Fault restoration control method and it's apparatus in a communication network

A method of restoration from a fault in a communication network, said communication network being formed by interconnecting a plurality of nodes via a plurality of transmission lines using optical fibers, said plurality of nodes including at least one set of node equipment including a line terminal equipment and an optical cross-connect equipment, said method comprising the steps of:

• causing a line terminal equipment of said at least one set of node equipment to terminate Synchronous Digital Hierarchy (SDH) to detect a fault in an optical fiber under communication, and in response to the detected fault, give a command functioning as a trigger for optical fiber change-over to an optical cross-connect equipment included in the node equipment;
• and
• causing said optical cross-connect equipment given said command functioning as the trigger to exchange change-over control information indicating optical switch setting situation between said optical cross-connect equipment given said command and optical cross-connect equipments included in other node equipments, and form a restoration route,
• wherein said step of causing said optical cross-connect equipment to exchange change-over control information and form a restoration route comprises the step of causing said optical cross-connect equipment to collect node information indicating whether a change-over route is usable from optical cross-connect equipments included in other node equipments, and determine a restoration route based on said node information,
• wherein said command functioning as the trigger for optical fiber change-over comprises contents of protection switching bytes of an overhead signal of the SDH, and
• wherein said exchange of change-over control information is conducted by using an optical signal having a wavelength different from a normal wavelength used by said optical cross-connect equipments.

A method of restoration from a fault in a communication network, said communication network being formed by interconnecting a plurality of nodes via a plurality of transmission lines using optical fibers, said plurality of nodes including at least one set of node equipment including a line terminal equipment and an optical cross-connect equipment, said method comprising the steps of:

• causing a line terminal equipment of said at least one set of node equipment to terminate Synchronous Digital Hierarchy (SDH) to detect a fault in an optical fiber under communication, and in response to the detected fault, give a command functioning as a trigger for optical fiber change-over to an optical cross-connect equipment included in the node equipment;
• and
• causing said optical cross-connect equipment given said command functioning as the trigger to exchange change-over control information indicating optical switch setting situation between said optical cross-connect equipment given said command and optical cross-connect equipments included in other node equipments, and form a restoration route,
• wherein said step of causing said optical cross-connect equipment to exchange change-over control information and form a restoration route comprises the step of causing said optical cross-connect equipment to collect node information indicating whether a change-over route is usable from optical cross-connect equipments included in other node equipments, and determine a restoration route based on said node information,
• wherein said step of causing said optical cross-connect equipment to exchange change-over control information and form a restoration route comprises the step of causing said optical cross-connect equipment to request each of optical cross-connect equipments included in specific node equipments concerning said determined restoration route to change-over one transmission line using an optical fiber to another,
• wherein said command functioning as the trigger for optical switching bytes of an overhead signal of the SDH, and
• wherein said exchange of change-over control information is conducted by using an optical signal having a wavelength different from a normal wavelength used by said optical cross-connect equipments.

A method for restoration from a fault in a communication network, said communication network being formed by interconnecting a plurality of nodes via a plurality of transmission lines using optical fibers, said plurality of transmission lines using optical fibers including a protection system, said plurality of nodes including at least one set of node equipment including a line terminal equipment and an optical cross-connect equipment, said method comprising the steps of:

• causing said line terminal equipment to terminate Synchronous Digital Hierarchy (SDH) to detect a fault in an optical fiber under communication, and, in response to the detected fault, inform an optical cross-connect equipment included in its own node equipment of the occurrence of the fault, and determine whether a change-over to the protection system should be conducted or a change-over to a restoration route passing through another node equipment should be conducted;
• causing said informed optical cross-connect equipment to exchange change-over control information between said informed optical cross-connect equipment and optical cross-connect equipments included in other node equipments, and determine a restoration route provisionally;
• when said line terminal equipment has decided that a change-over to a restoration route passing through another node equipment should be conducted, causing said line terminal equipment to give a command functioning as trigger for optical fiber change-over to said optical cross-connect equipment included in its own node equipment;
• and
• causing said optical cross-connect equipment given said command to form a transmission line using said provisionally determined restoration route,
• wherein said command functioning as a trigger for optical fiber change-over comprises contents of protection switching bytes of an overhead signal of the SDH, and
• wherein said exchange of change-over control information is conducted by using an optical signal having a wavelength different from a normal wavelength used by said optical cross-connect equipments.

A communication network apparatus being formed by interconnecting a plurality of nodes via a plurality of transmission lines using optical fibers, each node of said plurality of nodes includes at least one set of node equipment including a line terminal equipment and an optical cross-connect equipment,

• wherein said optical cross-connect equipment in said one set of node equipment, comprises:
• a communication controller connected to cross-connect equipment of other nodes for conducting communication between said node and other nodes,
• an equipment node information sending portion, connected to said communication controller, for conducting check of optical fibers connected to said node,
• another node OXC change-over request section, connected to said communication controller, for requesting other nodes to change-over switches according to a determined route by exchanging change-over control information between said optical cross-connect equipment of said node and optical cross-connect equipment of the other nodes,
• another node information collector, connected to said communication controller, for collecting node information concerned with operation state of an optical fiber,
• a change-over trigger acceptor, connected to said communication controller, for informing each component that a change-over trigger has occurred to start cross-connect,
• an optical switch controller, connected to said communication controller, for controlling optical switches, and
• a change over route determining section, connected to said communication controller, for determining a shortest usable route,
• wherein said exchange of change-over control information is conducted by using an optical signal having a wavelength different from a normal wavelength used by said optical cross-connect equipments,
• wherein said line terminal equipment in said one set of node equipment, comprises:
• a communication controller for performing communication between said optical cross-connect equipment of said node,
• a change-over trigger generator, connected to said communication controller, for terminating Synchronous Digital Hierarchy (SDH) for detecting a fault and generating a trigger for causing a change-over by said optical cross-connect equipment, and
• a fault detector, connected to said change-over trigger generator, for detecting a fault of an optical fiber of an active system,
• wherein said trigger comprises contents of protection switching bytes of an overhead signal of the SDH.