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Buy some dark fiber, will you?

Level 12

There is a technology available through most of the United States capable of providing net bit rates in the range of “terabits per second” and extremely low latency. Though big data enterprises like Google, Microsoft and Facebook are already using this for their data transfers, not many Fortune 500 enterprises have considered this. The technology is known as ‘dark fiber’.

What is dark fiber?

During the best years of the bubble in the late 90’s, telecom and other large utility companies foreseeing an exponential demand for network access laid more fiber optic cables than needed. One reason was, they expected a readily available network capacity will help capture the market. Another is, more than 70% of the costs of laying fiber optic cables goes towards labor and other infrastructure development1. It made sense to lay more fiber than needed to save on future labor expenses than laying new ones as and when needed. But two factors left most of these fiber unused:

  1. The development of Wavelength-division Multiplexing (I refuse to explain that, but you can read it up here) increased the capacity of existing optical fiber cables by a factor of 100!
  2. The bubble burst and the demand for network connectivity died down.

In fiber optic communication, light pulses are what carries information and so when transmitting data, the fiber lights up. Any fiber that is not transmitting data remains unlit and is called ‘dark fiber’. Today, the term dark fiber mostly refers to fiber optic cables that were laid expecting demand but is now not in use or was abandoned. There are thousands of miles of dark fiber2 available throughout the United States being sold or leased out by the companies that built them or purchased them from bankrupt telecoms.

Should you consider dark fiber?

Dark fiber is suitable for enterprises that need low latency, high speed connectivity with zero interference from service providers and has the capex to invest. Here are a few scenarios where dark fiber can help.

Point-to-point connections, such as those to network-neutral data centers, cloud providers, DR and back-up sites would do better with Gigabit or even Terabit transfers speeds. Fiber optic cables are capable of exactly that – a single pair of fiber can transfer Gigabits of data per second.

There are enterprises whose bandwidth speed requirements can change from a few Gbps to an unpredictably high limit. Optical fiber is capable of virtually unlimited data speeds allowing it to meet high and unpredictable bandwidth demands.

Enterprises, especially those involved in stock trading or online gaming and those using newer communication technologies such as HD video conferencing and VoIP need ultra-low latency connections which optical fiber is capable of providing.

Dark fiber also provides net neutrality. If you are purchasing Gold class QoS from your ISP for priority data delivery to your data center or branches, dark fiber needs none of that. With dark fiber, data is delivered over your privately owned cable and because of its high bandwidth capabilities, there is no need for traffic prioritization too.

Finally, you get the ability to transfer data from your offices to data centers or the cloud without having to worry about the data being read, modified or stolen. Dark fiber is your private connection where only you have access to both the data as well as the fiber that transmits the data.

And a few more facts:

Dark fiber is an excellent choice if you already have a router that supports fiber connections, thereby ensuring last mile high speed data delivery. But before you consider buying or leasing dark fiber, make sure you have a real business requirement. Here are a few more facts to consider:

  • Renting or buying dark fiber is cheap but you still need to invest in hardware and other equipment needed to light up the cables.
  • Optical fiber is a physical asset that needs maintenance. Consider the costs involved in maintaining the fiber and related infrastructure.
  • The time needed to identify and resolve outages is much higher than with Ethernet. But, on the other side, issues such as cable cuts happen very rarely with fiber optic cables due to the manner in which they are laid.

If dark fiber costs are prohibitive, consider alternatives such as ‘wavelength services’ where instead of the whole fiber, you lease a specific wavelength on the fiber based on requirements.

Still sounds like hype? Trust copper!

Level 15

Good article.


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