SDH multiplex structure

 Synchronous Digital Hierarchy (SDH) is a CCITT standard for a hierarchy of optical transmission rates. Synchronous Optical Network (SONET) is an ANSI (American National Standards Institute) standard for North America, that is largely equivalent to SDH.
Both are widely spread technologies for very high speed transmission of voice and data signals across the numerous world-wide fiber-optic networks.
SDH and SONET are [...]