# US 7,609,964 B2 · Power level management in optical networks

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- Number: US 7,609,964 B2
- Document ID: US7609964B2
- Status: Granted
- Kind: B2
- Application number: 11/799,021
- Filed: 2007-04-30
- Published: 2007-08-30
- Granted: 2009-10-27
- Earliest claimed: 2002-04-12
- Assignees: Fujitsu Limited
- Inventors: Kumar Vijay Peddanarappagari; Jamil Omar-Hatem El-Reedy; Emir Catovic
- Web page: https://patentgrep.com/patent/US7609964B2

## CPC

- H04B 10/077: using a supervisory or additional signal
- H04B 10/07955: {Monitoring or measuring power}
- H04J 14/02216: {by gain equalization}
- H04J 14/02219: {Distributed control}
- H04J 14/0227: {Operation, administration, maintenance or provisioning [OAMP] of WDM networks, e.g. media access, routing or wavelength allocation}
- H04J 14/0246: {using one wavelength per ONU}
- H04J 14/0201: {Add-and-drop multiplexing}
- H04J 14/0284: {WDM mesh architectures}
- H04J 14/0293: {Optical channel protection}
- 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)

## Abstract

In an optical communication network, optical communication nodes exchange information detailing power level variations to support management and administration of optical communications. This exchange of information permits nodes to determine aggregate power level variations over light paths to support operations such as selection from available light paths and configuration of optical communication characteristics.

## Claims

### Claim 1

A method for power level management of optical communications, the method comprising:
receiving a request to establish a communication channel with a remote optical node;
determining a plurality of light paths to the remote optical node;
for each of the light paths:
determining a next node for the light path to the remote optical node;
determining add power level variation for the light path;
generating a path setup message identifying the light path and the add power variation; and
communicating the path setup message to the next node;
determining an aggregate power level variation for each of the light paths;
selecting one of the light paths based on the determined aggregate power level variations; and
configuring variable attenuation for the selected light path to accommodate for the aggregate power level variation for the selected light path.

### Claim 2 (depends on 1)

The method of claim 1, further comprising configuring optical communication equipment based on the aggregate power level variation for the selected light path.

### Claim 3 (depends on 1)

The method of claim 1, wherein selecting comprises choosing one of the light paths with the aggregate power level variation closest to a target value.

### Claim 4 (depends on 1)

The method of claim 1, further comprising, for each of the light paths, reserving a resource to the next node for the light path.

### Claim 5 (depends on 4)

The method of claim 4, further comprising:
receiving a path setup failure message for an identified one of the light paths; and
in response to the path setup failure message, releasing the resource reserved for the identified light path.

### Claim 6 (depends on 4)

The method of claim 4, further comprising:
releasing the reserved resources for all of the light paths other than the selected light path.

### Claim 7 (depends on 1)

The method of claim 1, further comprising maintaining add data indicating an add power level variation for each of a plurality of channels.

### Claim 8

An optical communication node comprising:
a cross-connect fabric operable to receive optical communications from an input fiber and an add fiber and to switch received optical communications for transmission on a selected one of an output fiber and a drop fiber; and
a controller operable to receive a request to establish a communication channel with a remote optical node and to determine a plurality of light paths to the remote optical node, the controller further operable, for each of the light paths, to determine a next node for the light path to the remote optical node, to determine add power level variation for the light path, to generate a path setup message identifying the light path and the add power variation, to communicate the path setup message to the next node, to determine an aggregate power level variation for each of the light paths, to select one of the light paths based on the determined aggregate power level variations, and to configure variable attenuation for the selected light path to accommodate for the aggregate power level variation for the selected light path.

### Claim 9 (depends on 8)

The node of claim 8, further comprising:
a first optical amplifier coupled to the cross-connect fabric and operable to receive optical communications from the input fiber; and
a second optical amplifier coupled to the cross-connect fabric and operable to transmit optical communications on the output fiber.

### Claim 10 (depends on 9)

The node of claim 9, further comprising a memory maintaining add data indicating an add power level variation for each of a plurality of channels.

### Claim 11 (depends on 10)

The node of claim 10, wherein the add power level variation for a channel indicates variation in power between an output of a device coupled to the add fiber and the second optical amplifier at a wavelength of the channel.

### Claim 12 (depends on 8)

The node of claim 8, wherein the controller is further operable to select by choosing one of the light paths with the aggregate power level variation closest to a target value.

### Claim 13 (depends on 8)

The node of claim 8, wherein the controller is further operable, for each of the light paths, to reserve a resource to the next node for the light path.

### Claim 14 (depends on 13)

The node of claim 13, wherein the controller is further operable to:
receive a path setup failure message for an identified one of the light paths; and
in response to the path setup failure message, release the resource reserved for the identified light path.

### Claim 15 (depends on 13)

The node of claim 13, wherein the controller is further operable to:
release the reserved resources for all of the light paths other than the selected light path.

### Claim 16

A computer-readable medium encoded with logic for power level management of optical communications, the logic operable when executed by a computer to:
receive a request to establish a communication channel with a remote optical node;
determine a plurality of light paths to the remote optical node;
for each of the light paths:
determine a next node for the light path to the remote optical node;
determine add power level variation for the light path;
generate a path setup message identifying the light path and the add power variation; and
communicate the path setup message to the next node;
determine an aggregate power level variation for each of the light paths;
select one of the light paths based on the determined aggregate power level variations; and
configure variable attenuation for the selected light path to accommodate for the aggregate power level variation for the selected light path.

### Claim 17 (depends on 16)

The computer-readable medium of claim 16, wherein the logic is further operable to configure optical communication equipment based on the aggregate power level variation for the selected light path.

### Claim 18 (depends on 16)

The computer-readable medium of claim 16, wherein the logic is further operable to select by choosing one of the light paths with the aggregate power level variation closest to a target value.

### Claim 19 (depends on 16)

The computer-readable medium of claim 16, wherein the logic is further operable, for each of the light paths, to reserve a resource to the next node for the light path.

### Claim 20 (depends on 19)

The computer-readable medium of claim 19, wherein the logic is further operable to:
receive a path setup failure message for an identified one of the light paths; and
in response to the path setup failure message, release the resource reserved for the identified light path.

### Claim 21 (depends on 19)

The computer-readable medium of claim 19, wherein the logic is further operable to:
release the reserved resources for all of the light paths other than the selected light path.

### Claim 22 (depends on 16)

The computer-readable medium of claim 16, wherein the logic is further operable to maintain add data indicating an add power level variation for each of a plurality of channels.

### Claim 23

An optical communication node comprising:
means for receiving a request to establish a communication channel with a remote optical node;
means for determining a plurality of light paths to the remote optical node; and
means for, for each of the light paths:
determining a next node for the light path to the remote optical node;
determining add power level variation for the light path;
generating a path setup message identifying the light path and the add power variation; and
communicating the path setup message to the next node;
means for determining an aggregate power level variation for each of the light paths;
means for selecting one of the light paths based on the determined aggregate power level variations; and
means for configuring variable attenuation for the selected light path to accommodate for the aggregate power level variation for the selected light path.

### Claim 24

A system for power level management of optical communications comprising:
a source node operable:
to receive a request to establish a communication channel with a destination node;
to determine a plurality of light paths to the destination node; and
for each of the light paths: to determine a first node on the light path to the destination node, to determine an add power level variation for the light path, to generate a path setup message identifying the light path and a power level variation value equal to the add power level variation, and to communicate the path setup message to the first node;
a plurality of intermediate nodes, each intermediate node operable to receive at least one of the path setup messages and, for each received path setup message:
to determine whether a channel to a next node in the light path identified in the received path setup message is available, the next node comprising either the destination node or another one of the intermediate nodes; and
if the channel is available: to determine a through power level variation for the light path, to add the through power level variation to the power level variation value in the received path setup message, and to communicate the received path setup message to the next node; and
the destination node operable:
to receive one or more of the path setup messages; and
for each path setup message: to determine a drop power level variation for the light path identified in the path setup message, to add the drop power level variation to the power level variation value in the path setup message to obtain an aggregate power level variation for the light path, to generate a setup reply message indicating the light path and the aggregate power level variation for the light path, and to communicate the setup reply message to the source node.