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 (ND) 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 an intermediate switching node adapted to establish an optical connection between first and second terminal switching nodes in an optical network, the network comprising the first and second terminal switching nodes and a plurality of other switching nodes interconnected by optical links, the intermediate switching node being connected to a respective ingress link and a respective egress link in a path comprising a set of optical channels identified for carrying optical signals between the first and second terminal switching nodes via the intermediate switching node, the method comprising:
 switching optical signals arriving on the respective ingress link to the respective egress link at the intermediate switching node.   
     
     
         31 . The method of  claim 30 , wherein the intermediate switching node switches optical signals arriving on the respective ingress link to the respective egress link by switching optical signals from an ingress optical channel on the ingress link to an egress optical channel on the egress link. 
     
     
         32 . The method of  claim 31 , wherein the egress optical channel is the same as the ingress optical channel. 
     
     
         33 . The method of  claim 31 , wherein the egress optical channel differs from the ingress optical channel. 
     
     
         34 . The method of  claim 30 , wherein a plurality of wavelength division multiplexed wavelength channels is carried on at least one of the optical links. 
     
     
         35 . The method of  claim 34 , wherein the identified path is a path comprising a set of wavelength channels on the optical links for carrying optical signals between the first and second terminal nodes. 
     
     
         36 . The method of  claim 35 , wherein the intermediate switching node switches optical signals arriving on the respective ingress link to the respective egress link by switching optical signals from an ingress wavelength channel on the ingress link to an egress wavelength channel on the egress link. 
     
     
         37 . The method of  claim 36 , wherein the egress wavelength channel is the same as the ingress wavelength channel. 
     
     
         38 . The method of  claim 36 , wherein the egress wavelength channel differs from the ingress wavelength channel, and switching optical signals arriving on the ingress link to the respective egress link comprises converting the optical signals from the ingress wavelength to the egress wavelength. 
     
     
         39 . The method of  claim 30 , comprising participating in identifying a path by:
 a) associating a respective next hop switching node with every possible pair of source and destination switching nodes;   b) receiving a connection request communication associated with the first and second terminal switching nodes from another switching node; and   c) upon receipt of the connection request communication, reserving an optical channel on the link connecting the intermediate switching node to the other switching node which sent the connection request communication.   
     
     
         40 . The method of  claim 39 , wherein associating a respective next hop switching node with every possible pair of source and destination switching nodes comprises executing a routing algorithm based on topology information about the network. 
     
     
         41 . The method of  claim 40 , comprising exchanging the topology information among the switching nodes using a control channel. 
     
     
         42 . The method of  claim 41 , wherein the control channel is an in-band control channel. 
     
     
         43 . The method of  claim 41 , wherein the control channel is an out-of-band control channel occupying at least one optical channel along each link. 
     
     
         44 . The method of  claim 39 , wherein the intermediate switching node is adapted to switch the optical signals by:
 if the intermediate switching node is connected to the second terminal switching node: switching the optical signal occupying the reserved optical channel on the respective ingress link over to the reserved optical channel on the respective egress link and forwarding a connection confirmation communication to the switching node connected to the ingress link; and   if the intermediate switching node is not connected to the second terminal switching node: upon receipt of a connection confirmation communication, switching the optical signal occupying the reserved optical channel on the respective ingress link over to the reserved optical channel on the respective egress link and forwarding a connection confirmation communication to the switching node connected to the ingress link.   
     
     
         45 . The method of  claim 30 , wherein the optical connection is a bidirectional optical connection. 
     
     
         46 . The method of  claim 45 , comprising:
 identifying a path comprising a set of optical channels on the optical links for carrying optical signals between the first and second terminal switching nodes via at least one intermediate switching node by identifying a set of optical channels on the optical links for carrying optical signals from the first terminal switching node to the second terminal switching node and a set of optical channels for carrying signals from the second terminal switching node to the first terminal switching node; and   switching optical signals arriving on a respective first link to a respective second link and to switch optical signals arriving on the respective second link to the respective first link wherein the intermediate node is connected between the first link and the second link.