ABSTRACT
References .........................................................................................................267
Coarse wavelength division multiplexing (CWDM) already started to show up in the metro access network in late 1999 [1] before finally the new ITU-T G.694-2 standard went into effect in 2002 [2]. The metro segment was an interesting new telecommunication market that was growing rapidly and needed a low cost “plug and play” solution. What made the metro especially interesting was that it was rich in a wide variety of communication protocols that all evolved in parallel as customer demand for bandwidth grew. Further, the metro network is a lucrative target for service providers who could provide the bandwidth quickly to medium to large businesses. The long haul network had been built and many users in cities around metropolitan areas wanted an internet access on-ramp. Dense wavelength division multiplexing (DWDM) was the first consideration for providing the needed capacity. DWDM had been a proven technology to build out the long haul section of the network and was therefore the obvious first choice. However, DWDM proved too costly, even at short distances with no amplifiers. Then CWDM
was introduced as a new possibility for low-cost multi-wavelength transmission. Small service providers hailed CWDM as the answer over DWDM. CWDM was regarded as a “poor man’s” way of building a metro ring. Validation of the CWDM market came soon when multitudes of vendors appeared with CWDM pluggable transceivers and passive optical equipment.
