Abstract: The present invention is a method to protect a cross-connect OXC/OEXC used to forward at least one signal AB from a main input IN to a main output OUT. Said method comprises the following step: dividing the at least one signal AB into two substantially identical signal parts, a first signal part A and a corresponding signal part B; routing the at least one first signal part A through a first cross-connect OXC1/OEXC1, from the input IN to the output OUT; detection of a failure affecting the at least one first signal part A; interruption of the routing path for the at least one first signal part A; routing the at least one corresponding signal part B through a second cross-connect OXC2/OEXC2, from the input IN to the output (OUT).

Abstract: A method of configuring subnodes, or configuring a system of subnodes, in an optical network ring against both node and fiber failure using an OADM, Optical Add Drop Multiplexer. The network includes a working ring and a stand-by ring and each subnode includes a selective optical filter, an optical 2.times.2 switch and an optical amplifier. The method and the system further include steps of monitoring the inputs and outputs of each subnode at the working and stand-by rings using monitor devices which generate alarm signals upon detection of signal loss at a subnode. As a response to the alarm signal, the state of the subnode, that causes the alarm signal is transferred from a first state into one of a number of possible new states as a function of the generated alarm signal, thereby selecting a switch configuration for the subnode according to the new state to clear the error detected.