a relatively small number of wavelength interchangers the cross connect of the present invention comprises two fabrics and one or more wavelength interchangers that interconnect the fabrics the fabrics are either pathwise strictly non blocking or pathwise wide sense non blocking in the former case the wdm cross connect is strictly non blocking i e both pathwise and wavelength strictly non blocking in the latter case the cross connect is wavelength strictly non blocking and is pathwise wide sense non blocking i e a routing algorithm is required to ensure that any sequence of connection requests and withdrawals can be routed without disturbing any currently routed requests in accordance with the preferred embodiment of the present invention the cross connect is strictly non blocking and comprises a minimum number of wavelength interchangers namely 2k u2212 1 where k is a positive integer equal to the number of input fibers and to the number of output fibers of the cross connect the cross connect is capable of providing a route for any sequence of connection requests and withdrawals without having to disturb any currently routed requests and without the need for a routing algorithm application_number US 47164199 A description prior to describing the wdm cross connect of the present invention the variables that are typically used to describe the properties of a wdm cross connect will be defined a detailed discussion of the wdm cross connect of the present invention will then be provided which will include a proof that utilizes these variables and that demonstrates the strictly non blocking nature of the wdm cross connect of the present invention a k u00d7 k wdm cross connect that supports n gt 1 wavelengths may be defined as a directed acyclic graph c v a u03bb where v.