PROTECTED BIDIRECTIONAL WDM NETWORK

摘要

An optical WDM ring network includes at least two add/drop nodes connected i n a ring path. The ring path comprises only a single optical fiber (1) arrange d for bidirectional traffic between the nodes. A 2x2 switch (33) is used in on e (B) of the add/drop nodes for switching signals forwarded from the node to t he other node (B) to travel either on a first segment of the ring path or on a second, complementary segment of the ring path when required for protection purposes. Signals from the other node to the first node are issued to travel on both segments but the switch selects the actual segment from which the signals are received in the first node. The signals switches by the switch c an be high priority signals used in protected channels communicated between the node and another node. On the segment from which the high priority signals a re not received, low priority signals in non-protected channels can be communicated between the nodes, these channels also passing the switch.