International Business Machines Corporation

Chienho Chen

Masakazu Satoh

Kazunari Suzuki

Takashi Murata

In one general embodiment, a method for setting a value of waiting time for switching is provided. At a node in a sonet ring, it is determined which path to the node is an actual path and which path is a preliminary path. Additionally, it is determined whether a one way fiber transmission delay of the actual path is less than a one way fiber transmission delay of the preliminary path. If the one way fiber transmission delay of the actual path is greater than the one way fiber transmission delay of the preliminary path, a switching time is set to zero and normal switching is performed. If the one way fiber transmission delay of the actual path is less than the one way fiber transmission delay of the preliminary path, a switching time is set equal to the one way fiber transmission delay of the preliminary path minus the one way fiber transmission delay of the actual path and it is determined whether a path alarm indication signal (AIS) occurred in the actual path. If the path alarm indication signal occurred in the actual path, path switching of the actual path is stopped within the switching time and it is determined whether a path alarm indication signal occurred in the preliminary path. If the path alarm indication signal did not occur in the preliminary path, normal path switching is performed for the actual path.

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Shinagawa-ku, Japan

Chienho Chen