sdh

2 definitions found

sdh - Free On-line Dictionary of Computing (26 May 2007) :

  Synchronous Digital Hierarchy
  SDH
  
     <communications, standard> (SDH) An international digital
     telecommunications network hierarchy which standardises
     transmission around the bit rate of 51.84 megabits per second,
     which is also called STS-1.  Multiples of this bit rate
     comprise higher bit rate streams.  Thus STS-3 is 3 times
     STS-1, STS-12 is 12 times STS-1, and so on.  STS-3 is the
     lowest bit rate expected to carry ATM traffic, and is also
     referred to as STM-1 (Synchronous Transport Module-Level 1).
  
     The SDH specifies how payload data is framed and transported
     synchronously across optical fibre transmission links without
     requiring all the links and nodes to have the same
     synchronized clock for data transmission and recovery
     (i.e. both the clock frequency and phase are allowed to have
     variations, or be plesiochronous).
  
     SDH offers several advantages over the current multiplexing
     technology, which is known as Plesiochronous Digital Hierarchy
     .  Where PDH lacks built-in facilities for automatic
     management and routing, and locks users into proprietary
     methods, SDH can improve network reliability and performance,
     offers much greater flexibility and lower operating and
     maintenance costs, and provides for a faster provision of new
     services.
  
     Under SDH, incoming traffic is synchronized and enhanced with
     network management bits before being multiplexed into the
     STM-1 fixed rate frame.
  
     The fundamental clock frequency around which the SDH or
     SONET framing is done is 8 KHz or 125 microseconds.
  
     SONET (Synchronous Optical Network) is the American version
     of SDH.
  
     (1995-03-02)
  

sdh - V.E.R.A. -- Virtual Entity of Relevant Acronyms (June 2006) :

  SDH
         Synchronous Digital Hierarchy (FDDI, ATM, SDH)