| 摘要 |
<p>PURPOSE: To shorten the clock changeover time for the entire system by adding 1 to a numeral of a synchronization message discriminating clock changeover for a faulty block so as to conduct changeover processing thereby stopping switch back on the recovery of the fault. CONSTITUTION: Each node discriminates changeover of a clock signal based on priority P and a numeral of a synchronization message Q denoting a quality class of a clock transferred simultaneously to select a clock with a higher Q but selects a clock with a higher P when the Q is the same. A clock circulated clockwise from a node 10 is selected usually as shown in figure and when a line fault takes place between, e.g. nodes 10, 20, a clock circulated counter clockwise is selected. In this case, a Q=2 at a fault block of the node 10 is changed into 3, then all nodes including the node 20 doe not require switch back on the recovery of the fault.</p> |
