Wavelength path signalling for WSS/WBSS combined optical switches in hierarchical optical networks

Hierarchical optical networks will be a viable solution in creating large-scale networks of the future. The networks control optical network resources in granularity of both wavelength and waveband that consists of a fixed number of wavelengths; thereby, they can reduce signalling processing load and efficiently create virtual private networks. Meanwhile, as the network scale increases, multi-stage optical switch architecture is effective in reducing hardware scale and cost. In this paper, we develop a distributed wavelength path control plane for large-degree, hierarchical optical networks that consist of nodes made by multi-stage wavelength selective switches (WSSs) and waveband selective switches (WBSSs). Along with the wavelength path signalling, optical switch control functions configure WBSSs as well as WSSs. Accordingly, we need to develop an optical switch control mechanism so that end-to-end wavelength path signalling can correctly configure both WSSs and WBSSs. As experimental results, we show that wavelength paths are successfully established and released.