Survivable ring transmission system with multiple protection classes

1. A method for operating a transmission system configured as a ring that uses a defined multiplexing scheme and has a plurality of connected nodes with connections in opposite directions around the ring, the method including:

assigning channels for carrying traffic along connections between the nodes according to a plurality of protection classes, wherein at least one of the plurality of protection classes comprises a shared protection scheme; and

assigning channels according to the shared protection scheme by:

selecting M channels c 0 , (c 0 +1), . . . , (c 0 +M−1) out of N available channels and selecting n assignment groupings;

for a first direction around the ring,

assigning selected channels for which (c−c 0 ) mod M/n≦M/2n−1 to working traffic; and

assigning selected channels for which (c−c 0 ) mod M/n>M/2n−1 to protection traffic; and

for a second direction around the ring,

assigning selected channels for which (c−c 0 ) mod M/n>M/2n−1 to working traffic; and

assigning selected channels for which (c−c 0 ) mod M/n≦M/2n−1 to protection traffic.

2. The method recited in claim 1 wherein the transmission system comprises an optical transmission system and the plurality of nodes are connected by optical wavelength connections.

3. The method recited in claim 1 wherein at least one of the plurality of protection classes is preferred over another of the plurality of protection classes.

4. The method recited in claim 1 further comprising propagating traffic over the connections in accordance with the assigned protection classes.

5. The method recited in claim 1 wherein the plurality of protection classes are selected from a group comprising an unprotected-connection scheme, a diverse routing protection scheme, a dedicated protection scheme, and the shared protection scheme.

6. The method recited in claim 1 wherein assigning channels for carrying traffic along connections between the nodes is performed statically.

7. The method recited in claim 1 wherein n=M/2 whereby the protection-traffic channels and working-traffic channels are interleaved in both the first and second directions around the ring.

8. The method recited in claim 7 wherein assigning channels according to the shared protection scheme is performed arbitrarily.

9. The method recited in claim 1 wherein M/n is a natural number.

10. The method recited in claim 1 wherein M/2n is a natural number.

11. The method recited in claim 1 wherein M=2p and p is a natural number.

12. The method recited in claim 1 wherein assigning channels is performed dynamically for a second of the plurality of protection classes.

13. The method recited in claim 12 wherein assigning channels is performed for at least one of the plurality of protection classes on a first-come first-served basis in response to corresponding connection requests.

14. The method recited in claim 12 wherein at least one of the plurality of protection classes is limited to a predetermined number of channels.

15. The method recited in claim 12 wherein, for at least one of the plurality of protection classes, a predetermined number of unassigned channels are reserved for such at least one of the plurality of protection classes.

16. The method recited in claim 12 further comprising releasing a channel assignment in response to clearing a connection using that channel.

17. A ring transmission system comprising:

a plurality of nodes configured as a ring and connected by connections in opposite directions around the ring;

a manager coupled with the plurality of nodes, the manager being configured to assign channels for carrying traffic along the connections according to a plurality of protection classes, wherein at least one of the plurality of protection classes comprises a shared protection scheme; and

the manager is configured to assign channels according to the shared protection scheme by:

selecting M channels c 0 , (c 0 +1), . . . , (c 0 +M−1) out of N available channels and selecting n assignment groupings;

for a first direction around the ring,

assigning selected channels for which (c−c 0 ) mod M/n≦M/2n−1 to working traffic; and

assigning selected channels for which (c−c 0 ) mod M/n>M/2n−1 to protection traffic; and

for a second direction around the ring,

assigning selected channels for which (c−c 0 ) mod M/n>M/2n−1 to working traffic; and

assigning selected channels for which (c−c 0 ) mod M/n≦M/2n−1 to protection traffic.

18. The ring transmission system recited in claim 17 wherein the plurality of protection classes are selected from a group comprising an unprotected-connection scheme, a diverse routing protection scheme, a dedicated protection scheme, and the shared protection scheme.

19. The ring transmission system recited in claim 17 wherein n=M/2 whereby the protection-traffic channels and working-traffic channels are interleaved in both the first and second directions around the ring.

20. The ring transmission system recited in claim 17 wherein the manager is configured to assign the channels dynamically to a second of the plurality of protection classes on a first-come first-served basis in response to corresponding connection requests.

21. The ring transmission system recited in claim 17 wherein the manager is configured to reserve a predetermined number of unassigned channels for at least one of the protection classes.

22. A system for operating a ring transmission system having a plurality of nodes configured as a ring connected by connections in opposite directions around the ring, the system comprising:

a manager configured to assign channels for carrying traffic along the connections according to a plurality of protection classes, wherein at least one of the plurality of protection classes comprises a shared protection scheme;

a controller coupled with the manager and the ring, wherein the controller is configured to propagate signals along traffic paths within the ring in accordance with the assigned channels and protection classes; and

the manager is configured to assign channels according to the shared protection scheme by:

selecting M channels c 0 , (c 0 +1), . . . , (c 0 +M−1) out of N available channels and selecting n assignment groupings;

for a first direction around the ring,

assigning selected channels for which (c−c 0 ) mod M/n≦M/2n−1 to working traffic; and

assigning selected channels for which (c−c 0 ) mod M/n>M/2n−1 to protection traffic; and

for a second direction around the ring,

assigning selected channels for which (c−c 0 ) mod M/n>M/2n−1 to working traffic; and

assigning selected channels for which (c−c 0 ) mod M/n≦M/2n−1 to protection traffic.

23. The system recited in claim 22 wherein the plurality of protection classes are selected from a group comprising an unprotected-connection scheme, a diverse routing protection scheme, a dedicated protection scheme, and the shared protection scheme.

24. The system recited in claim 22 wherein n=M/2 whereby the protection-traffic channels and working-traffic channels are interleaved in both the first and second directions around the ring.

25. The system recited in claim 22 wherein the manager is configured to assign the channels dynamically to a second of the plurality of protection classes on a first-come first-served basis in response to corresponding connection requests.

26. The system recited in claim 22 wherein the manager is configured to reserve a predetermined number of unassigned channels for at least one of the plurality of protection classes.

27. A system for operating a ring transmission system having a plurality of nodes configured as a ring connected by connections in opposite directions around the ring, the system comprising:

means for assigning channels for carrying traffic along the connections according to a plurality of protection classes, wherein at least one of the plurality of protection classes comprises a shared protection scheme;

means for propagating signals along traffic paths within the ring in accordance with the assigned channels and protection classes; and

means for assigning channels is configured to assign the channels according to the shared protection scheme by:

selecting M channels c 0 , (c 0 +1), . . . , (c 0 +M−1) out of N available channels and selecting n assignment groupings;

for a first direction around the ring,

assigning selected channels for which (c−c 0 ) mod M/n≦M/2n−1 to working traffic; and

assigning selected channels for which (c−c 0 ) mod M/n>M/2n−1 to protection traffic; and

for a second direction around the ring,

assigning selected channels for which (c−c 0 ) mod M/n>M/2n−1 to working traffic; and

assigning selected channels for which (c−c 0 ) mod M/n≦M/2n−1 to protection traffic.

28. The system recited in claim 27 wherein the plurality of protection classes are selected from a group comprising an unprotected-connection scheme, a diverse routing protection scheme, a dedicated protection scheme, and the shared protection scheme.

29. The system recited in claim 27 wherein n=M/2 whereby the protection-traffic channels and working-traffic channels are interleaved in both the first and second directions around the ring.

30. The system recited in claim 27 wherein the means for assigning channels is configured to assign the channels dynamically to a second of the plurality of protection classes on a first-come first-served basis in response to corresponding connection requests.