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 establishing an optical connection between a first terminal switching node and a second terminal switching node along a path in an optical network, the path including at least one intermediate switching node, the method comprising:
 sending a connection request communication from the first terminal switching node along the path;   at each intermediate switching node along the path from the first terminal switching node to the second terminal switching node:
 receiving the connection request communication request from a previous switching node along the path, 
 responsive to the connection request communication, identifying an optical channel that is available on a link between the previous switching node and the intermediate switching node, and 
 sending a connection request communication to a next switching node along the path; 
   at the second terminal switching node:
 receiving the connection request communication request from a previous switching node along the path, 
 responsive to the connection request, identifying an optical channel that is available on a link between the previous switching node and the second terminal switching node, 
 establishing a connection to the previous switching node along the path using the previously identified available optical channel, and 
 sending a connection confirm communication to the previous switching node along the path; 
   at each intermediate switching node along the path from the second terminal switching node to the first terminal switching node:
 receiving the connection confirm communication from the next switching node along the path, 
 responsive to the connection confirm in communication, establishing a connection to the previous switching node along the path using the previously identified available optical channel, and 
 sending a connection confirm communication to the previous switching node along the path; 
   at the first terminal switching node:
 receiving the connection confirm communication from the next switching node along the path; and 
   completing, establishment of the optical connection.   
     
     
         31 . The method of  claim 30 , wherein each connection request communication comprises a connection request message. 
     
     
         32 . The method of  claim 30 , wherein each connection confirm communication comprises a connection confirm message. 
     
     
         33 . The method of  claim 30 , further comprising:
 storing at the first terminal switching node and at each intermediate switching node along the path the following:
 a routing table identifying a next hop switching node for the path, and 
 an optical channel availability table identifying any communication channels not yet allocated to connections. 
   
     
     
         34 . The method of  claim 33 , wherein each routing table identifies a respective next hop switching node for a respective path between each possible pair of first and second terminal switching nodes. 
     
     
         35 . The method of  claim 34 , wherein each 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.   
     
     
         36 . The method of  claim 30 , wherein at least some of the optical channels are wavelength channels. 
     
     
         37 . The method of  claim 36 , wherein at least some of the optical wavelength channels are optical wavelength channels on a wavelength division multiplexed link. 
     
     
         38 . The method of  claim 30  further comprising:
 at a switching node on the path, sending a connection deny communication to the previous switching node on the path when the switching node cannot identify an optical channel that is available on a link between the switching node and the previous switching node on the path. 
 
     
     
         39 . The method of  claim 30  comprising, at a switching node on the path:
 receiving a connection deny communication from the next switching node on the path; and 
 sending the connection deny communication to the previous switching node on the path. 
 
     
     
         40 . The method of  claim 30 , further comprising:
 receiving a connection initiation communication at the first terminal switching node, wherein the first terminal switching node sends the connection request communication along the path responsive to the connection initiation communication.   
     
     
         41 . The method of  claim 40  further comprising:
 sending a connection deny communication from the first terminal switching node to a source of the connection initiation communication. 
 
     
     
         42 . The method of  claim 41 , further comprising:
 receiving a connection deny communication at the first terminal switching node from the next switching node along the path, wherein the first ten final switching node sends the connection deny communication to the source of the connection initiation communication responsive to the connection deny communication.   
     
     
         43 . The method of  claim 40 , wherein the source of the connection initiation request is customer premises equipment. 
     
     
         44 . The method of  claim 30 , further comprising:
 receiving a connection initiation communication from a source at the first terminal switching node, the connection initiation identifying at least one signal format acceptable to the source; and   sending a connection deny communication from the first terminal switching node to the source of the connection initiation communication when the first terminal switching node cannot confirm that an optical channel having a signal format matching a signal format of the at least one signal format acceptable to the source is available.   
     
     
         45 . An optical communication system comprising a plurality of switching nodes interconnected by optical links, at least two of the switching nodes being adapted to operate as first and second terminal switching nodes and at least one other switching node on a path between the first and second terminal switching nodes being adapted to operate as an intermediate switching node, the terminal switching nodes and the intermediate switching nodes being adapted to cooperate to establish an optical connection between the first terminal switching node and the second terminal switching node along a path comprising the at least one intermediate switching node by:
 sending a connection request communication from the first terminal switching node along the path;   at each intermediate switching node along the path from the first terminal switching node to the second switching node:
 receiving the connection request communication request from a previous switching node along the path, 
 responsive to the connection request communication, identifying an optical channel that is available on a link between the previous switching node and the intermediate switching node, and 
 sending a connection request communication to a next switching node along the path; 
   at the second terminal switching node:
 receiving the connection request communication request from a previous switching node along the path, 
 responsive to the connection request, identifying an optical channel that is available on a link between the previous switching node and the second terminal switching node, 
 establishing a connection to the previous switching node along the path using the previously identified available optical channel, and 
 sending a connection confirm communication to the previous switching node along the path; 
   at each intermediate switching node along the path from the second switching node to the first switching node:
 receiving the connection confirm communication from the next switching node along the path, 
 responsive to the connection confirm communication, establishing a connection to the previous switching node along the path using the previously identified available optical channel, and 
 sending a connection confirm communication to the previous switching node along the path; 
   at the first terminal switching node:
 receiving the connection confirm communication from the next switching node along the path; and 
   completing establishment of the optical connection.   
     
     
         46 . The system of  claim 45 , wherein each connection request communication comprises a connection request message. 
     
     
         47 . The system of  claim 45 , wherein each connection confirm communication comprises a connection confirm message. 
     
     
         48 . The system of  claim 45 , wherein the first terminal switching node and each intermediate switching node along the path is adapted to store:
 a routing table identifying a next hop switching node for the path; and   an optical channel availability table identifying any communication channels not yet allocated to connections.   
     
     
         49 . The system of  claim 48 , wherein each routing table identifies a respective next hop switching node for a respective path between each possible pair of first and second terminal switching nodes. 
     
     
         50 . The system of  claim 49 , wherein each 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.   
     
     
         51 . The system of  claim 45 , wherein at least some of the optical channels are wavelength channels. 
     
     
         52 . The system of  claim 51 , wherein at least some of the optical wavelength channels are optical wavelength channels on a wavelength division multiplexed link. 
     
     
         53 . The system of  claim 45 , wherein each inter mediate switching node on the path is adapted to send a connection deny communication to the previous switching node on the path when the switching node cannot identify an optical channel that is available on a link between the switching node and the previous switching node on the path. 
     
     
         54 . The system of  claim 45  wherein each intermediate switching node on the path is adapted to:
 receive a connection deny communication from the next switching node on the path; and 
 send the connection deny communication to the previous switching node on the path. 
 
     
     
         55 . The system of  claim 45 , wherein the first terminal switching node is adapted to receive a connection initiation communication and to send the connection request communication along the path responsive to the connection initiation communication. 
     
     
         56 . The system of  claim 55  wherein the first terminal switching node is adapted to send a connection deny communication to a source of the connection initiation communication. 
     
     
         57 . The system of  claim 56 , wherein the first terminal switching node is adapted to receive a connection deny communication from the next switching node along the path and to send the connection deny communication to the source of the connection initiation communication responsive to the connection deny communication. 
     
     
         58 . The system of  claim 55 , wherein the source of the connection initiation request is customer premises equipment. 
     
     
         59 . The system of  claim 45 , wherein the first terminal switching node is adapted to:
 receive a connection initiation communication from a source, the connection initiation identifying at least one signal format acceptable to the source; and   send a connection deny communication to the source of the connection initiation communication when the first terminal switching node cannot confirm that an optical channel having a signal format matching a signal format of the at least one signal format acceptable to the source is available.