# US 6,295,146 B1 · System and method for sharing a spare channel among two or more optical ring networks > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 6,295,146 B1 - Document ID: US6295146B1 - Status: Granted - Kind: B1 - Application number: 09/006,962 - Filed: 1998-01-14 - Granted: 2001-09-25 - Earliest claimed: 1998-01-14 - Assignees: MCI Communications Corporation - Inventors: Sridhar Nathan; John A. Fee - Web page: https://patentgrep.com/patent/US6295146B1 ## CPC - H04Q 11/0062: {Network aspects} - G06F 11/2007: {using redundant communication media} - H04B 10/032: using working and protection systems {(H04J14/0287 takes precedence)} - H04J 3/085: {for ring networks, e.g. SDH/SONET rings, self-healing rings, meashed SDH/SONET networks} - H04J 14/0283: {WDM ring architectures} - H04J 14/0286: {WDM hierarchical architectures} - H04J 14/0295: {Shared protection at the optical channel (1:1, n:m)} - H04L 1/22: using redundant apparatus to increase reliability - H04L 41/0663: Performing the actions predefined by failover planning, e.g. switching to standby network elements - H04Q 2011/0081: {Fault tolerance; Redundancy; Recovery; Reconfigurability} - H04Q 2011/0092: {Ring} - H04Q: SELECTING (switches, relays, selectors H01H; wireless communication networks H04W) - G06F: ELECTRIC DIGITAL DATA PROCESSING (computer systems based on specific computational models G06N) - H04B: TRANSMISSION - H04J: MULTIPLEX COMMUNICATION (transmission in general H04B; peculiar to transmission of digital information H04L5/00; systems for the simultaneous or sequential transmission of more than one television signal H04N7/08; in exchanges H04Q11/00; stereophonic systems H04S) - H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M) ## Abstract A system and method for sharing a spare channel among two or more optical ring networks that have a common span. A first optical cross-connect switch (OCCS) and a first OCCS controller are placed at one end of the span and a second OCCS and OCCS controller are placed at the other end of the span. The first OCCS and the first OCCS controller are coupled to a first ADM from each optical ring, and the second OCCS and the second OCCS controller are coupled to a second ADM from each optical ring. The first OCCS controller receives alarm indications from each ADM that it is coupled to that senses a ring failure. The second OCCS controller receives alarm indications from each ADM that it is coupled to that senses a ring failure. Upon receiving an alarm indication, the first OCCS controller directs the first OCCS to optically couple the ADM that originated the alarm indication to the spare channel, and the second OCCS controller directs the second OCCS to optically couple the ADM that originated the alarm indication to the spare channel. ## Claims ### Claim 1 An optical communications system having a first optical ring network and a second optical ring network, wherein the first optical ring network has a first ring element and a second ring element, and wherein the second optical ring network has a first ring element and second ring element, comprising: a first optical cross-connect switch coupled to a first controller, controller including a first switching table, said first switching table having an event column and an action column, and optically coupled to the first ring element of the first optical ring network and to the first ring element of the second optical ring network, said first controller including first receiving means for receiving failure indications from the first ring element of the first optical ring and from the first ring element of the second optical ring; a second optical cross-connect switch coupled to a second controller optically coupled to the second ring element of the first optical ring network and to the second ring element of the second optical ring network, said second controller including second receiving means for receiving failure indications from the second ring element of the first optical ring and from the second ring element of the second optical ring; and a spare channel optically coupled between said first optical switching unit and said second optical switching unit, wherein the first ring element of the first optical ring transmits a first ring failure indication to said first controller upon the first ring element of the first optical ring sensing a ring failure in the first optical ring, and the second ring element of the first optical ring transmits a second ring failure indication to said second controller upon the second ring element of the first optical ring sensing a ring failure in the first optical ring; said first optical switching unit selectively optically couples one of the first ring element of the first optical ring and the first ring element of the second optical ring to said spare channel; and said second optical switching unit selectively optically couples one of the second ring element of the first optical ring and the second ring element of the second optical ring to said spare channel. ### Claim 2 (depends on 1) The system of claim 1, wherein said first controller consults said first switching table upon receiving said first ring failure indication. ### Claim 3 (depends on 2) The system of claim 2, wherein said first controller sends a command corresponding to an action in said first switching table to said first optical cross-connect switch after consulting said first switching table. ### Claim 4 (depends on 3) The system of claim 3, wherein said second optical switching unit includes a second switching table, said second switching table having an event column and an action column. ### Claim 5 (depends on 4) The system of claim 4, wherein said second controller consults said second switching table upon receiving said second ring failure indication. ### Claim 6 (depends on 5) The system of claim 5, wherein said second controller sends a command corresponding to an action in said second switching table to said second optical cross-connect switch after consulting said second switching table. ### Claim 7 (depends on 1) The system of claim 1, wherein the first ring element of the first optical ring is an add-drop-multiplexer. ### Claim 8 (depends on 1) The system of claim 1, wherein said first optical switching unit sends status information to the first ring element of the first optical ring. ### Claim 9 (depends on 8) The system of claim 8, wherein the first ring element of the first optical ring transmits a switch command to said first optical switching unit when the first ring element of the first optical ring senses a ring failure and when said status information indicates that said spare channel is not optically coupled to the first ring element of the first optical ring. ### Claim 10 (depends on 1) The system of claim 1, wherein said first optical switching unit is connected to said second optical switching unit by an optical link. ### Claim 11 (depends on 10) The system of claim 10, wherein said optical link includes a spare fiber optic cable, said spare fiber optic cable connecting a first port of said first optical switching unit with a first port of said second optical switching unit, wherein said spare fiber optic cable carries said spare channel. ### Claim 12 (depends on 10) The system of claim 10, wherein said optical link includes first and second wavelength division multiplexers (WDMs), wherein said first WDM is connected to said second WDM by a fiber optic cable, said fiber optic cable carrying said spare channel. ### Claim 13 A method for sharing a spare channel between a first and a second optical ring, wherein the first optical ring has a first ring element and a second ring element, the second optical ring has a first ring element and second ring element, the first ring element of the first optical ring and the first ring element of the second optical ring being optically coupled to a first optical cross-connect switch, the second ring element of the first optical ring and the second ring element of the second optical ring being optically coupled to a second optical cross-connect switch, and the spare channel optically coupling the first and second optical cross-connect switches, the method comprising the steps of: (a) receiving a first failure indication from one of the first ring element of the first optical ring and the first ring element of the second optical ring; (b) optically coupling the first ring element of the first optical ring with the spare channel if the first ring element of the first optical ring transmitted the first failure indication including consulting a first switching table and sending a switch command corresponding to an action in said first switching table to the first optical cross-connect switch; (c) optically coupling the first ring element of the second optical ring with the spare channel if the first ring element of the second optical ring transmitted the first failure indication; (d) receiving a second failure indication from one of the second ring element of the first optical ring and the second ring element of the second optical ring; (e) optically coupling the second ring element of the first optical ring with the spare channel if the second ring element of the first optical ring transmitted the second failure indication; and (f) optically coupling the second ring element of the second optical ring with the spare channel if the second ring element of the second optical ring transmitted the second failure indication. ### Claim 14 (depends on 13) The method of claim 13, wherein step (e) includes the steps of consulting a second switching table and sending a switch command corresponding to an action in said second switching table to the second optical cross-connect switch.