Pdh vs sdh describes difference between pdh and sdh

DWDM Basics

DWDM is considered as one of the best technologies to increase bandwidth over an existing fiber plant. It enables one to create multiple “virtual fibers” over one physical fiber. It does this by transmitting different wavelengths (or colors) of light down a bit of fiber. DWDM was initially adopted by long distance carriers because the spending in amplification, dispersion compensation, and regeneration composed most of the network equipment cost in regional and national SONET networks. DWDM became increasingly popular in metro networks when the local exchange carriers grew their networks. Other than fiber exhaustion, traffic volume is the major economic factor for deploying DWDM technology in metro networks.