibres offer true redundancy, as they are completely separate from the physical infrastructure used by ISPs.

Another key benefit of dark fibre networks is that they’re extremely private. Organisations required to maintain certain data security standards (including those in the healthcare industry) may be able to save money on external security measures by opting for a dark fibre network.

For organisations whose data use exceeds 1 Gbps, dark fibre costs may start to beat the costs of ISPs. So even if the network has no particular requirements for latency, redundancy, or privacy, at a certain amount of bandwidth use, dark fibre may simply make financial sense.

This is because the cost of dark fibre is fixed, whereas ISPs charge per data usage; as an organisation exceeds 1 Gbps, those costs can add up fast.

“For organisations interested in achieving extremely low latency, superior redundancy, privacy, security, or high growth, dark fibre can be an excellent option”

Still, moving to dark fibre is a major transition. A data centre must have certain infrastructure in place to make that transition work.

How to prepare a data centre for dark fibre

First, it’s important to make sure the financials work. Unless an organisation already has access to dark fibres, it’s likely you’ll have to lay out a lot of money upfront, largely because the typical lease runs for 10 to 20 years.

While costs will be fixed within that time frame – definitely not the case with ISPs – the setup costs can be significant: In addition to the lease itself, an organisation must make sure it has the budget to buy termination equipment for both ends of the network. One way to fit that gear into the budget is to choose third-party optics, which are functionally identical to OEM equipment for a fraction of the price.

This equipment is what enables the long reach and dense wavelength division multiplexing (DWDM), the technology that enables fibre to operate so efficiently. Essentially, DWDM involves running several light wavelengths through a single fibre so that many streams of data can travel through the same physical space simultaneously.

Another important consideration is data centre staff. You’ll need to have people on hand who can not only get the network up and running but also troubleshoot, patch, repair, and maintain it (as you would with any type of network).

Weigh your options before taking the plunge

Dark fibre can be a cost-effective way to run a high-performance data centre. But it’s important to note that it’s not a one-size-fits-all solution. In rural areas that don’t already have fibre-optic cable infrastructure, for example, an organisation might have to lay its own fibres, which would likely be cost prohibitive.

But the global appetite for data is only getting bigger. Organisations interested in finding effective ways to keep up with that demand without exceeding budget constraints should certainly consider how dark fibre might make that possible.

Experts featured:

Rob Coenen

Vice President of Business Development


connectivity dark fibre fibre
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