Definition

SDH (Synchronous Digital Hierarchy)

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 (Plesiochronous Digital Hierarchy) equipment.

In digital telephone transmission, "synchronous" means the bits from one call are carried within one transmission frame. "Plesiochronous" means "almost (but not) synchronous," or a call that must be extracted from more than one transmission frame.

SDH uses the following Synchronous Transport Modules (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).

This was last updated in April 2007

Dig Deeper on Telecommunication networking

Join the conversation

2 comments

Send me notifications when other members comment.

Please create a username to comment.

I'll like to register the SDH
Cancel
Get AppleTV4K and you be set
Cancel

-ADS BY GOOGLE

File Extensions and File Formats

SearchSDN

SearchEnterpriseWAN

SearchUnifiedCommunications

SearchMobileComputing

SearchDataCenter

SearchITChannel

Close