Let’s talk about dark fiber

Dark fiber: concept, pros, cons, challenges and monitoring

There is a very interesting alternative in the market in terms of communications services; we refer to the possibility of leasing or buying dark fiber segments.

Since the 90s of the last century, many companies have been making large investments in laying fiber optic cabling, managing to cover large geographic areas.

Many of these fiber segments have never been used and are referenced with the dark adjective, referring to the fact that light impulses were never passed through them.

In this article, we invite you to review what dark fiber is, what the dark fiber market is like, what its advantages and disadvantages are, the challenges that an organization that opts for this option must face and how monitoring can contribute to face them.

What is dark fiber?

As we said, dark fiber are fiber segments that were never used and that we can now lease or acquire.

These fiber segments are there since many Internet service providers, cable TV providers and even government agencies associated with electric power carried out fiber optic cables to support the delivery of their services.

When they performed a laying project they overestimated the amount of cable required. Among the factors that supported and promoted this practice are:

• Marketing plans aimed at preparing the company for a growing demand.
• The economy of scale that favors the acquisition of large quantities of materials and hire the necessary labor for time.
• The processing of permits of municipalities and other government agencies, in which it was more practical to do the process for a large area than for a single street.

So, there were kilometers and kilometers of fiber optic cable but these were never activated. That is, dark fiber.

The dark fiber business

Some companies saw the data transmission capacity of the dark fiber segments, especially if techniques such as Dense Wavelenght Division Multiplexing (DWDM) are applied.

Indeed, DWDM has become a key technical element for the development of the dark fiber business, since it allows several signals to be transmitted simultaneously through the same fiber optic cable.

The signals are transmitted in unique and separated wavelengths; in this way the same physical cable is converted into several virtual cables.

This makes viable and interesting the marketing under the dark fiber lease scheme.

With this scheme a client can lease the capacity to transmit by fiber or the dark fiber optic threads necessary to create their own communications network.

Thus, the alternative of leasing dark fiber represents an alternative to the scheme of paying for bandwidth to a communications provider, regardless of the technology that said provider manages.

According to the National Commission on Markets and Competition, in Spain there are, since 2016, more than 2 million kilometers of dark fiber available, keeping Red Eléctrica as the main owner with more than 60% of the total. You can check the annual reports on this link.

Who are the customers when it comes to dark fiber?

The dark fiber business has been developed targeting those companies and organizations with high levels of Internet demand in terms of speed and security, and that must transmit a large number of files with sensitive data between different locations.

An interesting example is a company that requires connectivity between two data centers; In this case, it is required:

• A good level of bandwidth.
• A high level of data security.
• A very short latency time and a very high level of link stability.

A company in this condition is an ideal candidate for a dark fiber point-to-point segment.

Thus, reports from companies specializing in dark fiber refer to clients that include government institutions, e-commerce companies and commercialization companies with multiple stores for direct sales.

At the moment, no significant sales levels are reported at the level of small businesses or households.

Advantages and disadvantages

There is an interesting point of this scheme and that the leased dark fiber wires are logically separated from the general network of the provider, offering the possibility that the client has complete control of the resulting fiber optic network.

Under this scheme you rent the fiber threads and you keep the control of the communications network, with all the benefits when it comes to security.

The promise of value of the companies suppliers revolves around rules that emphasize this:

• It recovers the control of your data.
• It constructs your own communications network totally prevailed.

Another point in favor of the dark fiber is the scalability; let us say that a company undertakes a project of connectivity of two localities with a scheme point to point based on dark fiber.

And we also say that initially it decides to establish a scheme of 10Gbps on this connection; therefore it makes the appropriate design, acquires the necessary equipment.

After some time the speed requirements change and a connection of 100Gbps is required; then, it starts from a constant physical platform and it will be required only to update the equipment or in any case to change it.

Cost control is also implicit in this scalability scheme. If the company surely had a service of communications based on another technology the change of bandwidth of 10Gbps to 100Gbps it would imply an increase in the monthly costs.

Now, dark fiber has a serious disadvantage in terms of availability since, although there is a lot of dark fiber available, perhaps for the location required by a certain company there will not necessarily be the possibility of leasing dark fiber.

On the other hand, although the stability of dark fiber links can be very high, for a specific segment it can be complicated to create a fault tolerance scheme, since it will require the lease of another fiber segment or the acquisition of another communication scheme.

Finally, having control of the communications network implies costs and challenges at the technical level that the company that leases segments of dark fiber must resolve in some way. Things like;

• Design, acquisition and implementation of the necessary transmission equipment to be able to bring the dark fiber segments to production.
• The regular maintenance of the segments and any repairs that may occur.

These technical challenges are usually solved by contracting the additional services that the companies that commercialize dark fiber usually contribute.

However, the scope of these companies may be limited; in fact, many of them do not include in their proposals the necessary equipment for the integration of the dark fiber segments.

Likewise, their capabilities are limited in terms of the monitoring of the links and the data that passes through them, so it is vital that the client assumes the activities of constant monitoring of the behavior of the resulting network.

Challenges and monitoring

It is interesting to think about the challenges that a company that decides to bet on technology around dark fiber links must face.

The main challenge is to integrate a fiber segment to the base platform in the most efficient way, which we can also assume that it will pass a large amount of sensitive data.

This integration has certain technical and operational implications that could become a headache for the computer scientists in charge.

One way to avoid problems can be to start the integration from a platform on which a high level of governance is exercised, both at the physical level as well as servers and applications. Which leads us to think about the support that a general purpose monitoring tool can provide to this situation.

In the event that the company does not have an implementation of a monitoring solution, the acquisition or lease of a dark fiber segment may represent the ideal time to start an acquisition and implementation project of Pandora FMS.

If the reader is in this situation we invite you to read a very interesting article published in this blog, which may be ideal to introduce the advantages of network monitoring.

In the best case, the company will have a monitoring system for general purposes such as Pandora FMS fully operational and in this situation we recommend to be alert to the following steps:

1. Platform personnel training : If the management and platform support staff of the company does not have the technical knowledge and experience to give regular maintenance to this type of technology, it is necessary to plan a training plan that covers these needs.
2. Define maintenance and support processes: For the new links, it will be necessary to define the internal processes associated with regular maintenance and the escalation procedure of support cases with the specialized providers.
3. Adjust the visibility platform: It is necessary to integrate the new equipment associated with the dark fiber segments into the network monitoring platform. Include in the IT assets list the equipment associated with the dark fiber segments, update the network maps, evaluate if this equipment supports protocols such as NetFlow or SNMP that allow us to monitor their physical parameters and behavior, evaluate if it is necessary to include hardware elements to capture traffic such as fiber TAP, etc.
   In the following link you can find information about the network monitoring scheme applied by Pandora FMS, which could be the starting point to integrate the monitoring of dark fiber links.
4. Set the required alarms: Adapt the alarm scheme to include those that indicate performance problems in dark fiber links.
5. Review the application monitoring scheme: Starting from documenting the applications whose traffic passes through the dark fiber segments. The transactional analysis of these applications should be adapted to take into account the global performance of the fiber segment and the individual performance of every active component.
   In the following link you can find all the information you may need about the Pandora FMSapplication monitoring scheme.

Finally, if the transmission needs of a company such as volume, security and stability are aligned with the advantages of the dark fiber segments and can also support a high initial investment in terms of reducing monthly costs for communications, then Dark fiber should be considered.

Now, without a doubt, the best situation to face the challenges and disadvantages inherent in this technology is based on having a broad, solid and flexible monitoring platform.

We invite you to share your experiences, doubts and expectations regarding dark fiber by leaving a comment below.