The CWDM OADM and Mux/Demux plug-in modules are installed in the CWDM system shelf. You connect the CWDM OADM and Mux/Demux plug-in modules to CWDM GBICs that are installed in your switching modules.The CWDM Mux/Demux plug-in modules multiplex and demultiplex four or eight CWDM channels (wavelengths) from a single-mode fiber-optic cable. The four-channel CWDM Mux/Demux module passes straight through four of the eight wavelengths. You can create point-to-point, hub-and-spoke, and ring networks using the CWDM Mux/Demux plug-in modules. Connect your CWDM Mux/Demux plug-in module to CWDM GBICs of equivalent wavelengths that are installed in your switches.