12.7 FUTURE OUTLOOK
From a transport perspective, DWDM is the main growth tec hnology for metro
networks as required bitrates on a fiber—in particular in the presence of video
services—outpace the ability of single-wavelength transmission technol ogies to
deliver the bandwidth cost-effectively. Moreover, photonic switching technologies
allow for the electrical layer to scale more moderately, as much of the traffic can
bypass electronics in most sites.
At the same time, Ethernet has become much more mature and robust, and is
incorporating vario us mechanisms that will allow it to scale more gracefully—
including fault detection mechanisms, hierar chical addressing schemes (such as
802.1ah and 802.1ad), as well as carrier class switch implementations. ...