Optical switch and protocols for use therewith

Abstract

A method of establishing a data connection between terminal switching nodes in a network and switching nodes for implementing the method. The method involves switching nodes participating in a network layer wavelength routing (WR) protocol to determine the next hop switching node for every possible combination of terminal nodes based on the network topology. The method also involves the switching nodes participating in a network layer wavelength distribution (WD) once the data connection is to be established. The WR protocol determines the path used through the network, while the WD protocol assigns wavelengths on each link between switching nodes. The wavelengths may be different on different optical links. The switching nodes include wavelength converters with an optical switch or optoelectronic converters with a digital electronic switch. A digital electronic switch can also provide signal reformatting. Advantages of using potentially different wavelengths along various segments of a single end-to-end connection yields increased wavelength efficiency.

1 .- 29 . (canceled) 
     
     
         30 . A method of operating a switching node to establish an optical connection between a first terminal switching node and a second terminal switching node along a path in an optical network, responsive to a connection initiation communication sent to the first terminal switching node upon requesting the connection, the method comprising:
 receiving a communication from an adjacent switching node along the path;   if the communication is a connection request communication received from a previous switching node along the path, then:
 identifying an optical channel that is available on a link between the current switching node and the previous switching node; and 
 if the switching node is not the second terminal switching node, forwarding the connection request communication to the next switching node along the path; and 
   if the communication is a connection confirm communication received from a next switching node along the path, then if the current switching node is not the first terminal switching node:
 establishing a connection to the previous switching node along the path using the previously identified available communication channel; and 
 sending a connection confirm communication to the previous switching node along the path. 
   
     
     
         31 . The method of  claim 30 , comprising:
 establishing a connection using the previously identified optical channel and sending a connection confirm communication to the previous switching node if the communication is a connection request communication and if the switching node is the second terminal switching node.   
     
     
         32 . The method of  claim 30 , wherein each connection request communication comprises a connection request message. 
     
     
         33 . The method node of  claim 30 , wherein each connection confirm communication comprises a connection confirm message. 
     
     
         34 . The method of  claim 30 , comprising:
 storing a routing table identifying a next hop switching node for the path; and   storing an optical channel availability table identifying any optical channels not yet allocated to connections.   
     
     
         35 . The method of  claim 34 , wherein the routing table identifies a respective next hop switching node for a respective path between each possible pair of first and second terminal switching nodes. 
     
     
         36 . The method of  claim 34 , wherein the optical channel availability table identifies for each port of the switching node:
 an adjacent switching node connected to that port;   optical channels provided on that port; and   whether each optical channel provided on that port is currently occupied or currently available.   
     
     
         37 . The method of  claim 30 , wherein the optical channel is an optical wavelength channel. 
     
     
         38 . The method of  claim 37 , wherein the optical wavelength channel is an optical wavelength channel on a wavelength division multiplexed link. 
     
     
         39 . The method of  claim 30 , comprising:
 sending a connection deny communication to the previous switching node when the current switching node cannot identify an optical channel that is available on a link between the current switching node and the previous switching node.   
     
     
         40 . The method of  claim 30 , comprising:
 sending a connection deny communication to the previous switching node when the communication is a connection deny message and the current switching node is not the first terminal switching node.   
     
     
         41 . The method of  claim 30 , comprising:
 sending a connection deny communication to a source of the connection initiation request when the communication is a connection deny communication and the current switching node is the first terminal switching node.   
     
     
         42 . The method of  claim 30 , comprising:
 sending a communication deny communication to customer premises equipment that sent the connection initiation request when the communication is a connection deny communication and the current switching node is the first terminal switching node.   
     
     
         43 . The method of  claim 30 , comprising:
 sending a connection deny communication to the source when the communication is a connection initiation communication received from a source, the connection initiation communication identifies at least one acceptable signal format, the current switching node is the first terminal switching node and the first terminal switching node cannot confirm that a channel having a signal format matching at least one signal format of the at least one acceptable signal format is available.