Constrained optical mesh protection for transmission systems

• US 6,643,464 B1
• Filed: 07/07/1999
• Issued: 11/04/2003
• Est. Priority Date: 07/07/1999
• Status: Expired due to Term

• Current Assignee: Ciena Corporation
• Original Assignee: Nortel Networks Limited (Nortel Networks Corporation)
• Inventors: Sparks, Adrian P, Baker, Nigel, Roorda, Peter
• Primary Examiner(s): SWARTHOUT, BRENT
• Application Number:
  US09/349,349
• Time in Patent Office: 1,581 Days
• Field of Search: 359/119, 359/110, 359/124, 359/127, 359/128, 359/166, 340/2.7, 714/4, 370/224, 385/24, 398/50, 398/59, 398/58, 398/45
• US Class Current: 398/59
• CPC Class Codes: H04B 10/032 using working and protection systems H04J14/0287 takes precedence
• CPC Class Codes: H04B 10/27 Arrangements for networking
• CPC Class Codes: H04J 14/0284 WDM mesh architectures
• CPC Class Codes: H04J 14/0294 Dedicated protection at the optical channel (1+1)
• CPC Class Codes: H04J 14/0295 Shared protection at the optical channel (1:1, n:m)

Abstract

To provide improved protection bandwidth efficiency for a fast recovery from a fault in an optical network, a protection ring for sharing between some of the protection paths has a pre-configured route so as to overlap on a given one of the links, with other protection paths or other rings. A selector for the given link selects which of the overlapping secondary paths is allocated to the given link at any time. Thus, two types of sharing of protection paths are combined to achieve more efficient use of protection bandwidth. The link selector can be controlled locally and so can operate more rapidly. The local control, essentially independent of the switches used to set up the secondary path through the network, makes the combination easier to scale to larger, more complex networks than shared rings alone.

Claims

1. An optical network comprising:

a plurality of nodes and a plurality of links between the nodes,

a mesh of working paths provided over the links and nodes,

a plurality of secondary paths provided over the

links and nodes, each secondary path for use in case of a failure in a link or node of a working path associated with such secondary path,

a first shared protection ring being provided for shared use by some of the secondary paths, and being arranged to have a shared link overlapping one or more of the secondary paths and

a link selector at each end of the shared link to select which of the first shared protection ring or one of said one or more secondary paths overlapping the shared link is allocated to the shared link detection of a failure in a link or node of a working path associated with said first shared protection ring or said one or more of the secondary paths, said link selectors being controlled independently of said shared protection ring.

2. The network of claim 1, wherein any overlapping secondary paths and any overlapping shared rings are arranged such that any two of them do not overlap more than once with each other.

3. The network of claim 1, wherein the first shared protection ring comprises a first optical switch for coupling one or more of the secondary paths to the first shared protection ring, the optical switch being located adjacent to the link selector, on the first shared protection ring.

4. The network of claim 1 further comprising a transponder, at least part of the transponder being located on a link side of the link selector.

5. The network of claim 1 further comprising a first optical switch for coupling one or more of the secondary paths to the first shared protection ring, the optical switch being located adjacent to the link selector, on the first shared protection ring, and a transponder for converting optical wavelength, to launch an optical signal onto the first shared protection ring, the transponder being located on the coupled secondary path before this path enters the first shared protection ring.

6. The network of claim 1, wherein the one or more secondary paths routed to overlap on the shared link use a second shared protection ring which overlaps on the shared link with the first shared protection ring.

7. The network of claim 1, wherein the link selector is controllable on the basis of levels of priority of different secondary paths.

8. The network of claim 1 further comprising a signalling arrangement provided between the link selector and a node at the far end of the shared link so that the same one of the overlapping secondary paths is selected at both ends of the shared link.

9. A node for use in the network of claim 1, wherein at one end of the shared link, the node comprises the link selector for selecting which of the secondary paths routed to overlap on the shared link is allocated to the shared link on detection of a failure.

10. A node for use in claim 1 or claim 9, wherein, at another end of the shared link, the node comprises a further link selector for the shared link for selecting which of the overlapping secondary paths is allocated to the shared link, the further link selector being arranged to receive an indication of the selection of the link selector at the other end of the shared link, and being arranged to make the same selection.

11. A link selector for use in the node of claim 9, for selecting which of the secondary. paths routed to overlap on the shared link is allocated to the shared link on detection of a failure.

12. A controller for controlling the link selector of claim 11, comprising circuitry for receiving an indication of which of the overlapping secondary paths is being used, determining which is first to be in use and controlling the link selector on the basis of which secondary path is first in use.

13. A method of transmitting data traffic over a working path of the network of claim 1.

14. The method of claim 13, the working path having an associated secondary path which is routed via one of the link selectors.

15. The method of claim 14 comprising the step of switching the data traffic from the working path to the associated secondary path.

16. Software for managing the optical network of claim 1 to provide a data transmission service.

17. Software for determining a configuration of secondary paths in the network of claim 1, such that any two of them overlap over only a single one of the links, and otherwise are routed over separate links so that no two secondary paths share more than one of the links.

18. A node for use in an optical network, the network comprising a number of other nodes and a plurality of links between the nodes, a mesh of working paths provided over the links and nodes, a plurality of secondary paths provided over the links and nodes, each secondary path for use in case of a failure in a link or node of a working path-associated with such secondary path, some of the secondary paths having pre-determined routing so as to overlap on a shared link of a first shared protection ring, the node being for use at one end of the shared link, and comprising:

a selector for the shared link to select which of the first shared protection ring or one of secondary paths routed to overlap on the shared link is allocated to the shared link on detection of a failure in a link or node of a working path associated with said first shared protection ring or said one or more of the secondary paths, said link selector being controlled independently of said shared protection ring.