Featured Topic: Ensuring the Health of Tomorrow’s Fiber LANs
The health of your network depends on the quality of your network infrastructure — This quality begins with complete certification by contractors or systems integrators that the cabling infrastructure was properly installed. Maintaining a reliable fiber plant is also essential in protecting your business-critical applications. As a network administrator, it is important to understand how to get the best performance from your cabling investment and how to solve problems quickly when they occur.
Fiber optic cable is the media of choice for demanding high data rate applications like Gigabit to the desk and 10 Gigabit Ethernet within the Data Center. Continual improvements in optical fiber performance, fiber cable designs, opto-electronics, connectivity technology, and test equipment have made fiber LANs less expensive, easier to install, and capable of meeting increasing bandwidth demands.
When working with fiber, it is important to understand industry best practices, standards requirements and what are the right test tools to help maintain and troubleshoot fiber optic networks.
Fiber Network Installation and Certification
Network cabling certification is the process of measuring network cabling performance parameters and comparing the results against industry or user-defined performance standards. Certification recommendations such as TIA’s TSB140 bulletin titled “Additional Guidelines for Field-Testing Length, Loss and Polarity of Optical Fiber Cabling Systems” provides guidelines on how to test fiber optic cabling systems in the field - offering two tiers of fiber network certification.
Basic or Tier 1 fiber certification is required in all fiber optic cabling links. The Tier 1 tests are attenuation (insertion loss), length and polarity. When conducting Tier 1 testing, each fiber link is measured for attenuation and results are documented. This test ensures that the fiber link exhibits less loss than the maximum allowable loss budget for the immediate application
Extended or Tier 2 fiber certification supplements Tier 1 testing with the addition of an Optical Time Domain Reflectometer (OTDR) trace of each fiber link. An OTDR trace is a graphical signature of a fiber's attenuation along its length. You can gain insight into the performance of the link components (cable, connectors and splices) and the quality of the installation by examining non-uniformities in the trace. An OTDR trace does not replace the need for insertion loss measurement, but is used for complementary evaluation of the fiber link. This test certifies that the workmanship and quality of the installation meets the design and warrantee specifications for current and future applications.
An OTDR trace helps characterize individual events that are invisible when conducting only loss/length (tier 1) testing. Only with a Complete fiber certification, installers have the most complete picture of the fiber installation and network owners have proof of a quality installation.
Maintaining Fiber Infrastructure Performance
OTDRs are also used for maintaining fiber plant performance. An OTDR allows you to see more details on cable installation, termination quality and provides advanced diagnostics to isolate a point of failure that may hinder network performance. An OTDR allows discovery of features along the length of a fiber that may affect fiber reliability. OTDRs characterize features such as attenuation uniformity and attenuation rate, segment length, location and insertion loss of connectors and splices, and other events such as sharp bends that may have been incurred during cable installation.