Optical Distribution Networks

Optical Distribution Networks (ODN)

ODN has played a key role in the widespread adoption and deployment of passive optical networks, and development efforts at this stage focus on reducing upfront costs rather than adding functionality. Now, the industry is promoting the introduction of more advanced technologies into the ODN to reduce operating costs and improve access network performance.

For more than 50 years, the "last mile" of telecom operators' access networks has consisted of twisted-pair copper cables, one for every household, bundled together in a tree-like and branch-like physical structure. Cable operators use coaxial sheathed metal cables in similar tree and branch structures. Early Internet services were provided through these now obsolete technologies.

From the early 2000s, PON deployments began in earnest to support "triple-play" service bundling, where faster internet speeds, lower latency and greater video bandwidth are key selling points. Unlike earlier access networks, the "last mile" of the PON network utilizes point-to-multipoint optical fibers, one or a pair of optical fibers starting from the optical line terminal (OLT) and terminating at a passive optical splitter somewhere in the external equipment , and then multiple optical fibers exit from the optical splitter and are connected to devices called Optical Network Terminals (ONT) or Optical Network Units (ONU) or near individual residences. The optical fibers and splitters connecting the OLT and its corresponding ONUs are called Optical Distribution Networks, or ODNs.