How the internet sends information, data and messages simultaneously to billions of people across the globe is mind boggling to most. And few understand how it actually works—what is underground, over ground, in the seabed; what PoPs are, IXPs, dark fibre, etc.

In a series of blogs that will hopefully shed some light on the various infrastructure components that make our internet ‘work’, we start with Dark Fibre—an element that actually doesn’t do much for us until someone makes it, well… lit.

The traditional meaning of Dark Fibre refers to unused network infrastructure that is a mixture of cabling, switches and repeaters. Data is transported over optical fibre networks by passing light through the cables. If there is no data being transported, there is no light – this means that the fibre is ‘dark’. Dark Fibre is essentially optical fibre infrastructure that is not in use, and is sometimes also called unlit fibre.

When fibre optic cables are laid down, many companies will, in order to future-proof their networks from exponential data growth, overestimate the amount of infrastructure and cabling required. This overestimation coupled with technical advances in the way in which data is packaged means that many optical fibre networks have extra capacity that is not being used. As a result, Dark Fibre networks have developed to take advantage of this extra capacity.

The term ‘Dark Fibre’ has evolved to encompass the practice of leasing ‘dark’ fibre optic cables from network providers and operators.  This is what is called ‘managed dark fibre’ by some. In this instance, a client will lease unused strands of ‘dark’ fibre optic cable to create their own privately-operated optical fibre network rather than just leasing bandwidth. The Dark Fibre network is separate from the main network and is controlled by the client rather than the network provider.

DWDM (Dense Wavelength Division Multiplexing) has been key in the development of Dark Fibre. DWDM is where multiple data signals are transmitted simultaneously over the same optical fibre. Though the data signals are transmitted at the same time, they are transmitted at different wavelengths to keep the data signals separate. DWDM is a method of increasing bandwidth and allowing more data to be sent via optical fibre. Simply put, with DWDM a single optical fibre cable is transformed into multiple virtual fibres.

There are many benefits to using ‘dark’ networks. They require less power and have a higher capacity, generally due to the use of DWDM. Dark Fibre often has better signal strength and is more immune to interference than the fibre making up traditional networks.

VoIP providers rely on network connectivity to ensure calls can be made and received. And as VoIP business phone systems become more prevalent, the underlying networks on which they operate must be fit for purpose, and not susceptible to interference from other traffic. A good VoIP provider should know how to do this, and own enough infrastructure to be able to ensure calls are managed, and routed, in a way that will guarantee voice quality. It is not as simple as just sending a voice packet over your local broadband line. Dark fibre can play an important role in this, and will continue to as VoIP providers grow in scope and popularity.

About VTSL

VTSL is a leading VoIP business phone system provider headquartered in London, UK. With over 10 years of experience, VTSL offers state-of-the art IP telephony for businesses looking for the latest in communications technology. With low per user costs and dozens of professional features included for free, VTSL provides everything businesses need to get, and stay, ahead.