User:AlephGamma/Optical Networks

An optical network is a digital communications medium using lasers or light emitting diodes (LEDs) over optical fiber.

Standards

• Plesiochronous Digital Hierarchy (PDH) - A system for transporting large amounts of telephone and data traffic and to allow for interoperability between equipment from different vendors.
• Synchronous Optical Network (SONET) - An optical standard defined by GR-253-CORE by Telcordia.
• Synchronous Digital Hierarchy (SDH) - An optical standard defined by G.707 and its extension G.708 by International Telecommunication Union (ITU) which is built on experience in the development of SONET.

Both SDH and SONET are widely used today

• SONET in the U.S. and Canada
• SDH in the rest of the world

SDH is growing in popularity and is currently the main concern with SONET now being considered as the variation.

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