Moreover, the number of fiber ports increases as wavelengths move down the optical network hierarchy from high- to low-speed links. The result is a very large number of patch cords, often many thousands, required to connect the lower speed ports.

While this well-organized hierarchy provides flexibility in the configuration of connections, it requires the management of an enormous number of patch cords, bundled into large trunks which must be carried over hundreds of meters. Fiber port documentation and identification present major difficulties, since a connection between a client port and outside plant could involve patching through four or more patch panel/ODFs. When an optical link needs to be reconfigured, identifying the correct port can be so difficult, and the penalties for disconnecting the wrong patch cord so severe, that the fiber is generally stranded in place. The tangle of patch cords worsens with time as the network evolves. 

Maintenance activities also require the time-consuming tasks of identifying the problem fiber, disconnecting ports without disturbing adjacent ports, performing the tests, documentation, alignment, and re-connection. The whole process not only introduces the potential for human error, but frequently results in dirty connectors, which necessitates additional manual intervention.