CA2316856A1 - Method and system for restoring coincident line and facility failures - Google Patents
Method and system for restoring coincident line and facility failures Download PDFInfo
- Publication number
- CA2316856A1 CA2316856A1 CA002316856A CA2316856A CA2316856A1 CA 2316856 A1 CA2316856 A1 CA 2316856A1 CA 002316856 A CA002316856 A CA 002316856A CA 2316856 A CA2316856 A CA 2316856A CA 2316856 A1 CA2316856 A1 CA 2316856A1
- Authority
- CA
- Canada
- Prior art keywords
- failure
- facility type
- previous
- determining
- restoration
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
Classifications
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04Q—SELECTING
- H04Q11/00—Selecting arrangements for multiplex systems
- H04Q11/0001—Selecting arrangements for multiplex systems using optical switching
- H04Q11/0062—Network aspects
Abstract
The system and method of the present invention provide restoration of coincident line and facility failures. The system of the present invention includes light termination equipment (LTE, 106, 114) that is capable of detecting failures, determining the type of component that failed, determining which restoration facility to use based on the type of component that failed, and providing restoration. The system of the present invention also includes spare capacity for restoration, including protect channels (212) and an optical restoration network (110). In addition, the system of the present invention includes an optical cross connect switch (OCCS, 108, 112) that is capable of switching electrical signals to the optical restoration network (110). The method of the present invention also involves detecting a failure, determining the type of component that failed, and sending an alarm to a centralized management center.
Description
wo ~r~asao rc~rnrs9an~r~o METHOD AND SYSTEM FOR RESTORING COINCIDENT
LINE AND FACILITY FAILURES
The present invention relates generally to the reliability and restoration of optical transmission systems.
Telecommunications networks that carry telephone calls and. data include interconnected components that process calls and transfer data.
Optical transmission lines or links interconnect the components. Rather than having single optical transmission lines interconnecting call processing and data transfer components, the components may be interconnected by an optical network.
High speed data is modulated on light waves which are transmitted through the optical network. Any type of data can be carried over an optical link, including but not limited to speech, data input into or retrieved by a computer or computer database, and any digital data. Fiber optic cables carry far greater amounts of digital data than conventional electrical cables. A single fiber operating at approximately 10 Gigabits/second (Gb/s) and transmitting data according to a high-speed synchronous digital hierarchy standard, such as the SONET OC-192 protocol, carries a data equivalent to 129,024 voice calls.
Further bandwidth improvement can be achieved by modulating different electrical data signals on distinct light wave carriers having different frequencies. This technique is known as wavelength division.multiplexing (WDM). Optical systems using WDM
requixe optical transmitters and receivers that operate at different light wave frequencies. The optical transmission line, connecting an optical transmitter and receiver, can propagate many light wave signals of different frequencies simultaneously. For example, 16 OC-192 erbium~band~channels can be carried on a single S fiber pair with WDM.
Thus, fiber optic communications links, especially WDM communication links, carry vast amounts of information among distant sites to accomplish data, voice. and image connectivity over a large geographical area. Optical transmission lines, transmitters and receivers, however, can fail. The failure of such components can have a substantial economic and practical impact on network users and network service providers. Therefore, in designing communications networks, special measures are practiced to assure utmost reliability of network components and survivability in the~event of a failure.
Two types of failures experienced in a telecommunications network are line failures and module failures. A channel in a telecommunications network has a transmitter and a receiver, which are also referred to as modules, and a line between the transmitter and receiver. Line failures impair the optical communications line between two sites. Line failures include 'damage to the physical fiber and optical component failure, such as the malfunction of amplification equipment situated along the physical path of the fiber, optic cable. Line failures impair the communications line between two network sites. In contrast, a failure of the transmit or receive equipment housed at either end of an optical communications link is referred to as a module failure.
Both line failures and module failures disable the channel.
In the event of either a line or module failure,,restoration techniques are used to restore the traffic temporarily until the failure is repaired. The restoration approach varies depending on the failure.
Traffic may be restored using line protect switching (LPS)~or network restorative switching (NRS). If the traffic is restored using LPS, light termination equipment (LTE) switches the signal from the failed channel to a spare.channel within the LTE. If the traffic is restoxed using NRS, traffic is rerouted by switching the traffic to different routes either manually, based on information stored in switch tables or a pre-planned algorithm stored in the switch.
LPS ensures resiliency to fiber cuts by employing a spare channel, referred to as the protect channel, that normally does not carry traffic but may be used as a back-up should a channel in use fail. The protect channel is on a different path in order to reduce the likelihood that the protect channel will experience the same failure as the channel in use.
Creating and maintaining idle spare capacity is costly.
In order to reduce costs, one spare channel is available for restoration of multiple traffic carrying channels. When one protect channel is available to restore multiple traffic carrying channels, LPS cannot restore a failure of more than one traffic carrying channel. LPS is primarily aimed at restoring single channel failures and is implemented within LTE which is the local equipment that terminates the fiber optic cable. Since LPS is localized and simple, it is also very fast requiring 'only tens of milliseconds for restoring a failed communications link.
Because telecommunications networks include high capacity optical cables such as WDM, the networks are susceptible t.o failures that disable a very large number o~ channels and which cannot be restored by LPS
alone causing potential high volumes of traffic loss and significant economic impact. Accordingly, NRS is used to restore optical networks. Exchanges have the capability to reroute traffic automatically using switch table's or an algorithm to other transmission paths in the network. Exchanges which have switching capability are connected to LTE at each site and to other transmission paths in the network. When a fiber cut or other major fiber failure occurs disabling a span including a large number of telecommunications links between two switching nodes, NRS is employed by the exchange to reroute the traffic through the restoration network to circumvent the failure until repairs 'are completed.
Line protect switching (LPS) and network restorative switching (NRS) have separate but complementary roles in a modem network design. The LPS
can quickly restore simple localized failures without having to invoke the more complex NRS. In many applications, the LPS can switch traffic without causing any significant interruption to traffic. The NRS can handle network problems of a larger scope.
However, current LPS techniques do not allow for the restoration of failures that involve more than one channel. Although current LPS reroutes the traffic to a spare protect channel, only one protect channel is available to restore multiple channels. Therefore, if the protect channel is in use restoring a failure, subsequent failures cannot be restored using LPS.
In addition, current NRS does not allow for restoration by components in the optical network via a restoration network. NRS is currently employed by exchanges commonly used to provide access to the telecommunications network and switch calls to an appropriate destination rather than by components in the optical network. As a result, switching to an alternate path is, limited to exchange locations which are often housed proximate to areas of access to other telecommunications networks and private customers' termination equipment rather than near transmission path cross connect sites within the optical network.
In addition, NRS reroutes traffic to other traffic carrying channels. If traffic volumes are high, as they may be during certain hours of the day and certain days of the year, the network may have insufficient capacity~to handle both the traffic that was allocated for the traffic carrying channels and the restoration traf f is .
In the present invention, light termination equipment (LTE) sends an alarm to an optical cross connect switch (OCCS) controller to restore a failure when a protect channel is in use. The OCCS controller controls multiple optical cross connect switches (OCCSs) and addresses alarms by determining whether they can be restored. An OCCS is an optical switching device that interconnects numerous optical transmission lines to an optical restoration network. An optical restoration network .includes complete restorative spans of telecommunications links connected by the OCCSs.
The system of the present invention includes LTE, an OCCS, and an OCCS controller that are capable of restoring a second failure within one telecommunications cable. The LTE of the present invention can reroute optical and electrical signals to compensate for a failed component such as an optical transmitter, receiver, or transmission line. The present invention includes a protect, or spare, optical transmission line with which to replace a corresponding failed channel. The LTE can switch to the protect channel.when a channel fails due to either line or module failure. The LTE of the present invention is also capable of determining the facility type of channel failures and.sending an alarm to the OCCS to reroute failure of a line via the optical restoration network~if one o~ the two failures is a line failure.
The OCCS of the present invention can reroute optical and electrical signals to compensate for a channel that experiences line failure. However, the OCCS~cannot restore a channel that experiences module failure. As a result, when two coincident failures, a line and facility failure, occur the present invention restores the line failure via the first OCCS switching and restores the.module failure using the protect channel.
The OCCS controller of the present invention is capable of receiving the alarm from the LTE
notifying of a failure and sending a request to the OCCS to .restore a failed line through the optical restoration network.
. The method of restoring coincident line and facility failures is employed when a subsequent failure is detected. The subsequent failure is analyzed to determine the facility type of the failure. If the subsequent failure~is due to a line failure, an alarm is sent to the OCCS and the subsequent failure is restored~via the optical restoration network. If the subsequent failure is due to a module failure, the facility type of the previous failure is determined.
If the facility type of the previous failure is failure of a line, an alarm is sent to the OCCS and the previous failure is restored via the optical restoration network. If the facility type of the previous failure is also failure of a module, an alarm is sent to thevnetwork management center indicating that a' non-restorable failure has occurred.
. Further features and advantages of the invention, as well as the structure and operation of PC'f/US98/27~20 various embodiments~of the invention, are described in detail below with reference to the accompanying drawings.
The present invention is described with reference to the accompanying drawings, wherein:
Figure 1 is a block diagram of an optical restoration environment according to one embodiment of the.present invention;
. Figure 2 is a block diagram of an optical cross connect according to one embodiment of the present invention;
Figure 3 is a flowchart of the operation of the optical cross connect according to one embodiment of the present invention;
Figure 4A~is a block diagram of the optical cross.. connect illustrating the use of a protect channel to restore a single line failure according to one embodiment of the present invention;
Figure 4B is a block diagram of the optical cross connect illustrating the response to a first and second line failure according to one embodiment of the present invention;
Figure 4C is a block diagram of the optical cross connect illustrating the response to a second module failure and first line failure according to one embodiment of the~present invention; and Figure 5 is a block diagram of an optical cross connect switch.controller according to one embodiment of the present invention.
In the drawings, like reference numbers generally indicate identical, functionally similar, and/or structurally similar elements. The drawing in which~an element first appears is indicated by the leftmost digits) in the corresponding reference number.
The present invention provides a system and method of restoring subsequent failures within a telecbmmunications network. A system and method are provided. for sending an alarm from light termination equipment (LTE) to an optical cross connect switch (OCCS) controller. The OCCS controller addresses the alarm by determining whether to restore the failure by sending a command to an optical cross connect switch (OCCS). The OCCS controller can identify the facility type of the subsequent failure and retrieve the facility type of previous failures in order to ensure that a protect or spare channel is made available to IS restore a module failure in the event restoration of a module failure is needed.
The system and method of the present invention is illustrated as operating in an exemplary telecommunications network that carries digitized voice between two individuals speaking on telephones. The present invention is further illustrated within an exemplary optical cross connect network that is within the telecommunications network. However, the present invention is not limited to these environments and may be used in any network that requires restoration such as an X.25 network transmitting data.
Provided below is a brief description of the terminology used within this document. Additional description is provided in the following sections along with exemplary implementations and embodiments.
However, the present invention is not limited to the exemplary implementations and embodiments provided.
A "telecommunications network" is a network that carries information. The information may be digitized voice that is carried between two telephones or data that is carried between two computers. Several examples of telecommunications networks follow in the description of FIG. 1, however, a telecommunications network is not limited to these examples.
A telecommunications network may include termination equipment, optical cross connect switches, and optical cross connect switch controllers.
"Termination equipment" is equipment that terminates a cable within a telecommunications network and typically provides modulation and demodulation functionality.
Exemplary termination equipment is light termination equipment described further with respect to FIG. 1 and FIG. 2.
An "optical cross connect switch" provides switching functionality within an optical network. An optical network is a network within a telecommunications network that is comprised of transmission facilities that carry optical signals. An optical network may provide high speed transmission and be capable of carrying a significant amount of data.
"Optical cross connect switch controllers"
accept information from termination equipment and use the information to provide commands to optical cross connect switches. Optical cross connect switch controllers are processors with access to memory via a separate,or an associated memory storage device such as a hard drive, disk,. and/or standalone database.
However, an optical~cross connect switch controller is not limited to.these embodiments and may be any capability to control one or more optical cross connect switches. More detail is given about optical cross connect switch controllers below.
A "failure" is a component that experiences operational difficulties within the telecommunications network.' A disabling event causes the failure of one or more components vuithin the telecommunications network. If multiple failures occur, after the first failure. occurs, a later failure is referred to as a "subsequent failure" and the first failure or a previous failure is referred to as a "previous failure.."
Components within the telecommunications network can be~grouped into types of components, such as lines and modules. The failed component is a type of component which is the "failed facility type." A
previous failed component is also a type of component which is the "previous failed facility type." Two failed facility types and previous failed facility types are a "line failure" which is a failure of a line type component and a "module failure" which is a failure of a module or equipment type component.
FIG. 1 is a block diagram of an optical restoration environment 101 according to one embodiment of the present invention. Optical restoration environment 101 provides connectivity and switching capability for telecommunications services. An exemplary use for the optical restoration environment 101 is to restore channels in a network carrying a call placed by a caller on a first telephone 102 to a receiver~on a second telephone 120. However, optical restoration'environment 101 may be used to restore any voice or data traffic carried on a network.
Optical. restoration environment 101 includes a first telephone 102 used by a caller that is interconnected to a'second telephone 120 used by a receiver via a telecommunications network 122.
Telecommunications network 122 includes a first exchange,104, an optical cross connect 116, a second exchange 118, and an optical restoration network 110.
The first telephone 102 is connected to a first exchange 104 within the telecommunications network 122. The first exchange 104 provides switching functionality to connect to the appropriate telecommunications channel to establish service to the second telephone 120. The first exchange 104 is connected to optical cross connect 116 which is equipment that provides termination and optical switching for channels carried on an optical telecommunications 'cable 113. In addition, the optical cross connect 116 is connected to a second exchange 118 in order to establish connectivity via a channel link between the first telephone 102 and the second telephone 120. The second exchange 118 is connected to the second telephone 120 to provide switching and connectivity to second telephone 120.
According to the present invention, the optical~cross connect 116 is also connected to the optical restoration network 110 to provide restoration in the event of channel or cable failure. The optical cross. connect 116 includes a first light termination equipment (LTE) 106 and second LTE 114. The optical cross connect 116 also includes a first optical cross connect switch (OCCS) 108 and a second OCCS 112. The first exchange 104 is connected to the first LTE 106.
The first LTE 106 handles call termination, data rate conversion, and light protect switching (LPS) restoration functions. The first LTE 106 is connected to the first OCCS 108. The first OCCS 108 provides optical switching capability needed for network restoration switching (NRS) via the optical restoration network 110. The 'first OCCS 108 is connected to a second OCCS 112, for connectivity to the second telephone 120. The path between the first OCCS 108 and the second OCCS 112 is illustrative only. As would be apparent to~a person skilled in the art, additional intermediate optical cross-connect switches and filters can be added in a point-to-point circuit or any network topology~(eg. ring, mesh). In addition, the optical cross connect 116 includes an optical cross connect switch (OCCS) controller 111 which is connected to the first LTE 106,~the second LTE 114, the first OCCS 108, and the second OCCS 112 to provide control and allow for rerouting via the optical restoration network 110.
The first telephone 102 and second telephone 120 are used to place and receive calls via the telecommunications network 122. The first telephone 102 and second telephone 120 are exemplary and may be any equipment that can be used to initiate or receive a call.via a telecommunications network 122. Examples of other types of equipment that can be used to initiate and receive a call via the telecommunications network 122 are a wireless telephone, a pager, a personal computer and a modem.
The first exchange 104 and second exchange 118 are exemplary exchanges within the telecbmmunications network 122. The first exchange 204 and second exchange.118 provide switching capability to route a call via a telecommunications link that interconnects to the caller s destination. The first exchange 104 and second exchange 118 may be implemented PC"T/US98127720 using DMS-250 switches manufactured by Nortel.
The telecommunications network 122 may comprise many telecommunications networks including local exchange networks and interexchange networks.
Typically, equipment used to initiate and receive a call, such as.first telephone 102 and second telephone 120, is interconnected to an exchange within a local exchange network. Therefore, exemplary first exchange 102 and second exchange 118 are within~a local exchange network. A local exchange network comprises switches and termination equipment within a localized area. An example of a local exchange network is a local telephone operating company network such as Bell Atlantic. If the caller is calling long distance, the local exchange network will send the call to an interexchange switch in an interexchange network.
Similar to the local exchange network, an interexchange network comprises a plurality of switches, also referred to as exchanges, that are located throughout a geographic area. However, interexchange networks typically comprise of switches throughout a large geographic area to process long-distance telephone calls. For example, a national interexchange network comprises switches located throughout the nation. When a call is routed to the interexchange network, it may be routed to one or more switches within the interexchange network.
Optical cross connect equipment, such as exemplary optical.cross connect 116, is connected to the telecommunications cables within telecommunications network 122,.such.as exemplary telecommunications cable 113 between the first exchange 104 and second exchange 118. The optical cross connect 116 provides WO 99134540 PCTIUS98l27720 termination and switching functionality for signals carried bn optical telecommunication cable 113.
The optical cross connect 116 includes a first LTE 106 and a second LTE 114. The first LTE 106 S and second LTE 114 terminate the telecommunications cable 113. The first LTE 106 and second LTE 114 will be described in further detail with respect to FIG. 2.
The optical cross connect 116 includes a first,OCCS 108 and a second OCCS 112. The first OCCS
108 and second OCCS 112 can by any type of optical switch. For example, the first OCCS 108 and second OCCS~112 may be implemented using combinations of an integrated lithium niobate directional-coupler type switch. Other types of suitable optical switching technology include switches based on thermo-optic effect in polymer waveguides or silica glass, semiconductor amplification, piezo movement, and integrated indium phosphide. In addition, although a single first OCCS 108 and second OCCS 1I2 are shown for clarity', multiple discrete switches and couplers can be used to perform equivalent multiple-port optical switching.
The OCCS reroutes traffic based on an algorithm. An exemplary algorithm is the Real-Time Multiple. Wavelength Routing (RMWR) algorithm which uses collected data to~select an alternate path based on wavelength information stored in a centralized database'. An additional description of an algorithm used for rerouting traffic is described in U.S. Patent No. 4,956,835 entitled, "Method and Apparatus for Self-Restoririg and Self-Pxovisioning Communication Networks"
filed by Grover.
The first OCCS 108 and second OCCS 112 are connected to a telecommunications cable 113. The telecommunications cable 113 includes bidirectional optical fibers, line repeaters, and/or amplifiers.
Alternatively, the telecommunications cable 113 may include long-haul., single mode fiber. The telecommunications cable 113 is not linked to these components and may be any transmission medium cable of carrying signals in a telecommunications network.
The optical restoration network 110 is connected to the~first OCCS 108 and the second OCCS
112. The optical restoration network 110 comprises spare optical termination and cross connect equipment for restoration of traffic if the optical cross connect 116 in use fails. The optical restoration network 110 includes a plurality of spare components including LTEs, such as the. first LTE 106 and the second LTE 114, OCCSs, such as the first OCCS 108 and second OCCS 112, and telecommunications cables, such as telecommunications cable 113.
' The OCCS controller 114 is connected to the first LTE 106, the 'second LTE 114, the first OCCS 108, and the second OCCS 112. The OCCS controller 121 can be connected to any number of LTE and OCCSs. The OCCS
controller 111 receives information from the first LTE
106 and the second LTE 114. If the information indicates that traffic must be rerouted, the OCCS
controller 111 sends commands to the first OCCS 108 to reroute electrical signals via the optical restoration network 110. The~OCCS controller 111 may be implemented using any processor or a plurality of distributed processors that are coordinated by a communication link not shown.
FIG. 2 is a block diagram of optical cross connect 116. Illustrated within the first LTE 106 and the second LTE 114 are the transmitters, 206A, 2068, 206C, .. 206n, and the receivers, 210A, 2108, 210C,...
210n. Each one of the transmitters 206 is connected to a corresponding one of the receivers 210 via one of multiple channels.214A, 2148, 214C, ... 214n within the telecommunications cable 113. Also within telecommunications~cable 113 is a protect channel 212.
The protect channel 212 is spare and is used for restoration if one,of the channels 214 in use fails.
The protect channel 212 is connected to a transmitter 204 within the first LTE 106 and a receiver 208 within the second LTE 114.
Although, both first LTE 106 and second LTE
IS 114 have-transmitters and receivers, transmitters 206 are shown only in the first LTE 106 and receivers 210 are shown only in~the second LTE 114 for clarity. The transmitters and receivers are typically in an array made up of pairs of transmitters and receivers. In FIG. 2, each of the:transmitters 206 would actually be a transmit and receive pair.
Each.of the transmitters 206 transmit a signal carrying a digitized voice of a caller or any other data that was sent by equipment that originated a call, which is. shown in FIG. 1 as exemplary first telephone 102. In one embodiment, the transmitters 206 are modulated lasers, such as directly modulated semiconductor laser diodes or externally modulated lasers. Each one of the transmitters 206 is connected to one of the multiple channels 214 within the telecommunications cable 113. The transmitters 206 transmit signals via the channels 214 within the telecommunications cable 113 to the receivers 210.
WO 99!34540 PCTNS981Z7720 Similar to the transmitters 206, each one of the receivers 220 is connected to one of the multiple channels 214 within telecommunications cable 113 to receive.signals from the corresponding one of the transmitters 206. The receivers 210 demodulate electrical signals from the light wave signal of the corresponding carrier frequency. Receivers 210 can be optical detectors or any equipment that can receive and transduce the transmitted signal.
In one example, each one of the channels 214 within telecommunications cable 113 is an optical channel within a fiber optic cable. The signals within an optical fiber are modulated using various frequencies which allow one fiber optic cable to carry a large number of channels. As mentioned above, this technique is referred to as wavelength division multiplexing (WDM). Further description of transmitters, receivers, and fiber optic cables is given by Daniel Minoli in chapter 7 of his book entitled, "Telecommunications Technology Handbook,"
Artech House, Inc. (1991).
Each of~the channels 214 (also referred to as traffic carrying channels) carry normal non-restoration traffic within the telecommunications cable 123. The protect channel 212 is an optical channel within a fiber optic cable that is achieved by modulating a signal. at a particular frequency. Also, the transmitter 204 that transmits via the protect channel 212 is a modulated laser like the transmitters 206 on the other channels 214. The transmitter 204 may be implemented using the same technologies as the transmitters 206 on the other channels 214 within the telecommunications cable 113. Like the receivers 210 that receive signals from the traffic carrying channels 214, the receiver 208 on the protect channel 212 demodulates the received signal. The receiver 208 may be implemented with the same technologies as the receivers 210 that receive signals from the other channels 214.
Both the first LTE 106 and the second LTE 114 have processors referred to as the first LTE processor 216_and the second LTE processor 228, respectively.
l0 The first LTE processor 216 is connected to each of the transmitters 206 to obtain information about whether each of the transmitters 206 is in use and whether the transmitters 206 are experiencing operational difficulties. Similarly, the second LTE processor 218 is connected to each of the receivers 210 to obtain information about whether each of the receivers 210 is in use and whether the receivers 210 are experiencing operational difficulties. The first LTE processor 216 and the second LTE processor 218 are connected to the protect channel transmitter 204 and protect channel receiver 208,, respectively to obtain information about whether the protect channel 212 is in use and whether the protect channel is experiencing any operational difficulties. The first LTE processor 216 and second LTE processor 218 are any processor that can obtain information from and coordinate among the components with a first LTE 106 or second LTE 114.
FIG. 3 illustrates a restoration process 301 according to the present invention. FIG. 3 will be described with reference to the example of FIGS. 4A, 4B,~and 4C which illustrate various failures of channels 214 within telecommunications cable 113.
In step 304, either the first LTE 106 or the second LTE 114 detects a failure 404 in channel 214A.
The first LTE 106 may detect a failed transmitted 206.
A single optical detector at the second LTE 114 can detect a failure and send a fault signal to the second LTE processor 210 within the second LTE 114. Failure 404 may be detected electrically at first LTE 106 using conventional loss o~f signal techniques. Alternatively, failures may be detected by multiple optical detectors (not shown) along the channels 214. If an optical detector~detects a failure on one of the channels 214, the optical detector will send a fault signal to the first LTE 106.. Various methods of optical failure detection including optical and electrical detection techniques can be used.
In step 306, either the first LTE 106 or the second LTE 114, whichever detected the failure, determines whether the protect channel 212 is in use.
A determination of whether the protect channel 212 is in use is made to'evaluate whether the protect channel 212 'is available to restore the detected failure. FIG.
4A illustrates a single line failure in which the protect channel is available to restore the detected failure 404. If the protect channel 212 is not in use, the protect channel 212 is available to restore the detected failure 404 and the first LTE 106 proceeds to step 308. If the protect channel 212 is in use, the first LTE 106 proceeds to step 309 and sends an alarm to the OCCS controller 111.
In step 308, traffic is restored by the first LTE 106 on the protect channel 212. FIG. 4A
illustrates using the protect channel 212 to circumvent the single line failure 404. The incoming line to the first channel 214A is interconnected to the protect channel transmitter 204 rather than the first channel transmitter 206A: The protect channel 212 provides connectivity that~circumvents the failed channel 214A.
The protect channel receiver 208 within the second LTE
114 receives tl~e signal and sends the signal to the next component that will receive the signal and provide connectivity to the final destination, for example the second exchange 118 as shown in FIG. 1.
FIGS. 4B_and 4C illustrate multiple failures within telecommunications cable 113. If the protect channel 212 is in use, step 309 is performed to restore the detected failure. In step 309, the first LTE 106 or second LTE 114, whichever detected failure 404, sends an alarm to the OCCS controller 111. The information is,sent by ffirst LTE processor 216 or the second LTE processor 218. The first LTE processor 216 obtains the information from one of the transmitters 206. The second LTE processor 218 obtains the information from one of the receivers 210. The first LTE processor 216 and the second LTE processor 218 send the OCCS controller 111 information including whether the failure is a line failure or a module failure.
A failure on a channel 224 may be either a line failure or a module failure. A line failure is a failure of the channel 214 between the transmitter 206 and the receiver 210. FiG. 4B illustrates a first line failure 404 and a second line failure 406.
Transmitters 206 and receivers 210 are also referred to as modules. A module failure is a failure of either a transmitter 206 or a receiver 210. FIG. 4C illustrates a first line failure 404 and a second module failure 420.
The first LTE processor 216 can determine if the transmitters 206 (or associated receivers or modules not shown but collocated with each of the transmitters 206 iaithin the first LTE 106) fail. The second LTE processor 218 can determine if the receivers 210 (or associated transmitters or modules not shown but collocated with each of the receivers 210 within the second LTE 114) .fail. If a transmitter, receiver, or other module fails, a module failure, also referred to as an equipment failure has occurred. Both the i0 first LTE processor 216 and the second LTE processor 218 can report to~the OCCS controller 111 that a module failure occurred. If a line failure occurs, the photodetector within the one of the receivers 210 that corresponds to the failed channel will detect a loss of light and the second LTE processor 218 can determine that a line failure occurred and report that a line failure occurred to .the OCCS controller 111.
If a line failure occurs, two alarms may be sent to the OCCS controller 111. A photodiode within the second LTE 114 may detect a failure by detecting a loss of light and a receiver associated with transmitter 206 may detect a loss of communication with the second LTE 124.. If both the first~LTE 106 and the second LTE 114 send alarms for the same failure, the OCCS controller 211 can coordinate the alarms and determine that one failure occurred.
In step 310, the OCCS controller 111 identifies the type of the new failure using the information received from the first LTE 106 and/or the second LTE 114. The type of failure, either line or module, is determined in order to determine how to restore the failure.. According to the present invention, line failures, such as first line failure 404 and second line~failure 406, are restored either on the protect channel 212 or via the optical restoration network 110. The~first LTE 106 restores a single module failure 410 on a protect channel 212 as described earlier with respect to steps 306 and 308.
If multiple failures occur and the protect channel 212 capacity is insufficient to restore all of the failures, in step 310 the type of failure is determined in order to ensure that if the multiple failures include a module failure 410 and line failures, such as first line failure 404 and second line failure 406, the module failure.is restored on the protect channel 212 and the line failures are restored on the optical restoration network 110.
If .the type of new failure is a line failure, the OCCS controller 111 proceeds to step 312 to provide restoration through OCCS restoration actions using the optical restoration network 110. If the type of new failure is a module failure, the OCCS controller 111 proceeds to step 314 to obtain additional information in order to determine how to restore the failure.
In step .312, the OCCS controller 111 sends a command to the first OCCS 108 to restore the new failure.. If the new failure is a second line failure 406 as illustrated in FIG. 4B, then the second line failure 406 can be restored on the optical restoration network 110. Determining the facility type and rerouting the previous failure 404 are unnecessary because the second line failure 406 can be restored without affecting the previous failure 404.
The second.line failure 406 is restored by the OCCS controller 111 sending an alarm to the first OCCS 108. When the first OCCS 108 receives the alarm, the first OCCS 108 switches to reroute the optical electrical signals that were to be carried on the failed channel 214C via the optical restoration network 110.~~The optical electrical signals take a path from S the transmitter 206C within the first LTE 106 through the first OCCS 108 through a path 408 in optical restoration network. 110 to the second OCCS 114 which is connected to the receiver 210C within the second LTE
114 that receives the signal. When the second line failure 406 is repaired, the first OCCS 108 will reroute the electrical signals back to channel 214C.
In step 314, the OCCS controller 111 retrieves the type of previous failure. The OCCS
controller 111 retrieves the information from the first LTE processor 216 or the second LTE processor 218 that indicates whether the previous failure was a line failure or a module failure. The type of the previous failure indicates the type of failure that is being restored using the protect channel. As mentioned previously, although line failures, such as first~line failure 404 and second line failure 406 typically can be restored on a protect channel 212 or via an optical restoration netiwork 110, a single module failure 410 often can only be restored on a protect channel 212.
Therefore, if the new failure is a module failure 410 as was determined in step 312 and is illustrated in FIG. 4C, then determining the type of the previous failure 404 indicates whether the restoration in use for the previous failure 404 can be modified to accommodate the new. failure 410.
If the type of previous failure is a line failure as is illustrated in FIG. 4C, then the OCCS
controller 111 proceeds to step 318 to restore both the previous failure 404 and the new failure 410. If the type of previous failure is a module failure which is not shoc~n, then OCCS controller 111 proceeds to step 316 to send an alarm because neither the OCCS
controller 111 or~the first OCCS 108 can restore both the previous failure and the new failure.
In step 316, the OCCS controller 111 sends an alarm to a national network management center (NNMC) or other centralized or regional fault reporting center to report an unrestorable failure. If the new failure is a module.failure, such as module failure 410 shown in FIG. 4C, and the previous failure is a module failure then two module failures have occurred but only one protect channel 212 is available for restoration.
Assuming one protect channel is available and no other restoration technique can be used to in order to enable the optical cross connect 116 to restore the second module failure, the OCCS controller 121 sends an alarm to a fault reporting~center such as the NNMC to report an unrestorable failure.
The NNMC has staff and computer systems to detect and restore failures that cannot be restored with the automated systems in the telecommunications network 122. Computer systems in the NNMC may provide restoration automatically by rerouting traffic using switching tables ~ntithin exchanges, such as first exchange 104 and second exchange 118. If automated computer systems do not automatically provide reroutes, they may provide information to staff that manually implements changes to the software to reroute traffic.
For example, if multiple faults occur on telecommunications cable 113 that cannot be restored, either~computer systems or staff may modify the switch WO 99!34540 PCTNS98/Z7720 tables in first exchange 104 to send the traffic via different communications links until telecommunications cable 113 is repaired. However, if the failure is limited to one second module failure, the NNMC may do nothing or simply block traffic from attempting to use the channel 214C that cannot be restored until the channel 214C is repaired. Often all channels 214 within a telecommunications cable 113 are not in use so new calls can use the remaining channels 214A, 2148, ... 214n.
In step 318, the OCCS controller 111 sends a command~to the first OCCS 108 to reroute the previous line failure 404. After the previous line failure 404 has.been rerouted by the first OCCS 108, the OCCS
controller 111 sends a command to the first LTE 106 to switch the electrical signals that were carried on the second failed channel 214C to the protect channel 212 to restore the new module failure 410.
If the OCCS controller 111 performs step 318, then in step 310, the OCCS controller 111 identified that~~the new failure was a module failure 410, and in step 314, the OCCS controller 111 retrieved information indicating that the previous failure was a line failure 404. As mentioned previously, the scenario of a previous first line failure 404 and a new module failure 410 is illustrated in FIG. 4C. If the optical cross connect 416 cannot restore single module failures via .the optical restoration network 110, then the OCCS
controller 111 can only restore the new module failure 410 using the protect channel 212. As a result, restoration by the OCCS controller 111 of both the first line failure 404 and the module failure 410 is possible only if the first line failure is rerouted to the optical restoration network 110 by sending an alarm to the first OCCS 108.
The OCCS controller 111 sends a command to the first OCCS 108 to reroute the previous first line failure 404 via the optical restoration network 110.
The OCCS controller 111 may restore any number of line failures'by sending alarms to the first OCCS 108 which will reroute the electric signals via the optical restoration network. In other words, if channels 214A, 214B~, and 214D experience line failures prior to channel 214C experiencing a module failure, each line failure would have.been restored by the OCCS controller 111 performing earlier steps in the operation of optical termination and cross connect equipment 301 when~each failure wa.s experienced. The result would be that the first line failure would be restored on the protect channel 212 by the OCCS controller 1I1 performing steps 304, 306, and 308 and subsequent line failures would be restored via the optical restoration network 110 by the OCCS controller 111 performing steps 306, 309, 310, and 312. However, regardless of the number of line failures restored via the optical restoration network 110, when a module failure 410 is detected, if a line failure 404 is restored on the protect channel 212,.the line failure 404 is rerouted via the optical restoration network 110 to make the protect channel 212 available to restore the module failure 410. After the line failure 404 is restored by the first OCCS 108 via the optical restoration network, the first LTE 106 switches the electrical signals that were carried on channel 214C that experienced the module failure 410 to the protect channel 212.
The OCCS controller 111 of the present invention is preferably implemented using a computer system 502 as shown in block diagram form in FIG. 5.
The computer system 502 includes one or more processors, such as processor 506 connected to bus 504.
Also.cannected to bus 504 is main memory 508 (preferably random access memory, RAM) and secondary storage devices 510. The secondary storage devices 510 include, for example, a hard drive 512 and a removable storage medium drive 514 (such as a disk drive, for example) .
The functionality of the OCCS controller 111 is preferably performed by a computer program that resides in main memory 508 while executing. When executing, this computer program enables the computer system 502 to perform the features of the present invention as discussed herein. Thus, the OCCS controller 111 represents a controller of the computer system 502 (and of the processor 506). Alternatively, the functionality of the OCCS controller 111 is predominately or entirely performed by a hardware device, such as a hardware state machine.
. ~ In one embodiment, the present invention is a computer program product (such as removable storage medium 516, representing a computer storage disk, compact disk, etc.) comprising a computer readable media having control logic recorded thereon. The control~logic, when loaded into main memory 508 and executed by processor 506, enables the processor 506 to perform the operations described herein.
Although the OCCS controller 111 has been described with respect to an exemplary controller and processor, the OCCS controller 111 is not limited to this embodiment. The OCCS controller 111 controls the Pc~rms9sm~zo OCCSs. The OCCS controller 111 may be within an OCCS, such. as first OCCS 108 and/or second OCCS 112.
Alternatively, the O~CCS controller 111 could be within another component within the telecommunications network such as first LTE 106 and/or second LTE 114. The OCCS
controller 111 is any capability to control one or more OCCSs, such as first OCCS 108 and second OCCS 112.
While various embodiments of the present invention have been described above, it should be IO understood that they have been presented by way of example only, not limitation. Thus, the breadth and scope of the present invention should not be limited by any of the above-described exemplary embodiments, but should be defined only in accordance with the following claims and their equivalents.
LINE AND FACILITY FAILURES
The present invention relates generally to the reliability and restoration of optical transmission systems.
Telecommunications networks that carry telephone calls and. data include interconnected components that process calls and transfer data.
Optical transmission lines or links interconnect the components. Rather than having single optical transmission lines interconnecting call processing and data transfer components, the components may be interconnected by an optical network.
High speed data is modulated on light waves which are transmitted through the optical network. Any type of data can be carried over an optical link, including but not limited to speech, data input into or retrieved by a computer or computer database, and any digital data. Fiber optic cables carry far greater amounts of digital data than conventional electrical cables. A single fiber operating at approximately 10 Gigabits/second (Gb/s) and transmitting data according to a high-speed synchronous digital hierarchy standard, such as the SONET OC-192 protocol, carries a data equivalent to 129,024 voice calls.
Further bandwidth improvement can be achieved by modulating different electrical data signals on distinct light wave carriers having different frequencies. This technique is known as wavelength division.multiplexing (WDM). Optical systems using WDM
requixe optical transmitters and receivers that operate at different light wave frequencies. The optical transmission line, connecting an optical transmitter and receiver, can propagate many light wave signals of different frequencies simultaneously. For example, 16 OC-192 erbium~band~channels can be carried on a single S fiber pair with WDM.
Thus, fiber optic communications links, especially WDM communication links, carry vast amounts of information among distant sites to accomplish data, voice. and image connectivity over a large geographical area. Optical transmission lines, transmitters and receivers, however, can fail. The failure of such components can have a substantial economic and practical impact on network users and network service providers. Therefore, in designing communications networks, special measures are practiced to assure utmost reliability of network components and survivability in the~event of a failure.
Two types of failures experienced in a telecommunications network are line failures and module failures. A channel in a telecommunications network has a transmitter and a receiver, which are also referred to as modules, and a line between the transmitter and receiver. Line failures impair the optical communications line between two sites. Line failures include 'damage to the physical fiber and optical component failure, such as the malfunction of amplification equipment situated along the physical path of the fiber, optic cable. Line failures impair the communications line between two network sites. In contrast, a failure of the transmit or receive equipment housed at either end of an optical communications link is referred to as a module failure.
Both line failures and module failures disable the channel.
In the event of either a line or module failure,,restoration techniques are used to restore the traffic temporarily until the failure is repaired. The restoration approach varies depending on the failure.
Traffic may be restored using line protect switching (LPS)~or network restorative switching (NRS). If the traffic is restored using LPS, light termination equipment (LTE) switches the signal from the failed channel to a spare.channel within the LTE. If the traffic is restoxed using NRS, traffic is rerouted by switching the traffic to different routes either manually, based on information stored in switch tables or a pre-planned algorithm stored in the switch.
LPS ensures resiliency to fiber cuts by employing a spare channel, referred to as the protect channel, that normally does not carry traffic but may be used as a back-up should a channel in use fail. The protect channel is on a different path in order to reduce the likelihood that the protect channel will experience the same failure as the channel in use.
Creating and maintaining idle spare capacity is costly.
In order to reduce costs, one spare channel is available for restoration of multiple traffic carrying channels. When one protect channel is available to restore multiple traffic carrying channels, LPS cannot restore a failure of more than one traffic carrying channel. LPS is primarily aimed at restoring single channel failures and is implemented within LTE which is the local equipment that terminates the fiber optic cable. Since LPS is localized and simple, it is also very fast requiring 'only tens of milliseconds for restoring a failed communications link.
Because telecommunications networks include high capacity optical cables such as WDM, the networks are susceptible t.o failures that disable a very large number o~ channels and which cannot be restored by LPS
alone causing potential high volumes of traffic loss and significant economic impact. Accordingly, NRS is used to restore optical networks. Exchanges have the capability to reroute traffic automatically using switch table's or an algorithm to other transmission paths in the network. Exchanges which have switching capability are connected to LTE at each site and to other transmission paths in the network. When a fiber cut or other major fiber failure occurs disabling a span including a large number of telecommunications links between two switching nodes, NRS is employed by the exchange to reroute the traffic through the restoration network to circumvent the failure until repairs 'are completed.
Line protect switching (LPS) and network restorative switching (NRS) have separate but complementary roles in a modem network design. The LPS
can quickly restore simple localized failures without having to invoke the more complex NRS. In many applications, the LPS can switch traffic without causing any significant interruption to traffic. The NRS can handle network problems of a larger scope.
However, current LPS techniques do not allow for the restoration of failures that involve more than one channel. Although current LPS reroutes the traffic to a spare protect channel, only one protect channel is available to restore multiple channels. Therefore, if the protect channel is in use restoring a failure, subsequent failures cannot be restored using LPS.
In addition, current NRS does not allow for restoration by components in the optical network via a restoration network. NRS is currently employed by exchanges commonly used to provide access to the telecommunications network and switch calls to an appropriate destination rather than by components in the optical network. As a result, switching to an alternate path is, limited to exchange locations which are often housed proximate to areas of access to other telecommunications networks and private customers' termination equipment rather than near transmission path cross connect sites within the optical network.
In addition, NRS reroutes traffic to other traffic carrying channels. If traffic volumes are high, as they may be during certain hours of the day and certain days of the year, the network may have insufficient capacity~to handle both the traffic that was allocated for the traffic carrying channels and the restoration traf f is .
In the present invention, light termination equipment (LTE) sends an alarm to an optical cross connect switch (OCCS) controller to restore a failure when a protect channel is in use. The OCCS controller controls multiple optical cross connect switches (OCCSs) and addresses alarms by determining whether they can be restored. An OCCS is an optical switching device that interconnects numerous optical transmission lines to an optical restoration network. An optical restoration network .includes complete restorative spans of telecommunications links connected by the OCCSs.
The system of the present invention includes LTE, an OCCS, and an OCCS controller that are capable of restoring a second failure within one telecommunications cable. The LTE of the present invention can reroute optical and electrical signals to compensate for a failed component such as an optical transmitter, receiver, or transmission line. The present invention includes a protect, or spare, optical transmission line with which to replace a corresponding failed channel. The LTE can switch to the protect channel.when a channel fails due to either line or module failure. The LTE of the present invention is also capable of determining the facility type of channel failures and.sending an alarm to the OCCS to reroute failure of a line via the optical restoration network~if one o~ the two failures is a line failure.
The OCCS of the present invention can reroute optical and electrical signals to compensate for a channel that experiences line failure. However, the OCCS~cannot restore a channel that experiences module failure. As a result, when two coincident failures, a line and facility failure, occur the present invention restores the line failure via the first OCCS switching and restores the.module failure using the protect channel.
The OCCS controller of the present invention is capable of receiving the alarm from the LTE
notifying of a failure and sending a request to the OCCS to .restore a failed line through the optical restoration network.
. The method of restoring coincident line and facility failures is employed when a subsequent failure is detected. The subsequent failure is analyzed to determine the facility type of the failure. If the subsequent failure~is due to a line failure, an alarm is sent to the OCCS and the subsequent failure is restored~via the optical restoration network. If the subsequent failure is due to a module failure, the facility type of the previous failure is determined.
If the facility type of the previous failure is failure of a line, an alarm is sent to the OCCS and the previous failure is restored via the optical restoration network. If the facility type of the previous failure is also failure of a module, an alarm is sent to thevnetwork management center indicating that a' non-restorable failure has occurred.
. Further features and advantages of the invention, as well as the structure and operation of PC'f/US98/27~20 various embodiments~of the invention, are described in detail below with reference to the accompanying drawings.
The present invention is described with reference to the accompanying drawings, wherein:
Figure 1 is a block diagram of an optical restoration environment according to one embodiment of the.present invention;
. Figure 2 is a block diagram of an optical cross connect according to one embodiment of the present invention;
Figure 3 is a flowchart of the operation of the optical cross connect according to one embodiment of the present invention;
Figure 4A~is a block diagram of the optical cross.. connect illustrating the use of a protect channel to restore a single line failure according to one embodiment of the present invention;
Figure 4B is a block diagram of the optical cross connect illustrating the response to a first and second line failure according to one embodiment of the present invention;
Figure 4C is a block diagram of the optical cross connect illustrating the response to a second module failure and first line failure according to one embodiment of the~present invention; and Figure 5 is a block diagram of an optical cross connect switch.controller according to one embodiment of the present invention.
In the drawings, like reference numbers generally indicate identical, functionally similar, and/or structurally similar elements. The drawing in which~an element first appears is indicated by the leftmost digits) in the corresponding reference number.
The present invention provides a system and method of restoring subsequent failures within a telecbmmunications network. A system and method are provided. for sending an alarm from light termination equipment (LTE) to an optical cross connect switch (OCCS) controller. The OCCS controller addresses the alarm by determining whether to restore the failure by sending a command to an optical cross connect switch (OCCS). The OCCS controller can identify the facility type of the subsequent failure and retrieve the facility type of previous failures in order to ensure that a protect or spare channel is made available to IS restore a module failure in the event restoration of a module failure is needed.
The system and method of the present invention is illustrated as operating in an exemplary telecommunications network that carries digitized voice between two individuals speaking on telephones. The present invention is further illustrated within an exemplary optical cross connect network that is within the telecommunications network. However, the present invention is not limited to these environments and may be used in any network that requires restoration such as an X.25 network transmitting data.
Provided below is a brief description of the terminology used within this document. Additional description is provided in the following sections along with exemplary implementations and embodiments.
However, the present invention is not limited to the exemplary implementations and embodiments provided.
A "telecommunications network" is a network that carries information. The information may be digitized voice that is carried between two telephones or data that is carried between two computers. Several examples of telecommunications networks follow in the description of FIG. 1, however, a telecommunications network is not limited to these examples.
A telecommunications network may include termination equipment, optical cross connect switches, and optical cross connect switch controllers.
"Termination equipment" is equipment that terminates a cable within a telecommunications network and typically provides modulation and demodulation functionality.
Exemplary termination equipment is light termination equipment described further with respect to FIG. 1 and FIG. 2.
An "optical cross connect switch" provides switching functionality within an optical network. An optical network is a network within a telecommunications network that is comprised of transmission facilities that carry optical signals. An optical network may provide high speed transmission and be capable of carrying a significant amount of data.
"Optical cross connect switch controllers"
accept information from termination equipment and use the information to provide commands to optical cross connect switches. Optical cross connect switch controllers are processors with access to memory via a separate,or an associated memory storage device such as a hard drive, disk,. and/or standalone database.
However, an optical~cross connect switch controller is not limited to.these embodiments and may be any capability to control one or more optical cross connect switches. More detail is given about optical cross connect switch controllers below.
A "failure" is a component that experiences operational difficulties within the telecommunications network.' A disabling event causes the failure of one or more components vuithin the telecommunications network. If multiple failures occur, after the first failure. occurs, a later failure is referred to as a "subsequent failure" and the first failure or a previous failure is referred to as a "previous failure.."
Components within the telecommunications network can be~grouped into types of components, such as lines and modules. The failed component is a type of component which is the "failed facility type." A
previous failed component is also a type of component which is the "previous failed facility type." Two failed facility types and previous failed facility types are a "line failure" which is a failure of a line type component and a "module failure" which is a failure of a module or equipment type component.
FIG. 1 is a block diagram of an optical restoration environment 101 according to one embodiment of the present invention. Optical restoration environment 101 provides connectivity and switching capability for telecommunications services. An exemplary use for the optical restoration environment 101 is to restore channels in a network carrying a call placed by a caller on a first telephone 102 to a receiver~on a second telephone 120. However, optical restoration'environment 101 may be used to restore any voice or data traffic carried on a network.
Optical. restoration environment 101 includes a first telephone 102 used by a caller that is interconnected to a'second telephone 120 used by a receiver via a telecommunications network 122.
Telecommunications network 122 includes a first exchange,104, an optical cross connect 116, a second exchange 118, and an optical restoration network 110.
The first telephone 102 is connected to a first exchange 104 within the telecommunications network 122. The first exchange 104 provides switching functionality to connect to the appropriate telecommunications channel to establish service to the second telephone 120. The first exchange 104 is connected to optical cross connect 116 which is equipment that provides termination and optical switching for channels carried on an optical telecommunications 'cable 113. In addition, the optical cross connect 116 is connected to a second exchange 118 in order to establish connectivity via a channel link between the first telephone 102 and the second telephone 120. The second exchange 118 is connected to the second telephone 120 to provide switching and connectivity to second telephone 120.
According to the present invention, the optical~cross connect 116 is also connected to the optical restoration network 110 to provide restoration in the event of channel or cable failure. The optical cross. connect 116 includes a first light termination equipment (LTE) 106 and second LTE 114. The optical cross connect 116 also includes a first optical cross connect switch (OCCS) 108 and a second OCCS 112. The first exchange 104 is connected to the first LTE 106.
The first LTE 106 handles call termination, data rate conversion, and light protect switching (LPS) restoration functions. The first LTE 106 is connected to the first OCCS 108. The first OCCS 108 provides optical switching capability needed for network restoration switching (NRS) via the optical restoration network 110. The 'first OCCS 108 is connected to a second OCCS 112, for connectivity to the second telephone 120. The path between the first OCCS 108 and the second OCCS 112 is illustrative only. As would be apparent to~a person skilled in the art, additional intermediate optical cross-connect switches and filters can be added in a point-to-point circuit or any network topology~(eg. ring, mesh). In addition, the optical cross connect 116 includes an optical cross connect switch (OCCS) controller 111 which is connected to the first LTE 106,~the second LTE 114, the first OCCS 108, and the second OCCS 112 to provide control and allow for rerouting via the optical restoration network 110.
The first telephone 102 and second telephone 120 are used to place and receive calls via the telecommunications network 122. The first telephone 102 and second telephone 120 are exemplary and may be any equipment that can be used to initiate or receive a call.via a telecommunications network 122. Examples of other types of equipment that can be used to initiate and receive a call via the telecommunications network 122 are a wireless telephone, a pager, a personal computer and a modem.
The first exchange 104 and second exchange 118 are exemplary exchanges within the telecbmmunications network 122. The first exchange 204 and second exchange.118 provide switching capability to route a call via a telecommunications link that interconnects to the caller s destination. The first exchange 104 and second exchange 118 may be implemented PC"T/US98127720 using DMS-250 switches manufactured by Nortel.
The telecommunications network 122 may comprise many telecommunications networks including local exchange networks and interexchange networks.
Typically, equipment used to initiate and receive a call, such as.first telephone 102 and second telephone 120, is interconnected to an exchange within a local exchange network. Therefore, exemplary first exchange 102 and second exchange 118 are within~a local exchange network. A local exchange network comprises switches and termination equipment within a localized area. An example of a local exchange network is a local telephone operating company network such as Bell Atlantic. If the caller is calling long distance, the local exchange network will send the call to an interexchange switch in an interexchange network.
Similar to the local exchange network, an interexchange network comprises a plurality of switches, also referred to as exchanges, that are located throughout a geographic area. However, interexchange networks typically comprise of switches throughout a large geographic area to process long-distance telephone calls. For example, a national interexchange network comprises switches located throughout the nation. When a call is routed to the interexchange network, it may be routed to one or more switches within the interexchange network.
Optical cross connect equipment, such as exemplary optical.cross connect 116, is connected to the telecommunications cables within telecommunications network 122,.such.as exemplary telecommunications cable 113 between the first exchange 104 and second exchange 118. The optical cross connect 116 provides WO 99134540 PCTIUS98l27720 termination and switching functionality for signals carried bn optical telecommunication cable 113.
The optical cross connect 116 includes a first LTE 106 and a second LTE 114. The first LTE 106 S and second LTE 114 terminate the telecommunications cable 113. The first LTE 106 and second LTE 114 will be described in further detail with respect to FIG. 2.
The optical cross connect 116 includes a first,OCCS 108 and a second OCCS 112. The first OCCS
108 and second OCCS 112 can by any type of optical switch. For example, the first OCCS 108 and second OCCS~112 may be implemented using combinations of an integrated lithium niobate directional-coupler type switch. Other types of suitable optical switching technology include switches based on thermo-optic effect in polymer waveguides or silica glass, semiconductor amplification, piezo movement, and integrated indium phosphide. In addition, although a single first OCCS 108 and second OCCS 1I2 are shown for clarity', multiple discrete switches and couplers can be used to perform equivalent multiple-port optical switching.
The OCCS reroutes traffic based on an algorithm. An exemplary algorithm is the Real-Time Multiple. Wavelength Routing (RMWR) algorithm which uses collected data to~select an alternate path based on wavelength information stored in a centralized database'. An additional description of an algorithm used for rerouting traffic is described in U.S. Patent No. 4,956,835 entitled, "Method and Apparatus for Self-Restoririg and Self-Pxovisioning Communication Networks"
filed by Grover.
The first OCCS 108 and second OCCS 112 are connected to a telecommunications cable 113. The telecommunications cable 113 includes bidirectional optical fibers, line repeaters, and/or amplifiers.
Alternatively, the telecommunications cable 113 may include long-haul., single mode fiber. The telecommunications cable 113 is not linked to these components and may be any transmission medium cable of carrying signals in a telecommunications network.
The optical restoration network 110 is connected to the~first OCCS 108 and the second OCCS
112. The optical restoration network 110 comprises spare optical termination and cross connect equipment for restoration of traffic if the optical cross connect 116 in use fails. The optical restoration network 110 includes a plurality of spare components including LTEs, such as the. first LTE 106 and the second LTE 114, OCCSs, such as the first OCCS 108 and second OCCS 112, and telecommunications cables, such as telecommunications cable 113.
' The OCCS controller 114 is connected to the first LTE 106, the 'second LTE 114, the first OCCS 108, and the second OCCS 112. The OCCS controller 121 can be connected to any number of LTE and OCCSs. The OCCS
controller 111 receives information from the first LTE
106 and the second LTE 114. If the information indicates that traffic must be rerouted, the OCCS
controller 111 sends commands to the first OCCS 108 to reroute electrical signals via the optical restoration network 110. The~OCCS controller 111 may be implemented using any processor or a plurality of distributed processors that are coordinated by a communication link not shown.
FIG. 2 is a block diagram of optical cross connect 116. Illustrated within the first LTE 106 and the second LTE 114 are the transmitters, 206A, 2068, 206C, .. 206n, and the receivers, 210A, 2108, 210C,...
210n. Each one of the transmitters 206 is connected to a corresponding one of the receivers 210 via one of multiple channels.214A, 2148, 214C, ... 214n within the telecommunications cable 113. Also within telecommunications~cable 113 is a protect channel 212.
The protect channel 212 is spare and is used for restoration if one,of the channels 214 in use fails.
The protect channel 212 is connected to a transmitter 204 within the first LTE 106 and a receiver 208 within the second LTE 114.
Although, both first LTE 106 and second LTE
IS 114 have-transmitters and receivers, transmitters 206 are shown only in the first LTE 106 and receivers 210 are shown only in~the second LTE 114 for clarity. The transmitters and receivers are typically in an array made up of pairs of transmitters and receivers. In FIG. 2, each of the:transmitters 206 would actually be a transmit and receive pair.
Each.of the transmitters 206 transmit a signal carrying a digitized voice of a caller or any other data that was sent by equipment that originated a call, which is. shown in FIG. 1 as exemplary first telephone 102. In one embodiment, the transmitters 206 are modulated lasers, such as directly modulated semiconductor laser diodes or externally modulated lasers. Each one of the transmitters 206 is connected to one of the multiple channels 214 within the telecommunications cable 113. The transmitters 206 transmit signals via the channels 214 within the telecommunications cable 113 to the receivers 210.
WO 99!34540 PCTNS981Z7720 Similar to the transmitters 206, each one of the receivers 220 is connected to one of the multiple channels 214 within telecommunications cable 113 to receive.signals from the corresponding one of the transmitters 206. The receivers 210 demodulate electrical signals from the light wave signal of the corresponding carrier frequency. Receivers 210 can be optical detectors or any equipment that can receive and transduce the transmitted signal.
In one example, each one of the channels 214 within telecommunications cable 113 is an optical channel within a fiber optic cable. The signals within an optical fiber are modulated using various frequencies which allow one fiber optic cable to carry a large number of channels. As mentioned above, this technique is referred to as wavelength division multiplexing (WDM). Further description of transmitters, receivers, and fiber optic cables is given by Daniel Minoli in chapter 7 of his book entitled, "Telecommunications Technology Handbook,"
Artech House, Inc. (1991).
Each of~the channels 214 (also referred to as traffic carrying channels) carry normal non-restoration traffic within the telecommunications cable 123. The protect channel 212 is an optical channel within a fiber optic cable that is achieved by modulating a signal. at a particular frequency. Also, the transmitter 204 that transmits via the protect channel 212 is a modulated laser like the transmitters 206 on the other channels 214. The transmitter 204 may be implemented using the same technologies as the transmitters 206 on the other channels 214 within the telecommunications cable 113. Like the receivers 210 that receive signals from the traffic carrying channels 214, the receiver 208 on the protect channel 212 demodulates the received signal. The receiver 208 may be implemented with the same technologies as the receivers 210 that receive signals from the other channels 214.
Both the first LTE 106 and the second LTE 114 have processors referred to as the first LTE processor 216_and the second LTE processor 228, respectively.
l0 The first LTE processor 216 is connected to each of the transmitters 206 to obtain information about whether each of the transmitters 206 is in use and whether the transmitters 206 are experiencing operational difficulties. Similarly, the second LTE processor 218 is connected to each of the receivers 210 to obtain information about whether each of the receivers 210 is in use and whether the receivers 210 are experiencing operational difficulties. The first LTE processor 216 and the second LTE processor 218 are connected to the protect channel transmitter 204 and protect channel receiver 208,, respectively to obtain information about whether the protect channel 212 is in use and whether the protect channel is experiencing any operational difficulties. The first LTE processor 216 and second LTE processor 218 are any processor that can obtain information from and coordinate among the components with a first LTE 106 or second LTE 114.
FIG. 3 illustrates a restoration process 301 according to the present invention. FIG. 3 will be described with reference to the example of FIGS. 4A, 4B,~and 4C which illustrate various failures of channels 214 within telecommunications cable 113.
In step 304, either the first LTE 106 or the second LTE 114 detects a failure 404 in channel 214A.
The first LTE 106 may detect a failed transmitted 206.
A single optical detector at the second LTE 114 can detect a failure and send a fault signal to the second LTE processor 210 within the second LTE 114. Failure 404 may be detected electrically at first LTE 106 using conventional loss o~f signal techniques. Alternatively, failures may be detected by multiple optical detectors (not shown) along the channels 214. If an optical detector~detects a failure on one of the channels 214, the optical detector will send a fault signal to the first LTE 106.. Various methods of optical failure detection including optical and electrical detection techniques can be used.
In step 306, either the first LTE 106 or the second LTE 114, whichever detected the failure, determines whether the protect channel 212 is in use.
A determination of whether the protect channel 212 is in use is made to'evaluate whether the protect channel 212 'is available to restore the detected failure. FIG.
4A illustrates a single line failure in which the protect channel is available to restore the detected failure 404. If the protect channel 212 is not in use, the protect channel 212 is available to restore the detected failure 404 and the first LTE 106 proceeds to step 308. If the protect channel 212 is in use, the first LTE 106 proceeds to step 309 and sends an alarm to the OCCS controller 111.
In step 308, traffic is restored by the first LTE 106 on the protect channel 212. FIG. 4A
illustrates using the protect channel 212 to circumvent the single line failure 404. The incoming line to the first channel 214A is interconnected to the protect channel transmitter 204 rather than the first channel transmitter 206A: The protect channel 212 provides connectivity that~circumvents the failed channel 214A.
The protect channel receiver 208 within the second LTE
114 receives tl~e signal and sends the signal to the next component that will receive the signal and provide connectivity to the final destination, for example the second exchange 118 as shown in FIG. 1.
FIGS. 4B_and 4C illustrate multiple failures within telecommunications cable 113. If the protect channel 212 is in use, step 309 is performed to restore the detected failure. In step 309, the first LTE 106 or second LTE 114, whichever detected failure 404, sends an alarm to the OCCS controller 111. The information is,sent by ffirst LTE processor 216 or the second LTE processor 218. The first LTE processor 216 obtains the information from one of the transmitters 206. The second LTE processor 218 obtains the information from one of the receivers 210. The first LTE processor 216 and the second LTE processor 218 send the OCCS controller 111 information including whether the failure is a line failure or a module failure.
A failure on a channel 224 may be either a line failure or a module failure. A line failure is a failure of the channel 214 between the transmitter 206 and the receiver 210. FiG. 4B illustrates a first line failure 404 and a second line failure 406.
Transmitters 206 and receivers 210 are also referred to as modules. A module failure is a failure of either a transmitter 206 or a receiver 210. FIG. 4C illustrates a first line failure 404 and a second module failure 420.
The first LTE processor 216 can determine if the transmitters 206 (or associated receivers or modules not shown but collocated with each of the transmitters 206 iaithin the first LTE 106) fail. The second LTE processor 218 can determine if the receivers 210 (or associated transmitters or modules not shown but collocated with each of the receivers 210 within the second LTE 114) .fail. If a transmitter, receiver, or other module fails, a module failure, also referred to as an equipment failure has occurred. Both the i0 first LTE processor 216 and the second LTE processor 218 can report to~the OCCS controller 111 that a module failure occurred. If a line failure occurs, the photodetector within the one of the receivers 210 that corresponds to the failed channel will detect a loss of light and the second LTE processor 218 can determine that a line failure occurred and report that a line failure occurred to .the OCCS controller 111.
If a line failure occurs, two alarms may be sent to the OCCS controller 111. A photodiode within the second LTE 114 may detect a failure by detecting a loss of light and a receiver associated with transmitter 206 may detect a loss of communication with the second LTE 124.. If both the first~LTE 106 and the second LTE 114 send alarms for the same failure, the OCCS controller 211 can coordinate the alarms and determine that one failure occurred.
In step 310, the OCCS controller 111 identifies the type of the new failure using the information received from the first LTE 106 and/or the second LTE 114. The type of failure, either line or module, is determined in order to determine how to restore the failure.. According to the present invention, line failures, such as first line failure 404 and second line~failure 406, are restored either on the protect channel 212 or via the optical restoration network 110. The~first LTE 106 restores a single module failure 410 on a protect channel 212 as described earlier with respect to steps 306 and 308.
If multiple failures occur and the protect channel 212 capacity is insufficient to restore all of the failures, in step 310 the type of failure is determined in order to ensure that if the multiple failures include a module failure 410 and line failures, such as first line failure 404 and second line failure 406, the module failure.is restored on the protect channel 212 and the line failures are restored on the optical restoration network 110.
If .the type of new failure is a line failure, the OCCS controller 111 proceeds to step 312 to provide restoration through OCCS restoration actions using the optical restoration network 110. If the type of new failure is a module failure, the OCCS controller 111 proceeds to step 314 to obtain additional information in order to determine how to restore the failure.
In step .312, the OCCS controller 111 sends a command to the first OCCS 108 to restore the new failure.. If the new failure is a second line failure 406 as illustrated in FIG. 4B, then the second line failure 406 can be restored on the optical restoration network 110. Determining the facility type and rerouting the previous failure 404 are unnecessary because the second line failure 406 can be restored without affecting the previous failure 404.
The second.line failure 406 is restored by the OCCS controller 111 sending an alarm to the first OCCS 108. When the first OCCS 108 receives the alarm, the first OCCS 108 switches to reroute the optical electrical signals that were to be carried on the failed channel 214C via the optical restoration network 110.~~The optical electrical signals take a path from S the transmitter 206C within the first LTE 106 through the first OCCS 108 through a path 408 in optical restoration network. 110 to the second OCCS 114 which is connected to the receiver 210C within the second LTE
114 that receives the signal. When the second line failure 406 is repaired, the first OCCS 108 will reroute the electrical signals back to channel 214C.
In step 314, the OCCS controller 111 retrieves the type of previous failure. The OCCS
controller 111 retrieves the information from the first LTE processor 216 or the second LTE processor 218 that indicates whether the previous failure was a line failure or a module failure. The type of the previous failure indicates the type of failure that is being restored using the protect channel. As mentioned previously, although line failures, such as first~line failure 404 and second line failure 406 typically can be restored on a protect channel 212 or via an optical restoration netiwork 110, a single module failure 410 often can only be restored on a protect channel 212.
Therefore, if the new failure is a module failure 410 as was determined in step 312 and is illustrated in FIG. 4C, then determining the type of the previous failure 404 indicates whether the restoration in use for the previous failure 404 can be modified to accommodate the new. failure 410.
If the type of previous failure is a line failure as is illustrated in FIG. 4C, then the OCCS
controller 111 proceeds to step 318 to restore both the previous failure 404 and the new failure 410. If the type of previous failure is a module failure which is not shoc~n, then OCCS controller 111 proceeds to step 316 to send an alarm because neither the OCCS
controller 111 or~the first OCCS 108 can restore both the previous failure and the new failure.
In step 316, the OCCS controller 111 sends an alarm to a national network management center (NNMC) or other centralized or regional fault reporting center to report an unrestorable failure. If the new failure is a module.failure, such as module failure 410 shown in FIG. 4C, and the previous failure is a module failure then two module failures have occurred but only one protect channel 212 is available for restoration.
Assuming one protect channel is available and no other restoration technique can be used to in order to enable the optical cross connect 116 to restore the second module failure, the OCCS controller 121 sends an alarm to a fault reporting~center such as the NNMC to report an unrestorable failure.
The NNMC has staff and computer systems to detect and restore failures that cannot be restored with the automated systems in the telecommunications network 122. Computer systems in the NNMC may provide restoration automatically by rerouting traffic using switching tables ~ntithin exchanges, such as first exchange 104 and second exchange 118. If automated computer systems do not automatically provide reroutes, they may provide information to staff that manually implements changes to the software to reroute traffic.
For example, if multiple faults occur on telecommunications cable 113 that cannot be restored, either~computer systems or staff may modify the switch WO 99!34540 PCTNS98/Z7720 tables in first exchange 104 to send the traffic via different communications links until telecommunications cable 113 is repaired. However, if the failure is limited to one second module failure, the NNMC may do nothing or simply block traffic from attempting to use the channel 214C that cannot be restored until the channel 214C is repaired. Often all channels 214 within a telecommunications cable 113 are not in use so new calls can use the remaining channels 214A, 2148, ... 214n.
In step 318, the OCCS controller 111 sends a command~to the first OCCS 108 to reroute the previous line failure 404. After the previous line failure 404 has.been rerouted by the first OCCS 108, the OCCS
controller 111 sends a command to the first LTE 106 to switch the electrical signals that were carried on the second failed channel 214C to the protect channel 212 to restore the new module failure 410.
If the OCCS controller 111 performs step 318, then in step 310, the OCCS controller 111 identified that~~the new failure was a module failure 410, and in step 314, the OCCS controller 111 retrieved information indicating that the previous failure was a line failure 404. As mentioned previously, the scenario of a previous first line failure 404 and a new module failure 410 is illustrated in FIG. 4C. If the optical cross connect 416 cannot restore single module failures via .the optical restoration network 110, then the OCCS
controller 111 can only restore the new module failure 410 using the protect channel 212. As a result, restoration by the OCCS controller 111 of both the first line failure 404 and the module failure 410 is possible only if the first line failure is rerouted to the optical restoration network 110 by sending an alarm to the first OCCS 108.
The OCCS controller 111 sends a command to the first OCCS 108 to reroute the previous first line failure 404 via the optical restoration network 110.
The OCCS controller 111 may restore any number of line failures'by sending alarms to the first OCCS 108 which will reroute the electric signals via the optical restoration network. In other words, if channels 214A, 214B~, and 214D experience line failures prior to channel 214C experiencing a module failure, each line failure would have.been restored by the OCCS controller 111 performing earlier steps in the operation of optical termination and cross connect equipment 301 when~each failure wa.s experienced. The result would be that the first line failure would be restored on the protect channel 212 by the OCCS controller 1I1 performing steps 304, 306, and 308 and subsequent line failures would be restored via the optical restoration network 110 by the OCCS controller 111 performing steps 306, 309, 310, and 312. However, regardless of the number of line failures restored via the optical restoration network 110, when a module failure 410 is detected, if a line failure 404 is restored on the protect channel 212,.the line failure 404 is rerouted via the optical restoration network 110 to make the protect channel 212 available to restore the module failure 410. After the line failure 404 is restored by the first OCCS 108 via the optical restoration network, the first LTE 106 switches the electrical signals that were carried on channel 214C that experienced the module failure 410 to the protect channel 212.
The OCCS controller 111 of the present invention is preferably implemented using a computer system 502 as shown in block diagram form in FIG. 5.
The computer system 502 includes one or more processors, such as processor 506 connected to bus 504.
Also.cannected to bus 504 is main memory 508 (preferably random access memory, RAM) and secondary storage devices 510. The secondary storage devices 510 include, for example, a hard drive 512 and a removable storage medium drive 514 (such as a disk drive, for example) .
The functionality of the OCCS controller 111 is preferably performed by a computer program that resides in main memory 508 while executing. When executing, this computer program enables the computer system 502 to perform the features of the present invention as discussed herein. Thus, the OCCS controller 111 represents a controller of the computer system 502 (and of the processor 506). Alternatively, the functionality of the OCCS controller 111 is predominately or entirely performed by a hardware device, such as a hardware state machine.
. ~ In one embodiment, the present invention is a computer program product (such as removable storage medium 516, representing a computer storage disk, compact disk, etc.) comprising a computer readable media having control logic recorded thereon. The control~logic, when loaded into main memory 508 and executed by processor 506, enables the processor 506 to perform the operations described herein.
Although the OCCS controller 111 has been described with respect to an exemplary controller and processor, the OCCS controller 111 is not limited to this embodiment. The OCCS controller 111 controls the Pc~rms9sm~zo OCCSs. The OCCS controller 111 may be within an OCCS, such. as first OCCS 108 and/or second OCCS 112.
Alternatively, the O~CCS controller 111 could be within another component within the telecommunications network such as first LTE 106 and/or second LTE 114. The OCCS
controller 111 is any capability to control one or more OCCSs, such as first OCCS 108 and second OCCS 112.
While various embodiments of the present invention have been described above, it should be IO understood that they have been presented by way of example only, not limitation. Thus, the breadth and scope of the present invention should not be limited by any of the above-described exemplary embodiments, but should be defined only in accordance with the following claims and their equivalents.
Claims (16)
1. A method of addressing a subsequent failure in a telecommunications network that has experienced one or more previous failures, comprising the steps of:
(a) detecting the subsequent failure;
(b) identifying a failed facility type that caused the subsequent failure;
(c) determining whether a protect channel is restoring one of the one or more previous failures; and (d) when it is determined in step (c) that said protect channel is restoring one of the one or more previous failures, sending a notification of the subsequent failure to an optical cross connect switch controller;
wherein said notification includes said failed facility type that caused the subsequent failure.
(a) detecting the subsequent failure;
(b) identifying a failed facility type that caused the subsequent failure;
(c) determining whether a protect channel is restoring one of the one or more previous failures; and (d) when it is determined in step (c) that said protect channel is restoring one of the one or more previous failures, sending a notification of the subsequent failure to an optical cross connect switch controller;
wherein said notification includes said failed facility type that caused the subsequent failure.
2. A method of addressing a subsequent failure in a telecommunications network that has experienced one or more previous failures, comprising the steps of:
(a) receiving a notification of the subsequent failure, wherein said notification includes a failed facility type that caused the subsequent failure;
(b) determining whether the subsequent failure is restorable via an optical cross connect switch; and (c) addressing the subsequent failure.
(a) receiving a notification of the subsequent failure, wherein said notification includes a failed facility type that caused the subsequent failure;
(b) determining whether the subsequent failure is restorable via an optical cross connect switch; and (c) addressing the subsequent failure.
3. The method of claim 2, wherein step (b) comprises the steps of:
(i) determining whether said failed facility type received in said notification of the subsequent failure is a line failure; and (ii) if it is determined in step (i) that said failed facility type is said line failure, determining that the subsequent failure is restorable via said optical cross connect switch.
(i) determining whether said failed facility type received in said notification of the subsequent failure is a line failure; and (ii) if it is determined in step (i) that said failed facility type is said line failure, determining that the subsequent failure is restorable via said optical cross connect switch.
4. The method of claim 2, wherein step (b) comprises the steps of:
(i) determining whether said failed facility type received in said notification of the subsequent failure is a module failure;
(ii) if it is determined in step (i) that said facility type is said module failure, determining a previous failed facility type of one of the one or more previous failures that is restored on a protect channel; and (iii) if it is determined in step (ii) that said previous failed facility type is a line failure, determining that the subsequent failure is restorable via said protect channel.
(i) determining whether said failed facility type received in said notification of the subsequent failure is a module failure;
(ii) if it is determined in step (i) that said facility type is said module failure, determining a previous failed facility type of one of the one or more previous failures that is restored on a protect channel; and (iii) if it is determined in step (ii) that said previous failed facility type is a line failure, determining that the subsequent failure is restorable via said protect channel.
5. The method of claim 2, wherein step (b) comprises the steps of:
(i) determining whether said failed facility type received in said notification of the subsequent failure is a module failure;
(ii) if it is determined in step (i) that said facility type is said module failure, determining a previous failed facility type of one of the one or more previous failures that is restored on one of one or more protect channels;
(iii) if it is determined in step (ii) that said previous failed facility type is said module failure and additional previous failures are restored on additional protect channels, repeat step (ii) to determine another previous failed facility type for another one of the one or more previous failures that is restored via another one of the one or more protect channels; and (iv) if it is determined in step (iii) that said another previous failed facility type is a line failure, determining that the subsequent failure is restorable via said protect channel.
(i) determining whether said failed facility type received in said notification of the subsequent failure is a module failure;
(ii) if it is determined in step (i) that said facility type is said module failure, determining a previous failed facility type of one of the one or more previous failures that is restored on one of one or more protect channels;
(iii) if it is determined in step (ii) that said previous failed facility type is said module failure and additional previous failures are restored on additional protect channels, repeat step (ii) to determine another previous failed facility type for another one of the one or more previous failures that is restored via another one of the one or more protect channels; and (iv) if it is determined in step (iii) that said another previous failed facility type is a line failure, determining that the subsequent failure is restorable via said protect channel.
6. The method of claim 2, wherein step (b) comprises the steps of:
(i) determining whether said failed facility type received in said notification of the subsequent failure is a module failure;
(ii) if it is determined in step (i) that said facility type is said module failure, determining a previous failed facility type of one of the one or more previous failures that is restored on a protect channel;
(iii)if it is determined in step (ii) that said previous failed facility type is a module failure, determining that the subsequent failure is not restorable.
(i) determining whether said failed facility type received in said notification of the subsequent failure is a module failure;
(ii) if it is determined in step (i) that said facility type is said module failure, determining a previous failed facility type of one of the one or more previous failures that is restored on a protect channel;
(iii)if it is determined in step (ii) that said previous failed facility type is a module failure, determining that the subsequent failure is not restorable.
7. The method of claim 2, wherein step (b) comprises the steps of:
(i) determining whether said failed facility type received in said notification of the subsequent failure is a module failure;
(ii) if it is determined in step (i) that said facility type is said module failure, determining a previous failed facility type of one of the one or more previous failures that is restored on one of one or more protect channels;
(iii) if it is determined in step (ii) that said previous failed facility type is said module failure and additional previous failures are restored on additional protect channels, repeat step (ii) to determine another previous failed facility type for another one of the one or more previous failures that is restored via another one of the one or more protect channels; and (iv) if it is determined in step (iii) that said another previous failed facility type is said module failure, determining that the subsequent failure is not restorable.
(i) determining whether said failed facility type received in said notification of the subsequent failure is a module failure;
(ii) if it is determined in step (i) that said facility type is said module failure, determining a previous failed facility type of one of the one or more previous failures that is restored on one of one or more protect channels;
(iii) if it is determined in step (ii) that said previous failed facility type is said module failure and additional previous failures are restored on additional protect channels, repeat step (ii) to determine another previous failed facility type for another one of the one or more previous failures that is restored via another one of the one or more protect channels; and (iv) if it is determined in step (iii) that said another previous failed facility type is said module failure, determining that the subsequent failure is not restorable.
8. The method of claim 2, wherein step (c) comprises the step of restoring the subsequent failure via said optical cross connect switch.
9. The method of claim 2, wherein step (c) comprises the steps of:
restoring one of the one or more previous failures that was restored on a protect channel via said optical cross connect switch; and restoring the subsequent failure via said protect channel.
restoring one of the one or more previous failures that was restored on a protect channel via said optical cross connect switch; and restoring the subsequent failure via said protect channel.
10. The method of claim 2, wherein step (c) comprises the step of:
sending an alarm to a centralized network management center.
sending an alarm to a centralized network management center.
11. An apparatus, comprising:
equipment for terminating a telecommunications span;
identifying means for identifying a failed facility type of a subsequent failure;
determining means for determining whether a protect channel is restoring a previous failure; and notification means for notifying an optical cross connect switch controller of said subsequent failure.
equipment for terminating a telecommunications span;
identifying means for identifying a failed facility type of a subsequent failure;
determining means for determining whether a protect channel is restoring a previous failure; and notification means for notifying an optical cross connect switch controller of said subsequent failure.
12. An optical cross connect switch controller, comprising:
a processor;
receiving notification means for enabling said processor to receive a notification of a subsequent failure, wherein said notification includes a failed facility type that caused said subsequent failure;
restoration determining means for enabling said processor to determine whether said subsequent failure is restorable via an optical cross connect switch; and restoration command means for enabling said processor to send a command to restore said subsequent failure via said optical cross connect switch.
a processor;
receiving notification means for enabling said processor to receive a notification of a subsequent failure, wherein said notification includes a failed facility type that caused said subsequent failure;
restoration determining means for enabling said processor to determine whether said subsequent failure is restorable via an optical cross connect switch; and restoration command means for enabling said processor to send a command to restore said subsequent failure via said optical cross connect switch.
13. The optical cross connect switch controller of claim 12, wherein said restoration determining means comprises:
failed facility type determining means for determining said failed facility type; and restoration determining means for determining whether said subsequent failure is restorable using said failed facility type.
failed facility type determining means for determining said failed facility type; and restoration determining means for determining whether said subsequent failure is restorable using said failed facility type.
14. The optical cross connect switch controller of claim 12, wherein said restoration determining means comprises:
failed facility type determining means for determining said failed facility type;
restoration determining means for determining whether said subsequent failure is restorable using said failed facility type;
previous failed facility type determining means for determining a previous failed facility type; and restoration determining means for determining whether said subsequent failure is restorable using said previous failed facility type.
failed facility type determining means for determining said failed facility type;
restoration determining means for determining whether said subsequent failure is restorable using said failed facility type;
previous failed facility type determining means for determining a previous failed facility type; and restoration determining means for determining whether said subsequent failure is restorable using said previous failed facility type.
15. The optical cross connect switch controller of claim 12, wherein said restoration command means comprises:
restoration means for restoring said subsequent failure via said optical cross connect switch.
restoration means for restoring said subsequent failure via said optical cross connect switch.
16. The optical cross connect switch controller of claim 12, wherein said restoration command means comprises:
previous failure restoration means for restoring one of one or more previous failures that was restored on a protect channel via said optical cross connect switch; and subsequent failure restoration means for restoring said subsequent failure via said protect channel.
previous failure restoration means for restoring one of one or more previous failures that was restored on a protect channel via said optical cross connect switch; and subsequent failure restoration means for restoring said subsequent failure via said protect channel.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US09/001,884 US6233072B1 (en) | 1997-12-31 | 1997-12-31 | Method and system for restoring coincident line and facility failures |
| US09/001,884 | 1997-12-31 | ||
| PCT/US1998/027720 WO1999034540A1 (en) | 1997-12-31 | 1998-12-30 | Method and system for restoring coincident line and facility failures |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2316856A1 true CA2316856A1 (en) | 1999-07-08 |
Family
ID=21698274
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002316856A Abandoned CA2316856A1 (en) | 1997-12-31 | 1998-12-30 | Method and system for restoring coincident line and facility failures |
Country Status (5)
| Country | Link |
|---|---|
| US (2) | US6233072B1 (en) |
| EP (1) | EP1050122A4 (en) |
| JP (1) | JP2002500468A (en) |
| CA (1) | CA2316856A1 (en) |
| WO (1) | WO1999034540A1 (en) |
Families Citing this family (25)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6233072B1 (en) * | 1997-12-31 | 2001-05-15 | Mci Communications Corporation | Method and system for restoring coincident line and facility failures |
| US6263242B1 (en) | 1999-03-25 | 2001-07-17 | Impulse Dynamics N.V. | Apparatus and method for timing the delivery of non-excitatory ETC signals to a heart |
| US6992978B1 (en) | 1999-06-02 | 2006-01-31 | Alcatel Communications, Inc. | Method and system for path protection in a communications network |
| US6223072B1 (en) | 1999-06-08 | 2001-04-24 | Impulse Dynamics N.V. | Apparatus and method for collecting data useful for determining the parameters of an alert window for timing delivery of ETC signals to a heart under varying cardiac conditions |
| US20010038471A1 (en) * | 2000-03-03 | 2001-11-08 | Niraj Agrawal | Fault communication for network distributed restoration |
| US6763190B2 (en) * | 2000-03-03 | 2004-07-13 | Lucent Technologies Inc. | Network auto-provisioning and distributed restoration |
| US20020021466A1 (en) * | 2000-06-29 | 2002-02-21 | Peter Abrams | Shortest path first restoration routing in a fiberoptic network |
| US6684100B1 (en) * | 2000-10-31 | 2004-01-27 | Cardiac Pacemakers, Inc. | Curvature based method for selecting features from an electrophysiologic signals for purpose of complex identification and classification |
| US6567576B2 (en) * | 2001-02-05 | 2003-05-20 | Jds Uniphase Inc. | Optical switch matrix with failure protection |
| US20020191247A1 (en) * | 2001-04-30 | 2002-12-19 | Xiang Lu | Fast restoration in optical mesh network |
| US6882766B1 (en) | 2001-06-06 | 2005-04-19 | Calient Networks, Inc. | Optical switch fabric with redundancy |
| EP1461890B1 (en) * | 2001-09-04 | 2008-12-17 | Rumi Sheryar Gonda | Method for supporting sdh/sonet aps on ethernet |
| JP2003298633A (en) * | 2002-04-05 | 2003-10-17 | Fujitsu Ltd | Transmission equipment having data channel fault informing function in the case of control channel fault |
| US6950702B2 (en) * | 2002-07-15 | 2005-09-27 | Cardiac Pacemakers, Inc. | Use of curvature based features for beat detection |
| US7031764B2 (en) * | 2002-11-08 | 2006-04-18 | Cardiac Pacemakers, Inc. | Cardiac rhythm management systems and methods using multiple morphology templates for discriminating between rhythms |
| DE60322096D1 (en) * | 2002-11-21 | 2008-08-21 | Huawei Tech Co Ltd | Method for signaling a connection error in a network |
| US7020814B2 (en) * | 2003-03-18 | 2006-03-28 | Cisco Technology, Inc. | Method and system for emulating a Fiber Channel link over a SONET/SDH path |
| US7792571B2 (en) | 2003-06-27 | 2010-09-07 | Cardiac Pacemakers, Inc. | Tachyarrhythmia detection and discrimination based on curvature parameters |
| US7251743B2 (en) * | 2003-11-20 | 2007-07-31 | International Business Machines Corporation | Method, system, and program for transmitting input/output requests from a primary controller to a secondary controller |
| US20060039697A1 (en) * | 2004-08-19 | 2006-02-23 | International Business Machines Corporation | Autonomous optical path management device |
| US7277747B2 (en) * | 2004-11-23 | 2007-10-02 | Cardiac Pacemakers, Inc. | Arrhythmia memory for tachyarrhythmia discrimination |
| US8036531B2 (en) | 2006-12-14 | 2011-10-11 | Verizon Patent And Licensing Inc. | Hybrid switch for optical networks |
| US8737228B2 (en) * | 2007-09-27 | 2014-05-27 | International Business Machines Corporation | Flow control management in a data center ethernet network over an extended distance |
| US8589198B2 (en) * | 2010-11-18 | 2013-11-19 | General Electric Company | Methods and systems involving power system grid management |
| CN108292952B (en) * | 2015-11-26 | 2021-07-06 | 日本电信电话株式会社 | Communication system and failure detection method |
Family Cites Families (21)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CA1291549C (en) * | 1987-11-06 | 1991-10-29 | Wayne D. Grover | Method and apparatus for self-healing and self-provisioning networks |
| BE1004668A3 (en) * | 1991-04-02 | 1993-01-05 | Bell Telephone Mfg | PROTECTION DEVICE FOR AN OPTICAL transmitter / receiver device. |
| US5218465A (en) * | 1991-09-03 | 1993-06-08 | Motorola, Inc. | Intelligent interconnects for broadband optical networking |
| US5345446A (en) * | 1992-11-06 | 1994-09-06 | At&T Bell Laboratories | Establishing telecommunications call paths in broadband communication networks |
| JPH07226736A (en) * | 1994-02-14 | 1995-08-22 | Hitachi Ltd | Fault recovery method in mesh network |
| US5715074A (en) * | 1995-04-14 | 1998-02-03 | Netsu; Yutaka | Duplex switching apparatus |
| JPH11508427A (en) * | 1995-06-26 | 1999-07-21 | テレフオンアクチーボラゲツト エル エム エリクソン（パブル） | Self-healing net |
| JP2617701B2 (en) * | 1995-06-28 | 1997-06-04 | 宮城日本電気株式会社 | How to avoid misconnection when switching VT paths |
| CA2164071C (en) * | 1995-09-06 | 2001-08-21 | Thomas P. J. Flanagan | Optical communication system |
| US5777761A (en) * | 1995-12-22 | 1998-07-07 | Mci Communications Corporation | System and method for photonic facility and line protection switching using wavelength translation |
| US6005694A (en) * | 1995-12-28 | 1999-12-21 | Mci Worldcom, Inc. | Method and system for detecting optical faults within the optical domain of a fiber communication network |
| US6108113A (en) * | 1995-12-29 | 2000-08-22 | Mci Communications Corporation | Method and system for transporting ancillary network data |
| US5884017A (en) * | 1995-12-29 | 1999-03-16 | Mci Communications Corporation | Method and system for optical restoration tributary switching in a fiber network |
| US5914798A (en) * | 1995-12-29 | 1999-06-22 | Mci Communications Corporation | Restoration systems for an optical telecommunications network |
| US6144633A (en) * | 1996-04-23 | 2000-11-07 | Hitachi, Ltd. | Self-healing network, method for transmission line switching thereof, and transmission equipment thereof |
| US5903370A (en) * | 1996-06-28 | 1999-05-11 | Mci Communications Corporation | System for an optical domain |
| US6078596A (en) * | 1997-06-26 | 2000-06-20 | Mci Communications Corporation | Method and system of SONET line trace |
| US6233072B1 (en) * | 1997-12-31 | 2001-05-15 | Mci Communications Corporation | Method and system for restoring coincident line and facility failures |
| US5870212A (en) * | 1998-01-14 | 1999-02-09 | Mciworldcom, Inc. | Self-healing optical network |
| US6111672A (en) * | 1998-02-20 | 2000-08-29 | Mci Communications Corporation | Method, apparatus, and computer program product for optical network restoration |
| US6038044A (en) * | 1998-02-20 | 2000-03-14 | Mci Communications Corporation | Ring/mesh optical network |
-
1997
- 1997-12-31 US US09/001,884 patent/US6233072B1/en not_active Expired - Fee Related
-
1998
- 1998-12-30 WO PCT/US1998/027720 patent/WO1999034540A1/en not_active Application Discontinuation
- 1998-12-30 JP JP2000527048A patent/JP2002500468A/en not_active Withdrawn
- 1998-12-30 CA CA002316856A patent/CA2316856A1/en not_active Abandoned
- 1998-12-30 EP EP98964979A patent/EP1050122A4/en not_active Withdrawn
-
2001
- 2001-03-12 US US09/804,365 patent/US20010043560A1/en not_active Abandoned
Also Published As
| Publication number | Publication date |
|---|---|
| EP1050122A4 (en) | 2002-10-02 |
| US6233072B1 (en) | 2001-05-15 |
| US20010043560A1 (en) | 2001-11-22 |
| EP1050122A1 (en) | 2000-11-08 |
| WO1999034540A1 (en) | 1999-07-08 |
| JP2002500468A (en) | 2002-01-08 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US6233072B1 (en) | Method and system for restoring coincident line and facility failures | |
| US7903544B2 (en) | Private network link verification procedure in free space optical communication network | |
| US6005694A (en) | Method and system for detecting optical faults within the optical domain of a fiber communication network | |
| US5914798A (en) | Restoration systems for an optical telecommunications network | |
| US6331905B1 (en) | Network switch failure restoration | |
| US6587235B1 (en) | Method and apparatus for capacity-efficient restoration in an optical communication system | |
| US6377374B1 (en) | Method apparatus and computer program product for optical network restoration | |
| US6108113A (en) | Method and system for transporting ancillary network data | |
| US6088141A (en) | Self-healing network | |
| US6370110B1 (en) | Back-up restoration technique for SONET/SHD rings | |
| US6078596A (en) | Method and system of SONET line trace | |
| JP2000503182A (en) | METHOD AND SYSTEM FOR OPTICAL RECOVERY END SWITCH CONNECTION IN FIBER NETWORK | |
| WO1997024901A9 (en) | Restoration systems for an optical telecommunications network | |
| US6798991B1 (en) | Optical communication systems, optical communication system terminal facilities, optical communication methods, and methods of communicating within an optical network | |
| Barnett et al. | The TPC-5 cable network | |
| US20030005095A1 (en) | Method and system for programmable submarine network configuration plans to enable diverse service level agreements in telecommunication networks | |
| US7054558B2 (en) | Method for traffic protection in WDM fiber optic transport networks | |
| MXPA00006556A (en) | Method and system for restoring coincident line and facility failures | |
| MXPA99008268A (en) | Technique for the restoration of backings of optical synchronic network rings / sincron digital hierarchy | |
| JPH05292107A (en) | Fault information transmission system and method for optical transmitter having ring network |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EEER | Examination request | ||
| FZDE | Discontinued | ||
| FZDE | Discontinued |
Effective date: 20051230 |