Optical network component configuration

An optical add drop multiplexer, OADM, comprising:

• a first west port coupled to a first east port by a first filter arrangement, the first filter arrangement comprising a plurality of filter elements associated with respective wavelengths;
• a second west port coupled to a second east port by a second filter arrangement to provide a second optical signal path, the second filter arrangement comprising a plurality of filter elements associated with the respective wavelengths;
• an interconnection arrangement to couple the filter elements of the first and second filter arrangements to respective add ports or respective drop ports, wherein the interconnection arrangement is switchable between:
• a first mode in which the add ports are coupled to respective filter elements of the first filter arrangement and the drop ports are coupled to respective filter elements of the second filter arrangement;
• and
• a second mode in which some of the add ports and some of the drop ports are coupled to respective filter elements of the first filter arrangement or the second filter arrangement.