When Should You Consider Dark Fiber?

As enterprise networks grow more sophisticated and expand into needs for high bandwidth optical backbone connectivity, enterprises often consider purchasing dark fiber. If your company is at this point, there are a few important things you should keep in mind.

First, make sure you buy dark fiber for the right reasons. Dark fiber is great for companies that are growing quickly and need to manage scalability for point to point connections. Whenever you want to upgrade bandwidth, you can change out your equipment interfaces yourself without coordinating with a carrier or worrying about term liability on a leased circuit. That’s great for companies whose bandwidth needs can change rapidly or unpredictably.

Dark fiber is also good for companies who need to manage the technology evolution on their high bandwidth data connections. This is sometimes the case for connections between data centers that require a variety of interfaces that may not be standard or available from carriers servicing those locations. Lighting the fiber with your own equipment also allows you to customize your network performance reporting by giving you direct access to the full suite of PM stats offered by your equipment.

For you low-latency wonks, dark fiber will give you the ability to squeeze out an additional few microseconds by selecting your own highly specialized transmission equipment. Or better yet, you may be able to eliminate equipment altogether from connections short enough to cross-connect the dark fiber directly into your routers or other terminating equipment.

But buying dark fiber is not like buying most other telecom services because it’s more like a physical asset than a service. The fiber itself must be maintained and repaired when there are problems like fiber cuts, and these outages are typically much longer than other services, so you should be careful to negotiate acceptable SLAs for these repairs. Longhaul dark fiber, in particular, is complicated because it requires optical regeneration or amplification. This means you have to figure out how to remotely monitor and maintain that equipment, which, depending on the route, could be in far-off and difficult to access locations.

If you need diversity or restoration in your network, you should be especially careful before buying dark fiber. Many carriers use the same right-of-way when they construct their routes, so you’ll need detailed route maps to validate your diversity.

Dark fiber can be the right solution for many of today’s high-bandwidth enterprise connectivity needs, but make sure you go into it with a full understanding of its advantages and disadvantages.

When to buy it:

– When you need to control scalability

– When you need to control network management

– When you need to manage technology evolution

– When you need to manage latency extremely tightly


– Longhaul dark fiber purchases

– Reliability

– Diversity

– Maintenance and repair

– Flexibility

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I am currently senior vice president, global core product management.

3 thoughts on “When Should You Consider Dark Fiber?

  1. Note about dark fibre key point is company will not be “buying dark fibre” they will always be renting / leasing said item.

    Only tecloms generally have access to direct ownership methods for long-haul dark fibre, as above stated maintenance and repair of long-haul fibre is unfeasible for 99.99999% of non telecom companies. Even getting placement of said fibre is rediculously impossible now adays. Have to go through regulations that take most companies out of context of their current business plans to even attempt such a deal. To re-iterate, they will simply rent / lease thier is no ‘buy’ ‘drop own lines options’ for a non telco of dark fibre.

    • Thanks for the comment. You are correct in that Enterprises cannot “buy fiber” in the sense of taking a “legal transfer of asset title”, but very few carriers do this either. Almost all “fiber sales” come in the financial form of a lease or an IRU (Indefeasible Right of Use) under a fixed term. So when I used the term “buy”, I was referring to purchasing an IRU, which is generally paid in full up front with a recurring payment for ongoing O&M (Operations and Maintenance) support.

  2. Pingback: Reshaping the Data Transport Sector: The History of Dark Fiber Networks | Mosaic NetworX

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