An integrated reconfigurable planar lightwave add-drop (RPLAD) multiplexer
for use in a WDM optical communication system is arranged such that each
drop port can receive any wavelength channel and each add port can
transmit on any wavelength channel. Drop port reconfigurability is
achieved by integrating a cross-connect functionality into the RPLAD,
illustratively using optical 1.times.2 switches to perform "space"
switching. The switches are controlled from a remotely located node
controller. Add port reconfigurability is achieved by having tunable
lasers and a wavelength independent optical power combiner, which may be
a star coupler that is integrated with the other above-mentioned
elements. The RPLAD has a modular architecture, so that when RPLAD's are
connected by dual unidirectional transmission rings for the purpose of
redundancy and failure protection, an RPLAD that fails can be removed and
the remaining module can be reconfigured so as to re-route incoming
traffic backwards around the still operating optical communication ring.