| 摘要 |
<p>The invention relates to a system for protection link fault supervision between two nodes (1, 11) in a transmission network. The nodes (1, 11) are connected by first (6) and second (8) transmission lines carrying identical data traffic between the nodes (1, 11). Each node (1, 11) includes a first, active or working, line termination board (2) terminating said first transmission line (6), a second, passive or standby, line termination board (3) terminating said second transmission line (8). Each node also includes a node core (4) with a link supervision block (10). The line termination boards (2, 3) are adapted to report faults to the link supervision block (10), whereupon the node core (4) will switch traffic between the line termination boards (2, 3). In a preferred embodiment of the invention both line termination boards (2, 3) are adapted to report fault state changes spontaneously when they are detected to the link supervision block (10), the link supervision block (10) is adapted to store received fault causes and correlate the latest received fault causes from each line termination board (2, 3) with the latest received fault cause from the other line termination board (2, 3), the system further including a persistency timer adapted to be started by the link supervision block (10) in order to supervise the persistence of a correlation result, if the correlation result has not disappeared during a persistency timer period, the link supervision block (10) is adapted to request the node core (4) to switch traffic between the line termination boards (2, 3).</p> |
