Optical communication system having ring-based restoration using shared protect links
View Patent ↗In an optical communication system, optical communications are transferred over a first ring and a second ring. A fault is detected on the first ring or the second ring. If the fault is detected on the first ring, a shared optical protect link is used for ring-based restoration of the first ring if the link is available, and restoration overhead for the first ring is transferred in an active location of the shared optical protect link. If the fault is detected on the second ring, the shared optical protect link is used for ring-based restoration of the second ring if the link is available, and restoration overhead for the second ring is transferred in the active location of the shared optical protect link.
1. An optical communication system comprising:
a shared optical protect link; and
an optical node, the optical node configured:
to transfer first optical communications over a first optical ring and to transfer second optical communications over a second optical ring;
to detect a first fault occurring on the first optical ring;
to detect a second fault occurring on the second optical ring;
to determine if the shared optical protect link available for restoration for the first optical ring or for the second optical ring; and
if the first fault is detected and if the shared optical protect link is available for restoration for the first optical ring, to transfer a first restoration overhead from a first signal of the shared optical protect link to an active location of the shared optical protect link, to transfer the first restoration overhead in the active location of the shared optical protect link to indicate that the first optical ring is using the shared optical protect link for ring-based restoration, and to transfer the first optical communications over the shared optical protect link; and
if the second fault is detected and if the shared optical protect link is available for restoration for the second optical ring, to transfer a second restoration overhead from a second signal of the shared optical protect link to the active location of the shared optical protect link, to transfer second restoration overhead in the active location of the shared optical protect link to indicate that the second optical ring is using the shared optical protect link for ring-based restoration, and to transfer the second optical communications over the shared optical protect link.
2. The optical communication system of claim 1 wherein the optical node is further configured not to use the shared optical protect link to simultaneously restore the first optical ring and the second optical ring.
3. The optical communication system of claim 1 wherein the optical node comprises a Synchronous Optical Network (SONET) Add/Drop Multiplexer (ADM).
4. The optical communication system of claim 1 wherein the optical node comprises a digital cross-connect.
5. The optical communication system of claim 1 wherein the active location comprises the overhead portion of a first STS-1 on the shared optical protect link.
6. The optical communication system of claim 1 wherein the active location comprises the Line Overhead (LOH) of a first STS-1 on the shared optical protect link.
7. The optical communication system of claim 1 wherein the active location comprises K1/K2 bytes in a Line Overhead (LOH) of a first STS-1 on the shared optical protect link.
8. The optical communication system of claim 1 wherein the optical node comprises a Synchronous Optical Network (SONET) Add/Drop Multiplexer (ADM) and a digital cross-connect and wherein the SONET ADM and the digital cross-connect communicate over a SONET Data Communication Channel (DCC) to perform the ring-based restoration.
9. The optical communication system of claim 1 wherein the optical node is configured to initiate mesh-based restoration for the first ring if the shared optical protect link is not available for restoration for the first optical ring when the first fault is detected on the first optical ring, and to initiate mesh-based restoration for the second ring if the shared optical protect link is not available for restoration for the second optical ring when the second fault is detected on the second optical ring.
10. The optical communication system of claim 1 wherein the first ring and the second ring each comprise a four fiber bidirectional line switched ring, and wherein the shared optical protect link comprises a shared protect line.
11. A method of operating an optical communication system, the method comprising:
transferring first optical communications over a first optical ring and transferring second optical communications over a second optical ring;
detecting a fault on one of the first optical ring and the second optical ring;
if the fault is detected on the first optical ring, determining if a shared optical protect link is available for restoration for the first optical ring, and if the shared optical protect link is available for restoration for the first optical ring, transferring a first restoration overhead from a first signal of the shared optical protect link to an active location of the shared optical protect link, transferring the first restoration overhead in the active location of the shared optical protect link to indicate that the first optical ring is using the shared optical protect link for ring-based restoration, and transferring the first optical communications over the shared optical protect link and; and
if the fault is detected on the second ring, determining if the shared optical protect link is available for restoration for the second optical ring, and if the shared optical protect link is available for restoration for the second optical ring, transferring a second restoration overhead from a second signal of the shared optical protect link to an active location of the shared optical protect link, transferring the second restoration overhead in the active location of the shared optical protect link to indicate that the second optical ring is using the shared optical protect link for ring-based restoration, and transferring the second optical communications over the shared optical protect link.
12. The method of claim 11 the shared optical protect link is not used to simultaneously restore the first optical ring and the second optical ring.
13. The method of claim 11 wherein transferring the first optical communications and the second optical communications comprises using a Synchronous Optical Network (SONET) Add/Drop Multiplexer (ADM).
14. The method of claim 11 wherein transferring the first optical communications and the second optical communications comprises using a digital cross-connect.
15. The method of claim 11 wherein the active location comprises the overhead portion of a first STS-1 on the shared optical protect link.
16. The method of claim 11 wherein the active location comprises the Line Overhead (LOH) of a first STS-1 on the shared optical protect link.
17. The method of claim 11 wherein the active location comprises K1/K2 bytes in a Line Overhead (LOH) of a first STS-1 on the shared optical protect link.
18. The method of claim 11 wherein transferring the first optical communications or the second optical communications over the shared optical protect link comprises communicating between a Synchronous Optical Network (SONET) Add/Drop Multiplexer (ADM) and a digital cross-connect over a SONET Data Communication Channel (DCC) to perform the ring-based restoration.
19. The method of claim 11 further comprising initiating mesh-based restoration for the first ring if the shared optical protect link is not available for restoration for the first optical ring when the fault is detected on the first optical ring, and initiating mesh-based restoration for the second ring if the shared optical protect link is not available for restoration for the second optical ring when the fault is detected on the second optical ring.
20. The method of claim 11 wherein the first ring and the second ring each comprise a four fiber bidirectional line switched ring, and wherein the shared optical protect link comprises a shared protect line.