1:43 PM 11/16/2006

Two basic cable designs are:

Loose-tube cable, used in the majority of outside-plant installations in North America, and tight-buffered cable, primarily used inside buildings. 

Loose-tube cables are used outside buildings, because they are more likely to be subjected to thermal and mechanical stresses. The loose-tube design allows the fiber to adjust itself mechanically within the cabling.

Single-fiber tight-buffered cables are used to interface among equipment and loose-tube cables.

Multi-fiber tight-buffered cables are used primarily for alternative routing and handling flexibility and ease within buildings.

Multi-fiber cables of various loose-tube designs carry large amounts of data between metropolitan areas and over long distances in harsh environments - such as the ocean floor.

Strengthening materials such as Kevlar are included in both loose-tube and tight-buffer designs.