Ring network including at least one subtending ring originating and terminating at a central-office node

Abstract

In a WDM optical communication system that includes a plurality of nodes interconnected by communication links, a node is provided which includes an optical coupling arrangement having at least one input port for receiving a WDM signal and a plurality of output ports for selectively receiving one or more wavelength components of the WDM optical signal. The optical coupling arrangement is adaptable to reconfigure its operational state to (i) selectively direct any one of the wavelength components received on the input port to any of the output ports independently of any other of the wavelength components and (ii) selectively direct any combination of two or more of the wavelength components from the input port to at least two of the output ports that serve as WDM output ports. At least one optical WDM interface is optically coupled to a first of the WDM output ports. The optical WDM interface is adapted to receive, at different times, a transponder and a transmission link through which a WDM signal can be communicated. At least one transponder is coupled to a second of the WDM output ports.

1 - 4 . (canceled) 
     
     
         5 . A ring network, comprising:
 a plurality of nodes connected by optical fiber in sequence along a looped transmission path, the plurality of nodes including a central-office node; and   a first subtending ring that originates and terminates at the central-office node, the first subtending ring configured to aggregate first local traffic via a first plurality of network nodes disposed along the first subtending ring and couple the first local traffic onto the transmission path without converting the first local traffic to or from an electrical signal.   
     
     
         6 . The ring network of  claim 5 , the central-office node including a first reconfigurable switch configured to direct light at a first selectable channel wavelength from the looped transmission path to the first subtending ring, so that the first subtending ring originates at the first reconfigurable switch. 
     
     
         7 . The ring network of  claim 6 , the central-office node further including a second reconfigurable switch configured to direct light at the first selectable channel wavelength from the first subtending ring to the looped transmission path, so that the first subtending ring terminates at the second reconfigurable switch. 
     
     
         8 . The ring network of  claim 7 , further comprising a second subtending ring that originates and terminates at the central-office node, the second subtending ring configured to aggregate second local traffic via a second plurality of network nodes disposed along the second subtending ring and couple the second local traffic onto the transmission path without converting the second local traffic to or from an electrical signal. 
     
     
         9 . The ring network of  claim 8 , wherein the first reconfigurable switch is further configured to direct light at a second selectable channel wavelength, different from the first selectable channel wavelength, from the looped transmission path to the second subtending ring, so that the second subtending ring originates at the first reconfigurable switch. 
     
     
         10 . The ring network of  claim 9 , wherein the second reconfigurable switch is further configured to direct light at the second selectable channel wavelength from the second subtending ring to the looped transmission path, so that the second subtending ring terminates at the second reconfigurable switch. 
     
     
         11 . The ring network of  claim 10 , wherein the first and second selectable channel wavelengths each comprise a different one of a plurality of predefined channel wavelengths. 
     
     
         12 . The ring network of  claim 5 , wherein the transmission path transmits in only one direction. 
     
     
         13 . The ring network of  claim 5 , wherein the transmission path is bi-directional. 
     
     
         14 . A ring network, comprising:
 a plurality of nodes connected by optical fiber in sequence along a looped transmission path, the plurality of nodes including a central-office node; and   first and second subtending rings that each originate and terminate at the central-office node, each of the first and second subtending rings configured to aggregate local traffic via a respective plurality of network nodes disposed along the respective subtending ring and couple the local traffic onto the transmission path without converting the local traffic to or from an electrical signal.   
     
     
         15 . The ring network of  claim 14 , further comprising a first reconfigurable switch configured to simultaneously:
 direct light at a first selectable channel wavelength from the looped transmission path to the first subtending ring; and   direct light at a second selectable channel wavelength, different from the first selectable channel wavelength, from the looped transmission path to the second subtending ring.   
     
     
         16 . The ring network of  claim 15 , further comprising a second reconfigurable switch configured to simultaneously:
 direct light at the first selectable channel wavelength from the first subtending ring to the looped transmission path; and   direct light at the second selectable channel wavelength from the second subtending ring to the looped transmission path.   
     
     
         17 . The ring network of  claim 15 , wherein the first and second selectable channel wavelengths each comprise a different one of a plurality of predefined channel wavelengths. 
     
     
         18 . The ring network of  claim 14 , wherein the transmission path transmits in only one direction. 
     
     
         19 . The ring network of  claim 14 , wherein the transmission path is bi-directional. 
     
     
         20 . A ring network, comprising:
 a plurality of nodes connected by optical fiber in sequence along a looped transmission path, the plurality of nodes including a central-office node;   the central-office node including a first reconfigurable switch configured to direct light at a plurality of selectable channel wavelengths from the looped transmission path to a respective plurality of subtending rings, so that each of the plurality of subtending rings originates at the first reconfigurable switch; and   the central-office node further including a second reconfigurable switch configured to direct light at the plurality of selectable channel wavelengths from the respective plurality of subtending rings to the looped transmission path, so that each of the plurality of subtending rings terminates at the second reconfigurable switch;   wherein each of the plurality of subtending rings is configured to aggregate local traffic via a respective plurality of network nodes disposed along the respective subtending ring and couple the local traffic onto the transmission path without converting the local traffic to or from an electrical signal.   
     
     
         21 . The ring network of  claim 20 , wherein each of the plurality of selectable channel wavelengths comprises a different one of a plurality of predefined channel wavelengths. 
     
     
         22 . The ring network of  claim 20 , wherein the transmission path transmits in only one direction. 
     
     
         23 . The ring network of  claim 20 , wherein the transmission path is bi-directional.