# US 12,001,071 B2 · Detection of single points of failure in multiple shared risk link groups

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- Number: US 12,001,071 B2
- Document ID: US12001071B2
- Status: Granted
- Kind: B2
- Application number: 17/458,446
- Filed: 2021-08-26
- Published: 2023-03-02
- Granted: 2024-06-04
- Earliest claimed: 2021-08-26
- Assignees: Microsoft Technology Licensing, LLC
- Applicants: Microsoft Technology Licensing, LLC
- Inventors: Kyle Louis Edwards
- Web page: https://patentgrep.com/patent/US12001071B2

## CPC

- G02B 6/4427: {Pressure resistant cables, e.g. undersea cables}
- G02B 6/381: {of the ferrule type, e.g. fibre ends embedded in ferrules, connecting a pair of fibres}
- H04B 10/03: Arrangements for fault recovery
- H04B 10/27: Arrangements for networking
- H04J 14/0267: {Optical signaling or routing}
- H04L 45/28: using route fault recovery
- G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- H04B: TRANSMISSION
- H04J: MULTIPLEX COMMUNICATION (transmission in general H04B; peculiar to transmission of digital information H04L5/00; systems for the simultaneous or sequential transmission of more than one television signal H04N7/08; in exchanges H04Q11/00; stereophonic systems H04S)
- H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M)

## Abstract

Rectangular equidistant projection is applied to coordinates for path fragments of a plurality of fiber optic routes. A bounding box is generated for each path fragment. For each cell of a grid of cells where its bounding box overlaps with a bounding box created by the cell, each path fragment is placed into the cell of the global grid. For any cell with more than one path fragment, each path fragment inside the cell is compared to every other path fragment in that cell. For any path fragment with overlapping bounding boxes, the length of the overlap is saved. A table of cumulative overlap distances between path fragments is generated to identify overlapping segments and cumulative lengths of the overlap distances.

## Claims

### Claim 1

A system configured to analyze a plurality of fiber optic routes, the system comprising:
one or more processors; and
a memory in communication with the one or more processors, the memory having computer-readable instructions stored thereupon that, when executed by the one or more processors, cause the system to perform operations comprising:
determining a geographic tolerance for a shared risk link group (SRLG) of the fiber optic routes;
determining a maximum number of coordinates for path fragments of the fiber optic routes;
applying rectangular equidistant projection to the maximum number of coordinates for the path fragments;
using the rectangular equidistant projection, generating a bounding box for each path fragment, wherein the bounding box is expanded by the geographic tolerance;
generating a global grid of cells;
associating each path fragment with any cell of the global grid where each path fragment's bounding box overlaps with the cell;
for any cell associated with more than one path fragment:
comparing each path fragment inside the cell to every other path fragment associated with that cell to identify path fragments with overlapping bounding boxes; and
for path fragments that have overlapping bounding boxes, saving a length of the overlap, wherein the length is a distance for which a projected distance on a common reference plane is within the geographic tolerance; and
based on cumulative overlap distances between path fragments, identifying overlapping fiber optic routes and cumulative lengths of the overlap.

### Claim 2 (depends on 1)

The system of claim 1, wherein the geographic tolerance is 10 meters.

### Claim 3 (depends on 1)

The system of claim 1, wherein the maximum number of coordinates is 50 coordinates.

### Claim 4 (depends on 1)

The system of claim 1, further comprising computer-readable instructions stored thereupon that, when executed by the one or more processors, cause the system to perform operations comprising transforming the coordinates so that antemeridian crossings do not cause discontinuities.

### Claim 5 (depends on 1)

The system of claim 1, wherein the rectangular equidistant projection comprises (x=lon*cos(lat), y=lat).

### Claim 6 (depends on 1)

The system of claim 1, wherein the global grid of cells is 5 degrees by 5 degrees from −180.0,90.0 to 180.0,−90.0 degrees.

### Claim 7 (depends on 1)

The system of claim 1, wherein overlap lengths are determined by transforming coordinates of path a so that it becomes the origin, and performing polar rotation where theta=atan 2(y,x).

### Claim 8

A method for identifying a shared risk link group (SRLG) among a plurality of fiber optic routes, comprising:
applying rectangular equidistant projection to coordinates for path fragments of the fiber optic routes;
based on the rectangular equidistant projection, generating a bounding box for each path fragment, wherein the bounding box is expanded by a geographic tolerance;
for each cell of a grid of cells that overlaps with a bounding box created of the cell, associating each path fragment with the cell of a global grid;
for any cell associated with more than one path fragment:
comparing each path fragment associated with the cell to every other path fragment associated with that cell; and
for any path fragment with overlapping bounding boxes, saving a length of the overlap;
using cumulative overlap distances between path fragments to identify overlapping segments and cumulative lengths of the overlap distances; and
based on the overlapping segments and cumulative lengths, identifying an SRLG.

### Claim 9 (depends on 8)

The method of claim 8, further comprising transforming the coordinates so that antemeridian crossings do not cause discontinuities.

### Claim 10 (depends on 8)

The method of claim 8, wherein the rectangular equidistant projection comprises (x=lon*cos(lat), y=lat).

### Claim 11 (depends on 8)

The method of claim 8, wherein the global grid is 5 degrees by 5 degrees from −180.0,90.0 to 180.0, −90.0 degrees.

### Claim 12 (depends on 8)

The method of claim 8, wherein overlap lengths are determined by transforming coordinates of path a so that it becomes the origin, and performing polar rotation where theta=atan 2(y,x).

### Claim 13 (depends on 8)

The method of claim 8, wherein the geographic tolerance is 10 meters.

### Claim 14 (depends on 8)

The method of claim 8, wherein the maximum number of coordinates is 50 coordinates.

### Claim 15

A computer-readable storage medium having computer-executable instructions stored thereupon which, when executed by one or more processors of a computing device, cause the computing device to:
apply rectangular equidistant projection to coordinates for path fragments of a plurality of fiber optic routes;
based on the rectangular equidistant projection, generate a bounding box for each path fragment, wherein the bounding box is expanded by a geographic tolerance;
for each cell of a grid of cells where its bounding box overlaps with a bounding box created by the cell, associate each path fragment with the cell of a global grid;
for any cell with more than one path fragment, compare each path fragment inside the cell to every other path fragment in that cell;
for any path fragment with overlapping bounding boxes, store a length of the overlap; and
based on cumulative overlap distances between path fragments, identify overlapping segments and cumulative lengths of the overlap distances; and
based on the overlapping segments and cumulative lengths, identifying a shared risk link group.

### Claim 16 (depends on 15)

The computer-readable storage medium of claim 15, further comprising computer-readable instructions that, when executed by the one or more processors, cause the computing device to transform the coordinates so that antemeridian crossings do not cause discontinuities.

### Claim 17 (depends on 15)

The computer-readable storage medium of claim 15, wherein the rectangular equidistant projection comprises (x=lon*cos(lat), y=lat).

### Claim 18 (depends on 17)

The computer-readable storage medium of claim 17, wherein the global grid is 5 degrees by 5 degrees from −180.0,90.0 to 180.0, −90.0 degrees.

### Claim 19 (depends on 17)

The computer-readable storage medium of claim 17, wherein the geographic tolerance and the maximum number of coordinates are predetermined.

### Claim 20 (depends on 15)

The computer-readable storage medium of claim 15, wherein overlap lengths are determined by transforming coordinates of path a so that it becomes the origin, and performing polar rotation where theta=atan 2(y,x).