01-10-2012, 04:13 PM
SONET-SDH
[attachment=34946]
Today telephone network is largely based on the evolution of the
first digital infrastructure, based on a TDM system, with strict
synchronization requirements, or PDH − Plesiochronous Digital
Hierarchy:
• SONET − Synchronous Optical NETwork (optical signal, based
rate of 51.84Mbit/s)
• SDH − Synchronous Digital Hierarchy (European standard
equivalent to SONET)
• STS − Synchronous Transport Signal (equivalent standard for
electric signals)
PDH
Digital transmission system (T-carrier, E-carrier)
exploiting TDM to multiplex lower speed
streams into higher speed channel
Every apparatus has its own clock. No networkwide
synchronization is possible
Every clock is different, and therefore
synchronization errors show up
PDH - Synchronization
Positive Stuffing:
[attachment=34946]
Today telephone network is largely based on the evolution of the
first digital infrastructure, based on a TDM system, with strict
synchronization requirements, or PDH − Plesiochronous Digital
Hierarchy:
• SONET − Synchronous Optical NETwork (optical signal, based
rate of 51.84Mbit/s)
• SDH − Synchronous Digital Hierarchy (European standard
equivalent to SONET)
• STS − Synchronous Transport Signal (equivalent standard for
electric signals)
PDH
Digital transmission system (T-carrier, E-carrier)
exploiting TDM to multiplex lower speed
streams into higher speed channel
Every apparatus has its own clock. No networkwide
synchronization is possible
Every clock is different, and therefore
synchronization errors show up
PDH - Synchronization
Positive Stuffing: