Multiwavelength self-healing ring transparent networks

This paper describes the use of optical cross-connect nodes (as used in RACE project MWTN) for implementing multiwavelength unidirectional and bi-directional self-healing ring networks. A comparison of these two ring structures is presented in terms of the number of wavelength required to satisfy a uniform random traffic demand. Two protection strategies based on the electronic self-healing ring principles are applied to the wavelength division multiplexed (WDM) networks. It is shown how the bi-directional WDM rings can be protected against failure by means of spare wavelengths as well as spare fibres. The proposed network protection schemes are accomplished within the optical network with failure restoration transparent to the layers below. The ring networks described are also flexible and adaptable to changes in traffic patterns.