Issue link: https://www.e-digitaleditions.com/i/1414667
24 I ICT TODAY FIGURE 3: Cloud-based fiber monitoring system. The protective fiber is redundant fiber to be used if the primary breaks. BASICS OF OPTICAL FIBER MONITORING Fiber monitoring and testing, in its simplest form, involves using an OTDR to send pulses of light down a fiber and analyzing the light reflected back toward the OTDR to measure the optical loss over the length of the fiber, as well as the impact and location of specific optical impairments, which may be localized to a specific splice or patch panel. In doing this, the fiber can be tested to ensure it will meet the link budget require- ments of a specific optical transmitter and receiver pair. Additionally, the fiber can be retested periodically to ensure it still meets the optical loss requirements. Modern fiber monitoring systems still use this same technology but have enhanced the overall system to adapt it to ongoing or continuous monitoring. These enhance- ments may involve an optical switch to allow a single OTDR to test more than one fiber—sometimes providing access to as many as 1,024 fibers in a round-robin fashion. They may also involve an optical coupler and a specific OTDR test wavelength to allow monitoring of lit fibers without impacting the customers' services. These systems may take advantage of the cloud-based nature of data centers, deploying advanced management, test orchestration, results gathering, and analytics soft- ware with rich application programming interfaces (APIs) to allow easy integration into the DCI provider's network operations center (NOC) or security operations center (SOC). See Figure 3. Today's fiber monitoring systems can greatly simplify the task of testing and monitoring both lit and dark fiber assets for data center interconnect, core network transport, front-mid-and-backhaul RAN network interconnect, and fiber access networks. However, having visibility into the optical layer is only part of the monitoring story.