● Introduction ● Why OTN? ● Advantages ● Interfaces ● Properties ○ Architecture and Overhead ○ TCM ○ FEC ● Testing ● The future of OTN
Introduction ● OTN = The Optical Transport Network ○ specified in ITU-T G.709 standard ● ITU-T definition: “a set of Optical Network Elements connected by optical fiber links, able to provide functionality of transport, multiplexing, switching, management, supervision and survivability of optical channels carrying client signals.” ● aim is to enable the multiservice transport of packet based data and legacy traffic (Next generation SONET/SDH)
Why OTN? ● Operators’ need to use existing fiber to satisfy Growing demand for services and bandwidth ● DWDM increased fiber bandwidth, but lacked protection and management capabilities. ● OTN Combines the benefits of SONET/SDH with DWDM
Advantages ● Protocol transparency ○ Integrity of the client signal is maintained. ○ End user views exactly what was transmitted. ● Backward compatibility for existing protocols. ● Better switching scalability ○ OTN is able to switch at a higher bit rates than SDH.
Advantages ● Better Forward Error Correction (FEC) ○ G.709 FEC algorithm result in up to 6.2 dB improvement in Signal to Noise Ratio (SNR). ○ Increased span length ○ Can increase number of channels ○ an enabler for transparent optical networks ● Tandem Connection Monitoring (TCM) ○ Unlike SDH, OTN has six TCM fields. ○ Allowing each network to be monitored.
FEC ● detects 16 bit errors, corrects 8 bit errors.
Benefits of FEC ● Gain in power level. ● Network operator can accept a lower quality signal ● Reduction in the use of 3R regenerators ● Early warning capabilities
Optical multiplex section(OMS) ● consists of multiplexed OChs Optical transmission section (OTS) ● transports the optically multiplexed sections ● perform monitoring and maintenance between optical network elements
Testing ● To guarantee bandwidth availability and quality ● introducing alarms and errors in the system and measuring their effects on the transmission ● E.g. stimulus testing, mapping/demapping testing, FEC error testing.