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Fiber Optics Glossary of Terms

 Common Terms Used in the Fiber Optics Industry

  • Buffer Tube - A plastic tube containing a bundle of fiber strands within a fiber optics cable. Most of the cables on CPAU's fiber backbone have 144 fiber strands contained in 12 buffer tubes, each with 12 fiber strands. A substantial price discount is available if all 12 fibers in a buffer tube are licensed simultaneously by a customer. (See also Fiber Optic Cable and Fiber Strand). 
  • Commercial Fiber - A fiber strand without any light flowing through it.  With CPAU's commercial fiber, customers may attach their choice of voice, data, and/or video equipment to the ends of their licensed fibers to "light" the fibers and transmit information between locations.
  • Drop Cable - A fiber cable that is used to connect a customer location to the fiber backbone.  CPAU's standard drop cable consists of 12 strands of singlemode fiber.
  • Easement - The right to use another party's property, typically for a specific purpose, such as to locate a fiber optics cable to be used for telecommunications services.
  • Fiber Backbone - CPAU's network of commercial fiber, consisting of 144 or more strands of singlemode fiber along most of the 28 mile route.  (See the Palo Alto Fiber Backbone Route Map for more details).
  • Fiber Optic Cable - A cable containing a bundle of fiber strands.
  • Fiber Optic Pathway - A physical pathway within a fiber strand through which pulses of light may be transmitted.  Two or more fiber strands may be spliced together from end to end to extend such a pathway.
  • Fiber Strand - An individual glass fiber, roughly the thickness of a human hair that is capable of carrying a distinct signal transmitted in the form of pulses of light.  A single strand of fiber is capable of transmitting over a million simultaneous telephone calls, or nearly 80 gigabits of digital information per second (80,000,000,000 pulses of light per second), using commercial available telecommunications equipment.
  • Interconnection Work - The activities CPAU must perform to establish fiber pathway(s) between two or more locations.
  • License - An agreement between CPAU and the customer that defines the rights and obligations of each party in relation to the customer's use of a portion of CPAU's commercial fiber infrastructure.
  • Multimode Fiber - A type of fiber cable suitable for use with telecommunications equipment that is typically less expensive than that used with singlemode fiber; however, maximum transmission distances are much more limited than with singlemode fiber.  While CPAU's fiber backbone does not include any multimode fiber, CPAU will consider requests for customer multimode fiber cable installations.  (See also Singlemode Fiber).
  • On-Net Building - A building into which CPAU has strategically extended the fiber backbone upon mutual agreement between CPAU, the building owner, and the building occupant.  The Digital Equipment Corporation's Palo Alto Internet Exchange (PAIX) is one such on-net building.  (See Service Providers for more information about PAIX).
  • Route-Diverse Ring - A fiber network design in which fiber pathways along two different routes are used to connect two or more locations.  Because different routes are used, a problem along one route, such as a fiber cut, need not interrupt a signal sent from one location to another because it can also be sent via the other available fiber pathway, if the proper network equipment is used.
  • Singlemode Fiber - A type of fiber cable capable of transmitting light over longer distances than multimode fiber.  CPAU's fiber backbone consists exclusively of singlemode fiber.  Equipment that is designed for singlemode fiber must be used by the customer.  (See also Multimode Fiber).
  • Splice Points  Locations on the fiber backbone at which CPAU will splice fiber cables.  Segments of the fiber backbone are interconnected to each other at these locations.  Drop cables are also connected to the fiber backbone by CPAU at these locations.
  • Splice - A physical connection between the ends of two fiber strands.

For more information about the City's competitively-priced Fiber Optics services and how we can help your business, email darkfiber@cityofpaloalto.org or call (650) 329-2241.

Last Updated: Mar 25, 2015
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