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 determining paths through an optical network comprising a plurality of interconnected optical switching nodes, the method comprising, at a switching node of the optical network:
 communicating topology information to neighbouring switching nodes;   receiving topology information from the neighbouring switching nodes;   sending the topology information received from the neighbouring switching nodes to the neighbouring switching nodes;   processing the topology information using a routing algorithm to determine a next hop for each of a plurality of paths through the network, each path comprising a set of optical channels, each optical channel on a respective optical communication link between adjacent switching nodes on the path; and   storing in a routing table, the next hop determined for each of the plurality of paths.   
     
     
         31 . The method of  claim 30 , comprising, at each switching node:
 communicating traffic characteristic information to neighbouring network nodes;   receiving traffic characteristic information from neighbouring network nodes; and   sending the traffic characteristic information received from the neighbouring switching nodes to the neighbouring switching nodes.   
     
     
         32 . The method of  claim 31 , wherein the traffic characteristic information comprises a list of signalling types that are acceptable to each port. 
     
     
         33 . The method of  claim 30 , wherein the topology information is communicated at regular time intervals. 
     
     
         34 . The method of  claim 30 , wherein the traffic characteristic information is communicated at regular time intervals. 
     
     
         35 . The method of  claim 30 , wherein the topology information is communicated when there are topology changes. 
     
     
         36 . The method of  claim 31 , wherein the traffic characteristic information is communicated when there are topology changes. 
     
     
         37 . The method of  claim 30 , wherein the topology information is communicated over an in-band control channel. 
     
     
         38 . The method of  claim 30 , wherein the topology information is communicated over an out-of-band control channel. 
     
     
         39 . The method of  claim 31 , wherein the traffic characteristic information is communicated over an in-band control channel. 
     
     
         40 . The method of  claim 31 , wherein the traffic characteristic information is communicated over an out-of-band control channel. 
     
     
         41 . The method of  claim 30 , wherein the routing algorithm comprises a Dijkstra algorithm. 
     
     
         42 . The method of  claim 30 , wherein the routing algorithm determines a respective path for each pair of switching nodes that comprises a source switching node and a destination switching node. 
     
     
         43 . The method of  claim 30 , wherein each optical channel comprises a wavelength channel operating at respective optical wavelength. 
     
     
         44 . The method of  claim 43 , wherein at least some of the switching nodes comprise wavelength converters operable to convert optical signals from one optical wavelength to another optical wavelength.