Network restoration under dual failures using path protecting preconfigured cycles

A method for designing a survivable optical network that provides end-to-end path restoration to a plurality of demands in the event of a single link or node failure and to a plurality of demands in the event of any two such failures using a plurality of path protecting preconfigured cycles, where in the event of the first or second failure each of the affected demands is rerouted onto a single preconfigured restoration route on a segment of a cycle using pre-specified restoration wavelengths without resorting to intermediate switching or wavelength conversions on the restoration route, comprising the steps of:

• a. providing an optical network comprising a plurality of nodes connected by links forming paths;
• b. generating a plurality of candidate path protecting preconfigured cycles where each of the preconfigured cycles protect some assigned demands from two failures and some assigned demands from a single failure;
• c. generating additional plurality of candidate path protecting preconfigured cycles where each of the preconfigured cycles is generated by using known methods to assign demands that require protection from any single failure, resulting in a path protecting preconfigured cycle that protects all assigned demands from a single failure;
• d. selecting a set of path protecting preconfigured cycles from among all candidate preconfigured cycles so that each of the demands is protected by a single cycle while achieving a near-minimum total restoration wavelengths cost in the network;
• e. resolving wavelength conflicts that occur upon the first or second failure occurrence among restoration routes and demand working routes and among restoration routes on different path protecting preconfigured cycles that share one or more links, and preventing need for intermediate switching along restoration routes;
• and
• f. incorporating the plurality of selected path protecting preconfigured cycles, demands assigned to each of the cycles, a first failure restoration route and a second failure restoration route and restoration wavelengths assigned to each demand that requires protection from two failures, and a single restoration route and restoration wavelengths assigned to each of the demands that requires protection from a single failure for converting the optical network into the survivable optical network.

A computer readable medium having computer readable program for operating on a computer for designing a survivable optical network from an optical network comprising a plurality of nodes connected by links that provide end-to-end path restoration to a plurality of demands in the event of a single link or node failure and to a plurality of demands in the event of any two such failures using a plurality of path protecting preconfigured cycles, where in the event of the first or second failure each of the affected demands is rerouted onto a single preconfigured restoration route on a segment of a cycle using pre-specified restoration wavelengths without resorting to intermediate switching or wavelength conversions on the restoration route, comprising the steps of:

• a. generating a plurality of candidate path protecting preconfigured cycles where each of the preconfigured cycles is generated by using Dual Failure Protection Assignment Algorithm to assign demands to the cycle that require protection from any two failures and by using Single Failure Protection Assignment Algorithm to assign demands to the cycle that require protection from any single failure and where such demands restored upon first failure occurrence cannot be preempted upon the second failure occurrence, resulting in a path protecting preconfigured cycle that protects some assigned demands from two failures and some assigned demands from a single failure;
• b. generating an additional plurality of candidate path protecting preconfigured cycles where each of the preconfigured cycles is generated by using known methods to assign demands to the cycle that require protection from any single failure, resulting in a path protecting preconfigured cycle that protects all assigned demands from a single failure;
• c. selecting a set of path protecting preconfigured cycles from among all candidate path protecting preconfigured cycles so that each of the demands is protected by a single cycle by solving Set Covering Problem followed by using Elimination of Duplicate Assignments Algorithm while achieving a near-minimum total restoration wavelengths cost in the network;
• d. resolving wavelength conflicts that occur upon the first or second failure occurrence among restoration routes and demand working routes and among restoration routes on different path protecting preconfigured cycles that share one or more links, and preventing need for intermediate switching along restoration routes, by using the Wavelengths Reassignment Algorithm;
• and
• e. incorporating the plurality of selected path protecting preconfigured cycles, demands assigned to each of the cycles, a first failure restoration route and a second failure restoration route and restoration wavelengths assigned to each demand that requires protection from two failures, and a single restoration route and restoration wavelengths assigned to each of the demands that requires protection from a single failure for converting the optical network into the survivable optical network.

A computer readable medium having computer readable program for operating on a computer for designing a survivable optical network from an optical network comprising a plurality of nodes connected by links that provides end-to-end path restoration to a plurality of demands in the event of a single link or node failure and to a plurality of demands in the event of any two such failures using a plurality of path protecting preconfigured cycles, where in the event of the first or second failure each of the affected demands is rerouted onto a single preconfigured restoration route on a segment of a cycle using pre-specified restoration wavelengths without resorting to intermediate switching or wavelength conversions on the restoration route, comprising the steps of:

• a. generating a plurality of candidate path protecting preconfigured cycles where each of the preconfigured cycles protect some assigned demands from two failures and some assigned demands from a single failure;
• b. generating additional plurality of candidate path protecting preconfigured cycles where each of the preconfigured cycles is generated by using known methods to assign demands that require protection from any single failure, resulting in a path protecting preconfigured cycle that protects all assigned demands from a single failure;
• c. selecting a set of path protecting preconfigured cycles from among all candidate preconfigured cycles so that each of the demands is protected by a single cycle while achieving a near-minimum total restoration wavelengths cost in the network;
• d. resolving wavelength conflicts that occur upon the first or second failure occurrence among restoration routes and demand working routes and among restoration routes on different path protecting preconfigured cycles that share one or more links, and preventing need for intermediate switching along restoration routes;
• and
• e. incorporating the plurality of selected path protecting preconfigured cycles, demands assigned to each of the cycles, a first failure restoration route and a second failure restoration route and restoration wavelengths assigned to each demand that requires protection from two failures, and a single restoration route and restoration wavelengths assigned to each of the demands that requires protection from a single failure for converting the optical network into the survivable optical network.

A computer system for designing a survivable optical network from an optical network comprising a plurality of nodes connected by links that provide end-to-end path restoration to a plurality of demands in the event of a single link or node failure and to a plurality of demands in the event of any two such failures using a plurality of path protecting preconfigured cycles, where in the event of the first or second failure each of the affected demands is rerouted onto a single preconfigured restoration route on a segment of a cycle using pre-specified restoration wavelengths without resorting to intermediate switching or wavelength conversions on the restoration route, comprising:

• a. means for generating a plurality of candidate path protecting preconfigured cycles where each of the preconfigured cycles is generated by using Dual Failure Protection Assignment Algorithm to assign demands to the cycle that require protection from any two failures and by using Single Failure Protection Assignment Algorithm to assign demands to the cycle that require protection from any single failure and where such demands restored upon first failure occurrence cannot be preempted upon the second failure occurrence, resulting in a path protecting preconfigured cycle that protects some assigned demands from two failures and some assigned demands from a single failure;
• b. means for generating an additional plurality of candidate path protecting preconfigured cycles where each of the preconfigured cycles is generated by using known methods to assign demands to the cycle that require protection from any single failure, resulting in a path protecting preconfigured cycle that protects all assigned demands from a single failure;
• c. means for selecting a set of path protecting preconfigured cycles from among all candidate path protecting preconfigured cycles so that each of the demands is protected by a single cycle by solving Set Covering Problem followed by using Elimination of Duplicate Assignments Algorithm while achieving a near-minimum total restoration wavelengths cost in the network;
• d. means for resolving wavelength conflicts that occur upon the first or second failure occurrence among restoration routes and demand working routes and among restoration routes on different path protecting preconfigured cycles that share one or more links, and preventing need for intermediate switching along restoration routes, by using Wavelengths Reassignment Algorithm;
• and
• e. means for incorporating the plurality of selected path protecting preconfigured cycles, demands assigned to each of the cycles, a first failure restoration route and a second failure restoration route and restoration wavelengths assigned to each demand that requires protection from two failures, and a single restoration route and restoration wavelengths assigned to each of the demands that requires protection from a single failure for converting the optical network into the survivable optical network.

A computer system for designing a survivable optical network that provides end-to-end path restoration to a plurality of demands in the event of a single link or node failure and to a plurality of demands in the event of any two such failures using a plurality of path protecting preconfigured cycles, where in the event of the first or second failure each of the affected demands is rerouted onto a single preconfigured restoration route on a segment of a cycle using pre-specified restoration wavelengths without resorting to intermediate switching or wavelength conversions on the restoration route, comprising:

• a. an optical network comprising nodes connected by links;
• b. a means for generating a plurality of candidate path protecting preconfigured cycles where each of the preconfigured cycles protect some assigned demands from two failures and some assigned demands from a single failure;
• c. means for generating additional plurality of candidate path protecting preconfigured cycles where each of the preconfigured cycles is generated by using known methods to assign demands that require protection from any single failure, resulting in a path protecting preconfigured cycle that protects all assigned demands from a single failure;
• d. means for selecting a set of path protecting preconfigured cycles from among all candidate preconfigured cycles so that each of the demands is protected by a single cycle while achieving a near-minimum total restoration wavelengths cost in the network;
• e. means for resolving wavelength conflicts that occur upon the first or second failure occurrence among restoration routes and demand working routes and among restoration routes on different path protecting preconfigured cycles that share one or more links, and preventing need for intermediate switching along restoration routes;
• and
• f. means for incorporating the plurality of selected path protecting preconfigured cycles, demands assigned to each of the cycles, a first failure restoration route and a second failure restoration route and restoration wavelengths assigned to each demand that requires protection from two failures, and a single restoration route and restoration wavelengths assigned to each of the demands that requires protection from a single failure for converting the optical network into the survivable optical network.