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Dark Fiber - The Backbone Of A Fiber Optic Network

by:TBT     2020-07-24
Dark fiber systems are the unlit, or unused portions of optical cabling systems; it can also refer to the portions of the cabling system not utilized by the owner of the system, but that which is leased out or sold off instead. Originally it referred to the total capacity of the system. A well planned and engineered system providing excess cabling can be a major cost saving factor in planning for future growth.
A well engineered network may contain a massive amount of unused optical cabling. The reason for this is that the main cost factor in installing a cable backbone is the ancillary costs such as labor, permits, duct work and channeling as well as gaining the contracts to cross through others properties. The actual cost of the cable itself represents a fraction of the overall costs.
When designing the cable backbone the engineers often allow for a significant amount of additional cabling to be installed during the initial installation phase. This is practical business decision as it reduces future costs and eliminates the need to add additional cable at a later date as the need arise. Instead the cable is already in placed and must simply be connected and also gives the cable operator the benefit of redundant or backup systems already in place should an existing cable become inoperable.
The major telecommunication companies became the leader of the optical cable markets. With their built in networks, they were able to avoid a lot of the start up costs by working the cable into their existing systems. Their visions of cornering the market on optical cable backbone systems caused them to overbuild the systems. This lead ultimately to driving the price to access the lines downward. The lack of foresight caused many of the providers to ultimately seek bankruptcy protection.
Out of fear of competition many incumbent local carriers stood fast in refusing to make their systems available to outsiders. They feared in doing so they would lose the opportunity to provide many of the lucrative ancillary services which they had envisioned. Their resistance lead to regulators stepping in to require them to lease space. However, their strong lobby was able to preserve certain portions to be exempted from the regulations; such as fiber to the premises (FTTP) installations.
The regulations however were not as broad ranging as many had hoped. With competitive local carriers being exempted from the regulations many still refuse to participate in leasing programs for their backbones. However, to build alliances with other carriers they forced to swap available optical cable space with other carriers.
Some optical cable networks are deferred to as managed networks. These systems are maintained by the carriers by frequent testing utilizing a pilot signal. The signal is sent through the line to check for signal degradation or cable damage. Signal degradation is often caused by bleed over from adjacent lines.
Another type of network is known as a virtual system. In this type of system multiple signals can be sent over the same black fiber optic line by assigning different bandwidths to each data packet passing through the cable. These networks are known for providing a cleaner signal than other systems.
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