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What is SDH?
In a simple way, it is an information transmission system on optical fiber that can contain various data (Internet, intranet, mpls, video, telephone line, etc.).
But it is explained in a specialized way below.
The term SDH stands for Synchronous Digital Hierarchy and refers to the multiplex technology used in telecommunications. SDH allows low bit rate data streams to be combined into high speed data streams. Because the entire network is synchronous, individual bitstreams can be easily embedded in and extracted from high-speed data streams.
In this case, we can hope that all the difficulty in providing solutions and difficult typing conditions will end.
The initial system was built in 1985 in the United States of America with the term SONET. As a new digital optical transmission system, SONET provided major advantages over Plesiochrone Digital Hierarchy (PDH), while still being able to transmit PDH. ITU-T standard SDH based on SONET. SONET and SDH are compatible with each other. SDH is suitable as a transmission system for broadband ISDN and transmission of ATM cells, PDH signals, Ethernet aggregation, SAN signals and other communication signals.
The basic concept of simultaneous digital hierarchy
SDH technology combines a signal with a bit rate of b and forms a data stream with a bit rate of n x b in a simultaneous network. Unlike PDH, transmission paths have minimal time difference. The concurrent mode of operation allows multiple multipurpose systems, such as communication links for telephone systems, to be inserted at higher hierarchical levels and then removed again by adding and dropping. According to the level defined by the standard, SDH recognizes different hierarchies such as STM-1, STM-4, STM-16 or STM-64 (155 MB, 622 MB, 2,488 MB, 9953 MB) and more. And for more data than stm64, the dwdm system is used. About five percent of the gross data rate is reserved for OAM (operations, management and maintenance) tasks. The data is transmitted transparently through the SDH network in the channel.
