Optical switch and protocols for use therewith

Abstract

A method of establishing a data connection between terminal switching nodes in a network 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. Switching nodes participate 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. 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 establishing a connection along a path between a source node and a destination node in a switched optical network, the switched optical network comprising a plurality of optical switching nodes interconnected by optical links, the method comprising:
 determining a path through the network from the source node through an intermediate optical switching node to the destination node, the intermediate optical switching node having a wavelength converter; and   setting up the connection along the path node by node, each node communicating a wavelength associated with the connection at the node to at least one neighbouring node on the path, the connection being made through the wavelength converter at the intermediate optical switching node when the wavelength communicated to the intermediate optical switching node is different from the wavelength associated with the connection at the intermediate optical switching node.   
     
     
         31 . The method of  claim 30 , wherein:
 the intermediate optical switching node has plural wavelength converters; and   the connection is made through a selected one of the plural wavelength converters when the wavelength communicated to the intermediate optical switching node is different from the wavelength associated with the connection at the intermediate optical switching node.   
     
     
         32 . The method of  claim 30 , wherein:
 the path extends through plural intermediate optical switching nodes, each having a wavelength converter; and   the connection is made through a respective wavelength converter at each of intermediate optical switching nodes where the wavelength communicated to the intermediate optical switching node is different from the wavelength associated with the connection at the intermediate optical switching node.   
     
     
         33 . The method of  claim 30 , wherein:
 wavelengths available for the connection are reserved node by node in one direction along the path; and   the connection is set up using the reserved wavelengths node by node in the other direction along the path.   
     
     
         34 . The method of  claim 33 , wherein:
 the wavelengths are reserved node by node from the source node to the destination node; and   the connection is set up using the reserved wavelengths node by node from the destination node to the source node.   
     
     
         35 . The method of  claim 30 , wherein each node communicates the wavelength associated with the connection at the node to at least one neighbouring node on the path using a network layer protocol. 
     
     
         36 . The method of  claim 35 , wherein the network layer protocol uses an in-band control channel. 
     
     
         37 . The method of  claim 35 , wherein the network layer protocol uses an out-of-band control channel. 
     
     
         38 . The method of  claim 35 , wherein the network layer protocol uses a connection confirmation message to communicate the wavelength associated with the connection at a node to a neighbouring node on the path. 
     
     
         39 . The method of  claim 35 , wherein the network layer protocol uses a connection request message to request a connection through a node. 
     
     
         40 . The method of  claim 39 , wherein a connection request message is sent to a neighbouring node on the path only when an available wavelength has been reserved for the connection at the node sending the connection request message. 
     
     
         41 . The method of  claim 35 , wherein the network layer protocol uses a connection denial message to indicate that no wavelength is available at a node on the path. 
     
     
         42 . The method of  claim 41 , wherein the connection denial message is sent from the node having no available wavelength along the path toward the source node. 
     
     
         43 . The method of  claim 30 , comprising:
 transmitting on the path from the source node toward the destination an optical signal at the wavelength associated with the connection at the source node;   optically switching the optical signal at each intermediate node where the wavelength associated with the connection does not change;   converting the optical signal to the wavelength associated with connection at each intermediate node where the intermediate node associates a different wavelength to the connection and transmitting the converted optical signal on the path toward the destination node;   until the optical signal reaches the destination node.   
     
     
         44 . The method of  claim 30 , wherein determining a path extending between the source node and the destination node comprises associating a respective next hop node with every possible combination of a source node and a destination node at each node of the switched optical network. 
     
     
         45 . The method of  claim 44 , wherein associating a respective next hop node with every possible combination of a source node and a destination node comprises executing a routing algorithm based on topology information characterizing the switched optical network. 
     
     
         46 . The method of  claim 45 , comprising exchanging the topology information among the nodes of the switched optical network using a control channel. 
     
     
         47 . The method of  claim 46 , wherein the control channel is an in-band control channel. 
     
     
         48 . The method of  claim 46 , wherein the control channel is an out-of-band control channel. 
     
     
         49 . The method of  claim 48 , wherein the out-of-band control channel occupies at least one wavelength on each link.