The CWDM is a passive MUX/DEMUX unit, which allows to combine up to eight fiber links into one, to simplify and reduce the cost of long distance fiber installations. At the other location, the combined line is split back up again, so that instead of eight long fiber lines, you would only need one. The Coarse Wavelength-Division Multiplexing (CWDM) technology offers a solution which will increase capacity of existing fiber infrastructure by enabling multiple channels/wavelengths over the same fiber cabling and will reduce costs for a new fiber optic deployment.
You can use a single optical fiber cable to create up to eight independent 1.25Gbps SFP (up to 40km) or 10Gbps SFP (up to 10km) links, offering more affordable alternative to installing more fiber or leasing additional fibers. You can even use 1.25Gbps modules and 10Gbps modules at the same time.