Protection interoperability for WDM optical networks

The failure of a single optical link or node in a wavelength division multi plexing (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 IF) to restore service, This occurs when the higher level is not aware of the internal details of network design at the WDM lev el. We call this phenomenon "failure propagation." We analyze three types o f failure propagation, called "bottleneck," "connectivity," and "multiple g roups." Then we present a solution based on the definition of appropriate r equirements at network design and a WDM channel placement algorithm, protec tion interoperability for WDM (PIW), Our method does not require the higher level to be aware of WDM internals, but still avoids the three types of fa ilure propagation mentioned above, We finally show the result on various ne twork examples.