Author
Greg Rundle
This blog was first published in Datacenter Dynamics on Sepember 5, 2019.
At the heart of any technology purchase is the question: Will it do the job? Before considering anything else, including price, you must ensure that the solution being considered will serve the intended function. That may sound obvious! But when the product is perceived as a commodity, functionality is often assumed—even with something as critical as fiber.
The importance of fiber characterization
Whenever you purchase or lease a new fiber path, there’s a lot at stake. If the fiber does not meet the requirements for the intended use, it’ll cost you a lot more than the purchase price. It can lead to lost revenue, troubleshooting and maintenance cost and diminished customer satisfaction. So, how can hyper-scalers, MTDCs, large enterprise IT departments and service providers be sure their fiber will perform as advertised? Fiber characterization
Fiber characterization is the process of validating that a fiber path will support a given use before lighting it up. It’s a critical step, not only when expanding or upgrading the network but during the initial build-out as well. In fact, fiber characterization may be one of the most important steps to ensure a solid foundation for your network.
For years, CommScope has been deploying new fiber and helping some of the world’s largest network operators ensure its performance. The following is a helpful step-by-step process for fiber characterization—a collection of best practices cultivated through experience. It’s a great way to ensure that the fiber you need is the fiber you have.
Four steps to a smoother turn up
WYSIWYG
First, you’ll want to validate that the fiber that’s been purchased or leased is what’s been delivered. Unfortunately, fiber providers don’t always provide what the contract promises. As the customer, it is your responsibility to ensure the delivered product (fiber and connector types) not only matches the invoice but is in good physical condition. Fiber that is dirty, bent, poorly connected or has obvious physical defects will not meet the optical specifications detailed in the contract and will have a detrimental effect on the optical network, if not immediately then further down the road when critical network outages will occur.
Validate
Next, validate that the fiber has been properly prepared and installed. Today’s high-bandwidth networks are highly susceptible to any type of signal degradation. The time to minimize fiber issues is before you turn it up by making sure the end-faces are clean and properly cut and spliced. CommScope, for example, uses industry standard analysis to verify all fiber termination faces.
Test (and remediate)
Next, test the fiber to ensure it meets critical performance attributes. These tests include optical time-domain reflection (OTDR), chromatic dispersion (CD), polarization mode dispersion (PMD), insertion loss and optical return loss. Most importantly, if you contract with a third party for testing, make sure to get a full copy of all results.
Be prepared to require remediation from your dark fiber provider. The whole point of fiber characterization is to ensure a smooth and seamless turn up, so testing alone is not enough. You need to be able to fix any problems you find so they don’t cause critical problems later on.
Document, document, document
Finally, document everything, including creating route and span drawings, to make sure you know what you’ve got and can find every connection point when necessary. Other documents that will be helpful include:
- POP Locations
- Cable sizes, duct sizes and key splice Locations
- Circuit identification Utilization by service or customer
- Total loss, including construction paths, connection points and GPS mapping
- Creation of dynamic traces and light paths end-to-end
Larger deployments may require third party project management who will coordinate with your circuit acquisition teams as well as the technical personnel from your fiber vendor. In many cases, additional third parties may be needed to handle fusion splicing or other remedial work. These activities are usually managed within tight timeframes inside of maintenance windows which are scheduled as part of project planning.
For a more concise overview of the why and how of fiber characterization, check out this brief video featuring CommScope’s Rich Soucie, VP Hyperscale and Data Center Services.
