US5850505A
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US
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Method for preconfiguring a network to withstand anticipated failures
Assignee: Telecommunications Res Labs
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Filing: 1995-11-01
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Granted: 1998-12-15
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Expires: 2015-11-01
Abstract
Abstract A method for restoring traffic in a network. The network includes plural distinct nodes interconnected by plural distinct spans, each span having working links and spare links. Each node has a digital cross-connect switch for making and breaking connections between adjacent spans forming span pairs at a node. Step 1: For each of at least two possible span failures, (a) find the number of restoration routes available in case of the occurrence of each span failure, (b) determine the resources used by each restoration route, and (c) determine the amount of flow to be restored for each span failure. Step 2: find, in a computer, the amount of flow f p to be restored along each restoration route that minimizes total unrestored flow for all possible span failures identified in step 1. Step 3: form connections at each digital cross-connect switch in the network along each restoration route before occurrence of one of the possible span failures identified in step 1 to permit the amount of flow f p determined in step 2 to be carried by each respective restoration route upon the occurrence of one of the possible span failures identified in step 1.
Inventors
- 👤 Wayne D. Grover
- 👤 Michael H. MacGregor
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 10:45
CPC Classifications
H; H04; H04J; H04J3/00; H04J3/02; H04J3/14; H04L; H04L41/00; H04L41/06; H04L41/0654; H04L41/0663
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
210 words
A method for restoring traffic in a network in which the network includes plural distinct nodes interconnected by plural distinct spans, each span having working links and spare links, and having a span capacity, each node having a digital cross-connect switch for making and breaking connections between links in adjacent spans forming span paths through a node, the method comprising the steps of: (1) for each of at least two possible span failures, (a) finding a number of restoration routes that are available in case of the occurrence of each span failure, (b) determining the resources used by each restoration route, and (c) determining the amount of flow to be restored for each span failure; (2) finding, in a computer, the amount of flow f p to be restored along each restoration route that minimizes total unrestored flow for all possible span failures identified in step 1; and (3) forming connections at each digital crossconnect switch in the network along each restoration route before occurrence of one of the possible span failures identified in step 1 to permit the amount of flow f p determined in step 2 to be carried by each respective restoration route upon the occurrence of one of the possible span failures identified in step 1.
Claim 2
Independent Claim
210 words
A method for restoring traffic in a network in which the network includes plural distinct nodes interconnected by plural distinct spans, each span having working links and spare links, and having a span capacity, each node having a digital cross-connect switch for making and breaking connections between links in adjacent spans forming span paths through a node, the method comprising the steps of: (1) for each of at least two possible span failures, (a) finding a number of restoration routes that are available in case of the occurrence of each span failure, (b) determining the resources used by each restoration route, and (c) determining the amount of flow to be restored for each span failure; (2) finding, in a computer, the amount of flow f p to be restored along each restoration route that minimizes total unrestored flow for all possible span failures identified in step 1; and (3) forming connections at each digital crossconnect switch in the network along each restoration route before occurrence of one of the possible span failures identified in step 1 to permit the amount of flow f p determined in step 2 to be carried by each respective restoration route upon the occurrence of one of the possible span failures identified in step 1.
Claim 3
Dependent Claim
67 words
The method of claim 1 further including: finding in a computer an assignment of connections between links in adjacent spans in the network that minimizes total unrestored flow for all possible span failures identified in step 1; and forming the connections at each digital cross-connect switch in the network by instructing each digital cross-connect switch in the network to make connections according to the assignment of connections.
Claim 4
Dependent Claim
51 words
The method of claim 1 in which finding, in a computer, the amount of flow f p to be restored along each restoration route includes: forming a transformed network in which each span pair at a node is an edge in the transformed network and edges between adjacent nodes are cross-connected.
Claim 5
Dependent Claim
77 words
The method of claim 1 in which finding, in a computer, the amount of flow f p to be restored along each restoration route includes: generating a first set of constraints relating the number of connections preconfigured for restoration between each two adjacent spans of the original network to the capacities of the two adjacent spans; and minimizing total unrestored flow for all possible span failures identified in step 1 subject to the first set of constraints.
Claim 6
Dependent Claim
79 words
The method of claim 1 in which finding, in a computer, the amount of flow f p to be restored along each restoration route includes: generating a second set of constraints relating the amount of flow to be restored between each two adjacent spans of the original network to the number of spare links between the adjacent spans; and minimizing total unrestored flow for all possible span failures identified in step 1 subject to the second set of constraints.
Claim 7
Dependent Claim
77 words
The method of claim 1 in which finding, in a computer, the amount of flow f p to be restored along each restoration route includes: generating a third set of constraints relating the amount of flow to be restored between three consecutive spans of the original network to the capacity of cross-connections between the consecutive spans; and minimizing total unrestored flow for all possible span failures identified in step 1 subject to the third set of constraints.
Claim 8
Dependent Claim
76 words
The method of claim 1 in which finding, in a computer, the amount of flow f p to be restored along each restoration route includes: generating a fourth set of constraints relating the amount of flow used to restore a particular span failure to the number of working links on the particular span before failure; and minimizing total unrestored flow for all possible span failures identified in step 1 subject to the fourth set of constraints.
Claim 9
Dependent Claim
83 words
The method of claim 1 in which finding, in a computer, the amount of flow f p to be restored along each restoration route includes: generating a fifth set of constraints relating the amount of flow on a particular span that cannot be restored upon the failure of that span to the number of working links on the particular span before failure; and minimizing total unrestored flow for all possible span failures identified in step 1 subject to the fifth set of constraints.
Claim 10
Dependent Claim
74 words
The method of claim 1 in which finding, in a computer, the amount of flow f p to be restored along each restoration route includes: generating a sixth set of constraints relating the number of working links of a particular span before failure of that span to the restoration capacity of that span; and minimizing total unrestored flow for all possible span failures identified in step 1 subject to the sixth set of constraints.
Claim 11
Dependent Claim
24 words
The method of claim 1 further including, upon occurrence of a span failure, restoring capacity in the network according to a real-time restoration process.
Claim 12
Dependent Claim
67 words
The method of claim 1 in which forming the connections at each digital cross-connect switch in the network is carried out, for each restoration route, by: identifying a starting node in the restoration route; and instructing the digital cross-connect switch at that node, and at each subsequent node in the network along the restoration route, to make connections determined by the restoration flow for that restoration route.
Claim 13
Independent Claim
205 words
A method for restoring traffic in a network in which the network includes plural distinct nodes interconnected by plural distinct spans, each span having working links and spare links, and having a span capacity, each node having a digital cross-connect switch for making and breaking connections between adjacent spans forming span paths through a node, the method comprising the steps of: (1) for each of at least two possible span failures, (a) finding the number of restoration routes available in case of the occurrence of each span failure, (b) determining the resources used by each restoration route, and (c) determining the amount of flow to be restored for each span failure; (2) finding, in a computer, the amount of flow f p to be restored along each restoration route that minimizes spare capacity for all possible span failures identified in step 1; and (3) forming connections at each digital cross-connect switch in the network along each restoration route before occurrence of one of the possible span failures identified in step 1 to permit the amount of flow f p determined in step 2 to be carried by each respective restoration route upon the occurrence of one of the possible span failures identified in step 1.
Claim 14
Independent Claim
205 words
A method for restoring traffic in a network in which the network includes plural distinct nodes interconnected by plural distinct spans, each span having working links and spare links, and having a span capacity, each node having a digital cross-connect switch for making and breaking connections between adjacent spans forming span paths through a node, the method comprising the steps of: (1) for each of at least two possible span failures, (a) finding the number of restoration routes available in case of the occurrence of each span failure, (b) determining the resources used by each restoration route, and (c) determining the amount of flow to be restored for each span failure; (2) finding, in a computer, the amount of flow f p to be restored along each restoration route that minimizes spare capacity for all possible span failures identified in step 1; and (3) forming connections at each digital cross-connect switch in the network along each restoration route before occurrence of one of the possible span failures identified in step 1 to permit the amount of flow f p determined in step 2 to be carried by each respective restoration route upon the occurrence of one of the possible span failures identified in step 1.
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| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
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| 3.5 Years (Year 4) | 2001-12-14 | 2002-06-15 | 2002-12-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2005-12-14 | 2006-06-15 | 2006-12-15 | $3760.00 | Window Closed / Lapsed |
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