The document evaluates the worst case switching delay for a unidirectional signal fail in a 16 node ring network with a maximum length of 1200 km. It considers the processing delays at switching and pass-through nodes, message validation time, and transmission delay over fiber. The total switching delay is calculated as the sum of the processing delays at nodes A through F, the intermediate node pass-through delays, and the long transmission delay over the fiber path, which is estimated as (15/16)*1200*0.005.