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STM-1 (155 megabits per second), |
STM-1 (155 megabits per second), |
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STM-4 (622 Mbps), |
STM-4 (622 Mbps), |
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STM-16 (2.5 gigabits per second), and |
STM-16 (2.5 gigabits per second), and |
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STM-64 (10 Gbps). |
STM-64 (10 Gbps). |
Revision as of 23:02, 7 February 2005
SDH (Synchronous Digital Hierarchy) is a standard technology for synchronous data transmission on optical media.
It is the international equivalent of Synchronous Optical Network. Both technologies provide faster and less expensive network interconnection than traditional PDH (PlesiochronousDigitalHierarchy) equipment.
In digital telephone transmission, "synchronous" means the bits from one call are carried within onetransmission frame.
"Plesiochronous" means "almost (but not) synchronous," or a call that must be extracted from more than one transmission frame.
SDH uses the following SynchronousTransportModules (STM) and rates:
STM-1 (155 megabits per second),
STM-4 (622 Mbps),
STM-16 (2.5 gigabits per second), and
STM-64 (10 Gbps).