Hitless path switching ring network, hitless path switching transmission system, node device for a hitless path switching ring network, and failure occurrence-time hitless path switching transmission method in a ring network

A hitless path switching ring network comprising at least two node devices connected in ring form through a work transmission line and a protection transmission line, wherein at the time of normal operation a signal is transmitted with said work transmission line;

• at the time of failure occurrence in said work transmission line the signal can be transmitted with said protection transmission line in the same direction as the direction in which the signal was transmitted before failure occurrence in said work transmission line;
• in order to cause the signal to be received from one of said node devices to the other of said node devices without instantaneous hitting of the signal at said time of failure occurrence in said work transmission line,
• said one node device includes a fourth memory section for storing the signal being transmitted onto said work transmission line at said time of normal operation, and a second read control section for reading out the transmitted signal held from said fourth memory section before failure occurrence in said work transmission line and sending out said transmitted signal through said protection transmission line in said same direction, at the time of failure occurrence in said work transmission line;
• and
• said other node device includes a fifth memory section for storing the signal received through said work transmission line at said time of normal operation, a sixth memory section for storing the signal received through said protection transmission line according to said second read control section of said one node device at the time of failure occurrence in said work transmission line, and a second phase adjusting section for matching a time phase of the received signal stored in said fifth memory section after failure occurrence in said work transmission line with a time phase of the received signal stored in said sixth memory section before failure occurrence in said work transmission line and outputting said received signal to the outside.

A hitless path switching transmission system comprising at least two node devices connected in opposition to each other through a work transmission line and a protection transmission line, wherein at the time of normal operation a signal is transmitted with said work transmission line;

• at the time of failure occurrence in said work transmission line the signal is transmitted with said protection transmission line;
• in order to cause the signal to be received from one of said node devices to the other of said node devices without instantaneous hitting of the signal,
• said one node device includes a thirteenth memory section for storing the signal being transmitted onto said work transmission line at said time of normal operation, and a fifth read control section for reading out the transmitted signal held from said thirteenth memory section before failure occurrence in said work-transmission line and sending out said transmitted signal through said protection transmission line at the time of failure occurrence in said work transmission line;
• and
• said other node device includes a fourteenth memory section for storing the signal received through said work transmission line at said time of normal operation, a fifteenth memory section for storing the signal received through said protection transmission line according to said fifth read control section of said one node device at the time of failure occurrence in said work transmission line, and a fifth phase adjusting section for matching a time phase of the received signal stored in said fourteenth memory section after failure occurrence in said work transmission line with a time phase of the received signal stored in said fifteenth memory section before failure occurrence in said work transmission line and outputting said received signal to the outside.

In a hitless path switching ring network node device connected in ring form with one or more node devices through a work transmission line and a protection transmission line wherein at the time of normal operation a signal is transmitted with said work transmission line and at the time of a failure occurrence in said work transmission line the signal can be transmitted with said protection transmission line in the opposite direction from the direction in which the signal was transmitted before failure occurrence,

• in order to cause the signal to be received at another node device without instantaneous hitting of the signal at said time of failure occurrence in said work transmission line, the node device comprising:
• a first memory section for storing a transmitted multi-frame signal, having
• an identifier representing a leading position of the multi-frame signal and which identifier is to be used for matching a time phase between received multi-frame signals from different directions before and after failure occurrence at a reception side, during at said time of normal operation;
• and
• a first read control section for reading out said transmitted multi-frame signal with said identifier, stored before failure occurrence, from said first memory section and sending out said transmitted multi-frame signal with said identifier through said protection transmission line in the opposite direction, from the transmission direction employed before failure occurrence in said work transmission line, at the time of failure occurrence in said work transmission line.

In a hitless path switching ring network node device connected in ring form with one or more node devices through a work transmission line and a protection transmission line wherein at the time of normal operation a signal is transmitted with said work transmission line and at the time of failure occurrence in said work transmission line the signal can be transmitted with said protection transmission line in the opposite direction from the direction in which the signal was transmitted before failure occurrence,

• in order to cause the signal to be received at another node device without instantaneous hitting of the signal at said time of failure occurrence in the work transmission line,
• the node device comprising:
• a first memory section for storing the transmitted signal at the time of normal operation;
• and
• a first read control section for reading out said transmitted signal stored before failure occurrence in said work transmission line, from said first memory section and sending out said transmitted signal through said protection transmission line in the opposite direction, at the time of failure occurrence in said work transmission line, wherein
• said node device is constructed as an add node device that inserts an external signal into said ring network;
• and
• said first read control section is constructed so as to send out said transmitted signal in a direction differing from the direction in which the external signal was inserted before failure occurrence in said work transmission line, at said time of failure occurrence in said work transmission line.

In a hitless path switching ring network node device connected in ring form with one or more node devices through a work transmission line and a protection transmission line wherein at the time of normal operation a signal is transmitted with said work transmission line and at the time of failure occurrence in said work transmission line the signal can be transmitted with said protection transmission line in the opposite direction from the direction in which the signal was transmitted before failure occurrence

• in order to cause the signal to be received at another node device without instantaneous hitting of the signal at said time of failure occurrence in said work transmission line,
• the node device comprising:
• a first memory section for storing the transmitted signal at the time of normal operation;
• and
• a first read control section for reading out said transmitted signal stored before failure occurrence in said work transmission line, from said first memory section and sending out said transmitted signal through said protection transmission line in the opposite direction, at the time of failure occurrence in said work transmission line,
• wherein said first memory section and said first read control section are respectively provided for each of a plurality of paths handled by said ring network and are constructed so as to perform sending of said transmitted signal in the unit of said path at the time of failure occurrence in said work transmission line
• said hitless path switching ring network node device further comprising a first path selecting section for selecting a path whose priority order is lower within a previously determined priority order, when sending of said transmitted signal is performed in the unit of said path.

In a hitless path switching ring network node device connected in ring form with one or more node devices through a work transmission line and a protection transmission line wherein at the time of normal operation a signal is transmitted with said work transmission line and at the time of failure occurrence in said work transmission line the signal can be transmitted with said protection transmission line in the opposite direction from the direction in which the signal was transmitted before failure occurrence,

• in order to cause the signal to be received at another node device without
• instantaneous hitting of the signal at said time of failure occurrence in said work transmission line,
• the node device comprising:
• a first memory section for storing the transmitted signal at the time of normal operation, and
• a first read control section for reading out said transmitted signal stored before failure occurrence in said work transmission line, from said first memory section and sending out said transmitted signal through said protection transmission line in said opposite direction, at the time of failure occurrence in said work transmission line,
• wherein said first memory section and said first read control section are respectively provided in the units of some paths of a plurality of paths handled by said ring network and are constructed so as to perform sending of said transmitted signal in the units of said some paths at the time of failure occurrence in said work transmission line
• said hitless path switching ring network node device further comprising a first path selecting section for selecting a path whose priority order is lower within a previously determined priority order, when sending of said transmitted signal is performed in the unit of said path.

In a hitless path switching ring network node device connected in ring form with other one or more node devices through a work transmission line and a protection transmission line wherein at the time of normal operation a signal is transmitted with said work transmission line and at the time of failure occurrence in said work transmission line the signal can be transmitted with said protection transmission line in the same direction as the direction in which the signal was transmitted before failure occurrence in said work transmission line,

• in order to cause the signal to be received at the other node devices without instantaneous hitting of the signal at the time of failure occurrence in said work transmission line,
• the node device comprising:
• a fourth memory section for storing the signal being transmitted onto said work transmission line at said time of normal operation;
• and
• a second read control section for reading out the transmitted signal held from said fourth memory section before failure occurrence in said work transmission line and sending out said transmitted signal through said protection transmission line in said same direction, at the time of failure occurrence in said work transmission line.

In a hitless path switching ring network node device connected in ring form with other one or more node devices through a work transmission line and a protection transmission line wherein at the time of normal operation a signal is transmitted with said work transmission line and at the time of failure occurrence in said work transmission line the signal can be transmitted with said protection transmission line in the opposite direction from the direction in which the signal was transmitted before failure occurrence in said work transmission line,

• in order to receive the signal from said other node device without instantaneous hitting of the signal at the time of failure occurrence in said work transmission line,
• the node device comprising:
• a second memory section for storing the signal received through said work transmission line at said time of normal operation;
• a third memory section for storing the signal received through said protection transmission line from said other node device at the time of failure occurrence in said work transmission line;
• and
• a first phase adjusting section for matching a time phase of the received signal stored in said second memory section after failure occurrence in said work transmission line with a time phase of the received signal stored in said third memory section before failure occurrence in said work transmission line and outputting said received signal to the outside.

In a hitless path switching ring network comprising at least two node devices connected in ring form through a work transmission line and a protection transmission line wherein at the time of normal operation a signal is transmitted with said work transmission line and at the time of failure occurrence in said work transmission line the signal can be transmitted with said protection transmission line in the opposite direction from the direction in which the signal was transmitted before failure occurrence in said work transmission line,

• in order to cause the signal to be received at the other of said node devices without instantaneous hitting of the signal at the time of failure occurrence in said work transmission line,
• a failure occurrence-time hitless path switching transmission method in the ring network wherein
• at the time of failure occurrence in said work transmission line, one node device of said node devices, which is transmitting the signal in a direction in which failure occurred, retransmits the signal held before failure occurrence in said work transmission line through said protection transmission line in said opposite direction;
• and
• said other node device matches a time phase of the signal received through said work transmission line after failure occurrence in said work transmission line with a time phase of the received signal before failure occurrence in said work transmission line retransmitted through said protection transmission line from said one node device and outputs said received signal to the outside.