Discuss the potential applications of optical technologies and identify their fundamental roles in basic transport network functions. It is demonstrated that the instruction of optical layers not only offers quantum leaps in both transmission capacity and routing node throughput simultaneously

but also allows effective accommodation of different signal formats and protocols. Next

the transport capability of large capacity WDM system is shown

and the effect of fiber amplifiers and nonlinearity is discussed. Finally

the technologies needed to realize reliable communication is clarified

and the optical network protection strategy is discussed.