the present invention provides a wide - sense , non - blocking wdm cross - connect that utilizes a relatively small number of wavelength interchangers . the cross - connect of the present invention comprises first , second and third fabrics and one or more wavelength interchangers that interconnect the first and second fabrics . demands that require a change in wavelength are routed through the first fabric , through one or more of the wavelength interchangers , and through the second fabric . demands that do not require a change in wavelength are only routed through the third fabric . a routing algorithm is utilized to ensure that any sequence of connection requests and withdrawals can be routed without disturbing any currently routed requests .