October 2022 A third generation of Optical Distribution Networks (ODN) is emerging
The residential optical distribution network (ODN) is the final link between a telecom operator’s Internet, cable and telephone services and its customers. Over the past decade, ODNs have played a critical role in the widespread adoption and deployment of passive optical networks, and have often faded from the limelight, with development efforts focused on reducing initial costs rather than increasing functionality. Now, however, there is pressure from industry to introduce advanced technology into the ODN to reduce operational costs and increase the performance of access networks. LightCounting published a research note today that provides an introduction to this topic.
For fifty years or more, the “last mile” of telecom operators’ access networks consisted of twisted-pair copper cables, one per household, bundled into massive cables in a physical tree-and-branch architecture. Cable operators used jacketed metal coaxial cables in similar tree and branch arrangements. Early Internet services were often laboriously delivered over these now-archaic technologies.
From the beginning of the 21stSt By the late 20th century, the use of passive optical networks began in earnest to support “triple play” service packages where faster Internet speeds, lower latency, and more video bandwidth were key selling points. Unlike previous access networks, the “last mile” of PON networks uses point-to-multipoint fiber, with a single fiber or pair of fibers emanating from an Optical Line Terminal (OLT) and terminating at a passive optical splitter located somewhere located outside with multiple fibers exiting the splitter and connected to or near individual dwellings in a device called an Optical Networking Terminal (ONT) or Optical Networking Unit (ONU). The optical fiber and splitter that connects an OLT to its downstream ONUs is called an Optical Distribution Network or ODN.
First generation ODNs (let’s call them ODN1) were spliced together using highly skilled technicians and expensive fusion splicing machines that required a controlled environment, usually a van, to keep out dust and other contaminants. While this practice was expensive and time-consuming, it resulted in low-loss optical links that worked well.
As of around 2018, a second generation of ODN (ODN2) started deployment using various pre-assembled components provided by Corning, CommScope, Huber+Suhner, Huawei, Fiberhome, Furukawa and others. These products are described in ETSI TR 103 775 published in August 2021. The term “QuickODN” is used to describe ODNs built with pre-packaged components. The main benefit of ODN2 is that on-site fiber splicing is not required and installation is faster and cheaper.
In addition to pre-termination, another key innovation in ODN2 is the use of barcodes or QR codes for each fiber and port, which can be easily entered into an intelligent database to create a digitized optical distribution network. This “Digital Quick ODN” leverages the unique identities of passive ODN elements to create intelligent management functions such as automatic storage of fiber location information, automatic identification of fiber connections, fiber calibration information, and visual guidance for on-site operations.
The advent of pre-terminated and digitally labeled fibers, splitters and fiber handling trays, cross-connects and boxes significantly reduced deployment time and costs for operators, but did little to reduce operational costs. Today is a third generation ODN (ODN3) is being developed that aims to reduce the operational costs of ODNs by introducing active, automated monitoring and intelligence.
Using an optical monitoring system of some kind (based on reflections, introduced delay or other) enables an intelligent management system to automatically identify and locate impairments and failures, down to the level of specific fibers and ports in a single network element. This information is then made available to a centralized network operations center and portable devices in the hands of field engineers. The advantages of being able to “see through” the 1xN splitter in the ODN are significant. Fiber breaks can be pinpointed down to the individual fiber, and idle ports and full ports can be individually identified prior to a service call. And service availability/downtime can be monitored at the level of individual ONU/ONT.
As FTTx is now a mature network architecture among top-tier CSPs, attention is finally being paid to reducing operational costs through more accurate and automated monitoring enabled by third-generation ODNs. We expect other vendors to follow Huawei’s lead in developing products similar to the Fiber Iris to complement their own product offerings.
The full research note is now available for download: If you are a LightCounting customer, log into your account to access; If you are not a LightCounting customer, you can create an account and read this research note on the Resources page of the website (https://www.lightcounting.com/resources).