Protection Interoperability for WDM Optical Networks

The failure of a single optical link or node in a Wavelength Division Multiplexing (WDM) network may cause the simultaneous failure of several optical channels. In some cases, this simultaneity may make it impossible for the higher level (SONET or IP) to restore service. This occurs when the higher level is not aware of the internal details of network design at the WDM level. We call this phenomenon ``failure propagation