WO2002075972A1

WO2002075972A1 - Method and apparatus for monitoring an optical network

Info

Publication number: WO2002075972A1
Application number: PCT/US2002/006950
Authority: WO
Inventors: Nicolas William Spiridon
Original assignee: Worldcom, Inc.
Priority date: 2001-03-16
Filing date: 2002-03-07
Publication date: 2002-09-26

Abstract

An approach for monitoring a plurality of optical signals is disclosed. An optical monitoring unit (200) receives a plurality of optical signals; the optical monitoring unit includes a plurality of optical splitters (203) that are configured to receive the plurality of optical signals. Each of the plurality of optical signals has a different wavelength. The optical monitoring unit also includes a plurality of photo diodes (205) that are coupled correspondingly to the plurality of optical splitters and are configured to receive a portion of each of the optical signals. The portions of the optical signals are converted to electrical signals. A processing unit (211) is configured to analyze the electrical signals for an abnormal condition.

Description

TITLE OF THE INVENTION

METHOD AND APPARATUS FOR

MONITORING AN OPTICAL NETWORK

BACKGROUND OF THE INVENTION

Field of the Invention:

[01] The present invention relates to network management and restoration, and is more

particularly related to monitoring of an optical network.

Discussion of the Background

[02] Given the bandwidth demands of modern networks, service providers have turned to the

nearly limitless transport capabilities of optical networks. Because of the convergence of the

various telecommunication services, the mix of traffic that are carried over an optical network

include data, voice, and video signals, which may carry rich multimedia information to a

multitude of users. Service providers have been particularly challenged by the ever growing

Internet traffic, deploying optical networks with line rates of OC-3c (Optical Carrier) up to OC-

192; advances in optical networking technologies have promises of even greater transmission

rates (i.e., terabits per second). The subscribers (i.e., customers) of these service providers have

come to rely heavily on the network infι-astructure to transact business or transport other mission

critical data. These subscribers can ill afford network downtime, which has a direct negative

impact on profitability and satisfaction of service level agreements. Therefore, effective monitoring of these optical networks play a crucial role in a service provider's ability to stay

competitive in an industiy in which the subscribers are sophisticated and demanding. Further,

the integration of monitoring capabilities with that service provisioning can enhance the

competitiveness of the service provider.

[03] Because optical cables cany a significantly higher amount of information relative to

conventional electrical cables, a fault within the optical network accordingly affects a larger

subscriber base. For example, a fiber cable cut of an OC-192 link, which has the capacity to

transport over 128,000 voice calls, would undoubtedly be viewed with great disdain by the

affected customers. Events, other than a fiber cable cut, can disrupt service; for example, optical

networking components that are employed along the optical link may fail. Consequently,

network management and restoration of optical communication systems have grown ever more

important.

[04] With conventional optical networks, there is a lack of optical monitoring capability at the

optical cross-connect at the demarcation point between service provider and customer. Also, the

conventional approach network monitoring of optical communication systems does not provide

the capability to remotely identify the different wavelengths and monitoring capability of the

incoming optical signal to the optical switches. Furthermore, the conventional approach lacks

the capability to monitor various optical input interfaces to the passive optical units (POUs).

[05] Based on the foregoing, there is a clear need for improved approaches for providing

network monitoring and restoration of optical communication systems.

[06] There is also a need to minimize network downtime.

[07] There is a further need to provide an effective mechanism for monitoring passive optical

units. [08] Based on the need' to enhance the network availability, an approach for implementing a

network protection mechanism in a submarine cable network is highly desirable.

SUMMARY OF THE INVENTION

[09] The present invention addresses the above stated needs by providing an optical monitoring

unit (OMU) that is capable of monitoring passive optical units (POUs). The OMU contains optical

splitters, which transmit portions of the energies of the optical signals to photodiodes. The

photodiodes, in turn, convert the received optical signals into their electrical equivalents. These

electrical signals are transmitted to a processing unit, which analyzes the electrical signals to

deteπnine whether an abnormal condition exists. Upon detection of an abnormal condition,

network restoration measurements can be taken. This ability to monitor the optical network

facilitates the provisioning of services for the customers.

[10] According to one aspect of the invention, an apparatus for monitoring a plurality of

optical signals is disclosed. A plurality of optical splitters are configured to receive the plurality

of optical signals. Each of the plurality of optical signals has a different wavelength. ^' A plurality

of photo diodes are coupled correspondingly to the plurality of optical splitters and are

configured to receive a portion of each of the optical signals. The portions of the optical signals

are converted to electrical signals, wherein the electrical signals are transmitted to a processing

unit that is configured to analyze the electrical signals for an abnormal condition. Under this

approach, the origin of a fault can be easily identified.

[11] According to one aspect of the invention, a method is provided for monitoring a plurality

of optical signals. The method includes receiving the plurality of optical signals having a

different wavelength. The method also includes splitting the plurality of optical signals to output portions of the plurality of optical signals, and converting the portions of the plurality of optical

signals into electrical signals. The method further includes transmitting the electrical signals to a

processing unit, and analyzing the electrical signals for an abnormal condition. Under this

approach, local maintenance personnel can avoid causing an accidental outage.

[12] According to another aspect of the invention, a system is provided for monitoring a

plurality of optical signals. An optical monitoring unit is configured to receive the plurality of

optical signals. The optical monitoring unit comprises a plurality of optical splitters that are

configured to receive the plurality of optical signals, wherein each of the plurality of optical

signals has a different wavelength. The optical monitoring unit also includes a plurality of photo

diodes that are coupled correspondingly to the plurality of optical splitters and are configured to

receive a portion of each of the optical signals. The portions of the optical signals are converted

to electrical signals. A processing unit is configured to analyze the electrical signals for an

abnormal condition. The above arrangement advantageously provides an effective mechanism to

detect network problems and to appropriately alert the network components.

[13] In another aspect of the invention, a computer-readable medium carrying one or more

sequences of one or more instructions for monitoring a plurality of optical signals is provided.

The one or more sequences of one or more instructions include instructions which, when

executed by one or more processors, cause the one or more processors to perform the step of

receiving electrical signals from an optical monitoring unit having a plurality of input ports. The

received electrical signals are converted from a plurality of optical signals having a different

wavelength. Other steps include analyzing the electrical signals for an abnormal condition, and

selectively generating an alarm signal in response to the analyzing step. This approach

advantageously permits monitoring of passive optical units. [14] In yet another aspect of the invention, an apparatus is provided for monitoring a plurality

of optical signals. The apparatus includes means for receiving the plurality of optical signals

having a different wavelength, means for splitting the plurality of optical signals to output

portions of the plurality of optical signals, and means for converting the portions of the plurality

of optical signals into electrical signals. Additionally, the apparatus includes means for

transmitting the electrical signals to a processing unit, and means for analyzing the electrical

signals for an abnormal condition. Under this approach, network faults can be readily isolated.

BRIEF DESCRIPTION OF THE DRAWINGS

[15] A more complete appreciation of the invention and many of the attendant advantages

thereof will be readily obtained as the same becomes better understood by reference to the

following detailed description when considered in connection with the accompanying drawings,

wherein:

[16] Figure 1 is a diagram of a system for monitoring an optical network, in accordance Avith

an embodiment of the present invention;

[17] Figure 2 is a diagram of an optical monitoring unit (OMU), according to an embodiment

of the present invention;

[18] Figure 3 is a flow chart of a process of monitoring the optical network of Figure 2;

[19] Figure 4 is a flow chart of a provisioning process, in accordance with an embodiment of

the present invention;

[20] Figures 5A-5C are exemplary screens of the graphical user interface (GUI) to provision

services according to the process of Figure 4; and [21] Figure 6 is a diagi'am of a computer system that can perfoπn the operations according to

an embodiment of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[22] In the following description, for the purpose of explanation, specific details are set forth

in order to provide a thorough understanding of the invention. However, it will be apparent that

the invention may be practiced without these specific details. In some instances, well-known

structures and devices are depicted in block diagram form in order to avoid unnecessarily

obscuring the present invention.

[23] Figure 1 shows a diagi'am of a system employing an optical monitoring unit (OMU),

according to an embodiment of the present invention. An optical communication system 100

utilizes a switch 101 that has connectivity to an optical cross-connect (OXC) 103. Switch 101

may be an optical switch that processes voice and data traffic from multiple nodes (not shown)

for transmission to a terminating switch (not shown) of network 105. Optical cross-connect 103

may switch high-speed optical signals (e.g., OC-3, OC-48, OC-192, etc.) their entirety without

multiplexing. Optical cross-connect 103 operates at the optical layer and does not require

conversion from electrical-to-optical and optical-to-electrical. In an exemplary embodiment,

system 100 supports any number of physical layer and higher layer protocols; for example,

SONET (Synchronous Optical NETwork), SDH (Synchronous Digital Hierarchy), ATM

(Asynchronous Transfer Mode), and TCP/IP (Transmission Control Protocol/Internet Protocol).. Optical cross-connect 103 may operate using a number of different optical carriers of different

wavelengths, λ, to λ_n, and interfaces with an optical monitoring unit 107.

[24] OMU 107 also may receive optical signals from various passive optical units (PO Is)

109, such a optical filters. The various optical input ports of OMU 107 that interface with the

POUs 109 can be monitored. OMU 107 may be deployed as an integral part of the POUs 109 so

that the monitoring capability for the POUs 109 is available. That is, POUs 109 may be an

integral part of any high bandwidth transport equipment.

[25] OMU 107 converts the received optical signals from optical cross-connect 103 and POUs

109 and transmits their electrical equivalent to a processing unit 111 over network 105. Network

105 may contain network elements (e.g., switches, internetworking devices, etc.) that operate at

the electrical and/or optical layers. Processing unit 11 1 analyzes the received electrical signals to

determine whether a fault exists within the POUs 109 or equipment that terminates at OXC 103,

such as switch 101. For the purposes of explanation, a network card in switch 101 is assumed to

have failed, thereby triggering a fault condition within processing unit 111. Upon detection of

this fault, processing unit 111, may generate an appropriate alarm signal to alert the switch 101.

Alternatively, the processing unit 111 may transmit the alarm to a network management system

(not shown) that is responsible for the operation and maintenance of switch 101.

[26] As evident from the above discussion, OMU 107 may be used to monitor optical inputs

of the various wavelengths (λ, to λ_n) at optical cross-connect 103, which may seive as the

demarcation point bet-ween a customer and a service provider. This arrangement provides a

simplified mechanism to identify the origin of a network problem. OMU 107 provides multiple

input ports, in which each of the input ports is mapped to a different wavelength. Through this identification mechanism, the chance that a maintenance personnel, for example, causes an

accidental outage by shutting down the incoirect link is minimized.

[27] Figure 2 shows a diagram of an OMU, according to an embodiment of the present

invention. OMU 200 has a number of input ports 201, which in this example, totals m and

corresponds to the wavelengths, λ, to λ_n, of the optical signals. As seen in the figure, OMU 200

employs optical splitters 203 and photo diodes 205. The number of splitters 203 and photo

diodes 205 correspond to the number of input ports 201; accordingly, m number of splitters 203

and photo diodes 205 are shown. Each of the splitters 203a, 203b, 203c, 203d, and 203e permits

a small percentage of the power of the incoming light wave to be fed into the respective photo

diodes 205a, 205b, 205c, 205d, and 205e, which convert the light into equivalent electrical

signals. These electrical signals, according to one embodiment of the present invention, are fed

into a local maintenance shelf 207.

[28] The maintenance shelf 207 may then supply these electrical signals over a network 209 to

a Remote Monitoring Processing Unit (RMPU) 211. RMPU 211 may detect the interruption of

light, which could be caused by any number of perturbations, by detecting the ON and OFF

states of the electrical signal. The presence of an electrical signal may represent the ON state,

thereby indirectly indicating the presence of the corresponding light wave. In rum, absence of an

electrical signal (consequently the associated light wave) may signify the OFF state. Thus, the

failure to receive an optical signal at the OMU 200 may cause the corresponding electrical signal

to transition states, from the ON state to the OFF state. These state changes may be detected by

the Local Maintenance Shelf 207, and therefore, the associated electrical signals may be

transferred to the RM PU 211. [29] RMPU 211 provides remote monitoring for the light wave inputs (λ, to λ.) into OMU

200. Each optical input (λ) will be associated with a particular port 201. If a problem (i.e., fault)

occurred with an}' of the optical signals, RMPU 211 can detect such an occurrence based on a

stored database 213, which may be located locally or remotely from RMPU 211. Database 213

stores information regarding the mapping of the wavelengths to the input ports of OMU 200,

such that RMPU 211 may identify the port associated with that particular wavelength.

According to one embodiment of the present invention, each wavelength can be associated with a

particular customer; this infonnation may also reside within database 213 and be utilized in the

provisioning process, which is more fully described below with respect to Figure 4. In this

manner, the customer that has traffic associated with the particular wavelength, may be identified

so that the customer can be notified.

[30] Figure 3 shows a flowchart of the monitoring process performed in the system of Figure

2, according to an embodiment of the present invention. In step 301, optical signals are received

at one or more of the input ports 201 of OMU 200. A portion of the received optical signals, as

in step 303, is diverted by splitters 203 to photo diodes 205. Next, the portions of the optical

signals that were split are converted into electrical signals by photo diodes 205, per step 305. In

step 307, the converted electrical signals are transmitted to a remote processor (i.e., remote

monitoring processing unit 211). RMPU 211 then analyzes the electrical signals for any

abnormal condition (step 309); for example, the ON/OFF state transitions indicate problems with

the link that carries the optical signal with the particular wavelength. In step 311, RMPU 211

may send the alarm infonnation to a network management system or to the component that is the

source of the network disturbance. Accordingly, appropriate network restoration can be instituted. Further, the present invention can be employ to assist the provisioning of sendees, as

described below in Figure 4.

[31] Figure 4 shows a flow chart of the provisioning process, according to an embodiment of

the present invention. In an exemplary embodiment, the service provisioning is perfonned at an

operations center by a sendee representative, who has access to the information that is collected

by the processing unit 111. After a potential or existing customer relays the requirements to the

service representative, the service representative selects a route that the customer seeks to

procure capacity on, per step 401. Figure 5A shows an exemplary provisioning screen 500,

which provides a graphical image of the routes of interest that are supported by the optical

network 100. In this example, it is assumed that the customer wants to provision a certain

amount of bandwidth between Los Angeles and New York City. The provisioning screen 500

contains an icon 501 that represents Los Angeles and another icon 503 that represents New York.

Within screen 500, all the available routes corresponding to the source and destination locations

are shown. Under this scenario, two routes, Route A and Route B, exist between LA 501 and

NY 503. Route A provides a direct link, while Route B traverses through Washington, D.C., as

denoted by icon 505. Screen 500 provides a prompt 507, which permits the user to click on

buttons 509 and 511 to select either Route A or Route B, respectively.

[32] Next, in step 403, the capacity along the selected route is examined to determine whether

sufficient capacity exists to satisfy the requirements of the customer. If capacity is available (per

step 405), then the customer is assigned the desired capacity; i.e., an wavelength, λ, is attributed

to the customer (step 407). Figure 5B shows a screen 521 that indicates to the service

representative that the requested capacity is available, as shown in a text box 523. Box 523 may specify any other infonnation with respect to the selected route; for example, if the OMU 107

has conveyed that a fault has occurred, then a message to that effect can be displayed. When

capacity is available, then a prompt 525 is displayed, which requests the customer identification

(ID). The customer ID may be entered using entry box 527. Upon entry of this information,

another screen 531 (as shown in Figure 5C) returns the customer ID in text field 533 and

associated circuit field 535. Screen 531, therefore, serves as a confinnation that the appropriate

capacity has been allocated to the proper customer. It should be noted that the screens 500, 521,

and 531 are exemplary, and that any number of embodiments of the screens can be utilized to

obtain and process provisioning information.

[33] Figure 6 shows a diagram of a computer system that can perform the functions of the

processing unit of Figures 1 and 2. Computer system 601 includes a bus 603 or other

communication mechanism for communicating infonnation, and a processor 605 coupled with

bus 603 for processing the infonnation. Computer system 601 also includes a main memory 607,

such as a random access memory (RAM) or other dynamic storage device, coupled to bus 603 for

storing information and instructions to be executed by processor 605. In addition, main memory

607 may be used for storing temporary variables or other intermediate information during

execution of instructions to be executed by processor 605. Computer system 601 further

includes a read only memory (ROM) 609 or other static storage device coupled to bus 603 for

storing static infonnation and instructions for processor 605. A storage device 611, such as a

magnetic disk or optical disk, is provided and coupled to bus 603 for storing information and

instructions.

[34] Computer system 601 may be coupled via bus 603 to a display 613, such as a cathode ray

tube (CRT), for displaying infonnation to a computer user. An input device 615, including alphanumeric and other keys, is coupled to bus 603 for communicating information and

command selections to processor 605. Another type of user input device is cursor control 617,

such as a mouse, a trackball, or cursor direction keys for communicating direction infonnation

and command selections to processor 605 and for controlling cursor movement on display 613.

[35] According to one embodiment, the detection of network faults is provided by computer

system 601 in response to processor 605 executing one or more sequences of one or more

instructions contained in main memory 607. Such instructions may be read into main memory

607 from another computer-readable medium, such as storage device 611. Execution of the

sequences of instructions contained in main memory 607 causes processor 605 to perform the

process steps described herein. One or more processors in a multi-processing arrangement may

also be employed to execute the sequences of instructions contained in main memory 607. In

alternative embodiments, hard-wired circuitry may be used in place of or in combination with

software instructions. Thus, embodiments are not limited to any specific combination of

hardware circuitry and software.

[36] Further, the instructions relating to the analysis of electrical signals for network faults

may reside on a computer-readable medium. The tenn "computer-readable medium" as used

herein refers to any medium that participates in providing instructions to processor 605 for

execution. Such a medium may take many forms, including but not limited to, non- volatile

media, volatile media, and transmission media. Non- volatile media includes, for example,

optical or magnetic disks, such as storage device 611. Volatile media includes dynamic memory,

such as main memory 607. Transmission media includes coaxial cables, copper wire and fiber

optics, including the wires that comprise bus 603. Transmission media can also take the form of acoustic or light waves, such as those generated during radio wave and infrared data

communications.

[37] Common forms of computer-readable media include, for example, a floppy disk, a

flexible disk, hard disk, magnetic tape, or any other magnetic medium, a CD-ROM, any other

optical medium, punch cards, paper tape, any other physical medium with patterns of holes, a

RAM, a PROM, and EPROM, a FLASH-EPROM, any other memory chip or cartridge, a carrier

wave as described hereinafter, or any other medium from which a computer can read.

[38] Various forms of computer readable media may be involved in carrying one or more

sequences of one or more instructions to processor 605 for execution. For example, the

instructions may initially be carried on a magnetic disk of a remote computer. The remote

computer can load the instructions relating to displaying the GUI screens 500, 521, and 531

remotely into its dynamic memory and send the instructions over a telephone line using a modem. A modem local to computer system 601 can receive the data on the telephone line and

use an infrared transmitter to convert the data to an infrared signal. An infrared detector coupled

to bus 603 can receive the data carried in the infrared signal and place the data on bus 603. Bus

603 carries the data to main memory 607, from which processor 605 retrieves and executes the

instructions. The instructions received by main memory 607 may optionally be stored on storage

device 611 either before or after execution by processor 605.

[39] Computer system 601 also includes a communication interface 619 coupled to bus 603.

Communication interface 619 provides a two-way data communication coupling to a network

link 621 that is connected to a local network 623. For example, communication interface 619

may be a network interface card to attach to any packet switched local area network (LAN). As

another example, communication interface 619 may be an asymmetrical digital subscriber line (ADSL) card, an integrated services digital network (ISDN) card or a modem to provide a data

communication connection to a corresponding type of telephone line. Wireless links may also be

implemented. In any such implementation, communication interface 619 sends and receives

electrical, electromagnetic and/or optical signals that cany digital data streams representing

various types of information.

[40] Network link 621 typically provides data communication through one or more networks

to other data devices. For example, network link 621 may provide a connection through local

network 623 to a host computer 625 or to data equipment operated by a service provider, which

provides data communication services through an IP (Internet Protocol) network 627 (e.g., the

Internet). LAN 623 and IP network 627 both use electrical, electromagnetic or optical signals

that carry digital data streams. The signals through the various networks and the signals on

network link 621 and through communication interface 619, which carry the digital data to and

from computer system 601, are exemplary forms of canier waves transporting the information.

Computer system 601 can transmit notifications and receive data, including program code,

through the network(s), network link 621 and commumcation interface 619.

[41] The techniques described herein provide several advantages over prior approaches to

monitoring optical networks. An optical monitoring unit utilizes optical splitters that receive

optical signals via coiresponding input ports, wherein each of the optical signals has a different

wavelength. The optical monitoring unit also contains photo diodes that are coupled

conespondingly to the optical splitters. The photo diodes receive a portion of each of the optical

signals, which are converted to electrical signals. A processing unit, which may be located

remotely, receives and analyzes the electrical signals for an abnormal condition within the optical network. This arrangement advantageously permits a seivice provider to rapidly respond to

network outages.

[42] Obviously, numerous modifications and variations of the present invention are possible in

light of the above teachings. It is therefore to be understood that within the scope of the

appended claims, the invention may be practiced otherwise than as specifically described herein.

Claims

WHAT IS CLAIMED IS:

1. An apparatus for monitoring a plurality of optical signals, comprising:

a plurality of optical splitters configured to receive the plurality of optical signals, each of

the plurality of optical signals having a different wavelength; and

a plurality of photo diodes coupled correspondingly to the plurality of optical splitters and

configured to receive a portion of each of the optical signals, the portions of the optical signals

being converted to electrical signals,

wherein the electrical signals are transmitted to a processing unit that is configured to

analyze the electrical signals for an abnormal condition.

2. The apparatus according to claim 1, further comprising:

a plurality of input ports coupled to the plurality of optical splitters, wherein the plurality

of input ports correspond with the different wavelengths of the optical signals.

3. The apparatus according to claim 2, wherein the processing unit is coupled to a

database, the database storing a mapping of the wavelengths to the plurality of input ports.

4. The apparatus according to claim 3, wherein the wavelengths corcespond to a plurality

of customers.

5. The apparatus according to claim 3, wherein one of the wavelengths corresponds to a

plurality of customers.

6. The apparatus according to claim 1 , further comprising:

a plurality of input ports coupled to the plurality of optical splitters and configured to

receive optical signals from an optical cross-connect.

7. The apparatus according to claim 1, further comprising: a plurality of input ports coupled to the plurality of optical splitters and configured to

receive optical signals from a plurality of passive optical units.

8. The apparatus according to claim 1, wherein the electrical signals are input to a local

maintenance shelf that detects an ON/OFF state associated with each of the electrical signals.

9. An method for monitoring a plurality of optical signals, the method comprising:

receiving the plurality of optical signals having a different wavelength;

splitting the plurality of optical signals to output portions of the plurality of optical

signals;

converting the portions of the plurality of optical signals into electrical signals;

transmitting the electrical signals to a processing unit; and

analyzing the electrical signals for an abnonnal condition.

10. The method according to claim 8, the different wavelengths of the optical signals in

the receiving step coirespond to a plurality of input ports.

11. The method according to claim 10, wherein the processing unit in the transmitting

step is coupled to a database, the database storing a mapping of the wavelengths to the plurality

of input ports.

12. The method according to claim 11, wherein the database stores customer

infonnation, the method further comprising:

performing service provisioning based upon the customer information stored within the

database.

13. The method according to claim 11, wherein the wavelengths in the receiving step

correspond to a plurality of customers.

14. The method according to claim 11, wherein the wavelengths in the receiving step

coirespond to a plurality of customers.

15. The method according to claim 9, wherein the plurality of optical signals in the

receiving step is output from an optical cross-connect.

16. The method according to claim 9, wherein the plurality of optical signals in the

receiving step is output from a plurality of passive optical units.

17. The method according to claim 9, further comprising:

outputting the electrical signals to a local maintenance shelf that detects an ON/OFF state

associated with each of the electrical signals.

18. A system for monitoring a plurality of optical signals, the system comprising:

an optical monitoring unit configured to receive the plurality of optical signals, the

optical monitoring unit comprising,

a plurality of optical splitters configured to receive the plurality of optical signals,

each of the plurality of optical signals having a different wavelength, and

a plurality of photo diodes coupled conespondingly to the plurality of optical

splitters and configured to receive a portion of each of the optical signals, the portions of

the optical signals being converted to electrical signals; and

a processing unit configured to analyze the electrical signals for an abnormal condition.

19. The system according to claim 18, wherein the optical monitoring unit further

comprises a plurality of input ports coupled to the plurality of optical splitters, wherein the

plurality of input ports correspond with the different wavelengths of the optical signals.

20. The system according to claim 19, further comprising: a database coupled to the processing unit and configured to store a mapping of the

wavelengths to the plurality of input ports.

21. The system according to claim 20, wherein the database stores customer information

that is used to provision services.

22. The system according to claim 20, wherein the wavelengths con-espond to a plurality

of customers.

23. The system according to claim 20, wherein one of the wavelengths corresponds to a

plurality of customers.

24. The system according to claim IS, wherein the optical monitoring unit further

comprises a plurality of input ports coupled to the plurality of optical splitters and configured to

receive optical signals from an optical cross-connect.

25. The system according to claim 18, wherein the optical monitoring unit further

receive optical signals from a plurality of passive optical units.

26. The system according to claim 18, further comprising:

a local maintenance shelf configured to detect an ON/OFF state associated with each of

the electrical signals.

27. A computer-readable medium carrying one or more sequences of one or more

instructions for monitoring a plurality of optical signals, the one or more sequences of one or

more instructions including instructions which, when executed by one or more processors, cause

the one or more processors to perfonn the steps of: receiving electrical signals from an optical monitoring unit having a plurality of input

ports, the received electrical signals being converted from a plurality of optical signals having a

different wavelength;

analyzing the electrical signals for an abnonnal condition; and

selectively generating an alann signal in response to the analyzing step.

28. The computer readable-medium according to claim 27, the different wavelengths of

the optical signals in the receiving step corcespond to a plurality of input ports.

29. The computer readable-medium according to claim 2S, wherein the one or more

processors are further configured to perform the step of:

retrieving information that maps the wavelengths to the plurality of input ports from a

database.

30. The computer readable-medium according to claim 29, wherein database in the

retrieving step stores customer information that is used to provision services.

31. The computer readable-medium according to claim 29, wherein the wavelengths in

the receiving step coirespond to a plurality of customers.

32. The computer readable-medium according to claim 29, wherein one of the

wavelengths in the receiving step corresponds to a plurality of customers.

33. The computer readable-medium according to claim 27, wherein the plurality of

optical signals in the receiving step is output from an optical cross-connect.

34. The computer readable-medium according to claim 27, wherein the plurality of

optical signals in the receiving step is output from a plurality of passive optical units.

35. The computer readable-medium according to claim 27, wherein the electrical signals

in the receiving step is transmitted from a local maintenance shelf that detects an ON/OFF state

associated with each of the electrical signals.

36. An apparatus for monitoring a plurality of optical signals, comprising:

means for receiving the plurality of optical signals having a different wavelength;

means for splitting the plurality of optical signals to output portions of the plurality of

optical signals;

means for converting the portions of the plurality of optical signals into electrical signals;

means for transmitting the electrical signals to a processing unit; and

means for analyzing the electrical signals for an abnormal condition.

37. The apparatus according to claim 36, the different wavelengths of the optical signals

correspond to a plurality of input ports.

38. The apparatus according to claim 37, wherein the processing unit is coupled to a

39. The apparatus according to claim 38, wherein the database stores customer

infonnation that is used for provisioning of services.

40. The apparatus according to. claim 38, wherein the wavelengths coirespond to a

plurality of customers.

41. The apparatus according to claim 38, wherein one of the wavelengths corresponds to

a plurality of customers.

42. The apparatus according to claim 36, wherein the plurality of optical signals is output

from an optical cross-connect.

43. The apparatus according to claim 36, wherein the plurality of optical signals is output

from a plurality of passive optical units.

44. The apparatus according to claim 36, further comprising:

means for outputting the electrical signals to a local maintenance shelf that detects an ON/OFF state associated with each of the electrical signals.