SDH currently defines standard rates and formats and optical interfaces. Today,
mid-span meet is possible at the optical transmission level. These and other related
issues continue to evolve through the ITU-T committees.
ITU-T addressed issues
The set of ITU-T Recommendations defines
•
Optical parameters
•
Multiplexing schemes to map existing digital signals (PDH) into SDH payload
signals
•
Overhead channels to support standard operation, administration, maintenance, and
provisioning (OAM&P) functions
•
Criteria for optical line Automatic Protection Switch (APS)
References
For more detailed information on SDH, refer to
•
ITU-T Recommendation G.703, “Physical/electrical characteristics of hierarchical
digital interfaces”, October 1996
•
ITU-T Recommendation G.707, “Network Node Interface For The Synchronous
Digital Hierarchy (SDH)”, March 1996
•
ITU-T Recommendation G.780, “Vocabulary of terms for synchronous digital
hierarchy (SDH) networks and equipment“ , November 1993
•
ITU-T Recommendation G.783, “Characteristics of Synchronous Digital Hierarchy
(SDH) Multiplexing Equipment Functional Blocks “, April 1997
•
ITU-T Recommendation G.784, “Synchronous Digital Hierarchy (SDH)
Management “, January 1994
•
ITU-T Recommendation G.785, “Characteristics of a flexible multiplexer in a
synchronous digital hierarchy environment “, November 1996
•
ITU-T Recommendation G.813, “Timing characteristics of SDH equipment slave
clocks (SEC)“, August 1996
•
ITU-T Recommendation G.823, “The control of jitter and wander within digital
networks which are based on the 2048-kbit/s hierarchy“, March 1993
•
ITU-T Recommendation G.825, “The control of jitter and wander within digital
networks which are based on the synchronous digital hierarchy (SDH)“, March
1993
•
ITU-T Recommendation G.826, “ Error performance Parameters and Objectives for
International, Constant Bit Rate Digital Paths at or Above the Primary Rate”,
February 1999
•
ITU-T Recommendation G.957, “Optical interfaces for equipments and systems
relating to the synchronous digital hierarchy“, July 1995
An SDH overview
Overview
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Issue 4, November 2006
