CA2015926A1 - Optical transmission apparatus - Google Patents
Optical transmission apparatusInfo
- Publication number
- CA2015926A1 CA2015926A1 CA002015926A CA2015926A CA2015926A1 CA 2015926 A1 CA2015926 A1 CA 2015926A1 CA 002015926 A CA002015926 A CA 002015926A CA 2015926 A CA2015926 A CA 2015926A CA 2015926 A1 CA2015926 A1 CA 2015926A1
- Authority
- CA
- Canada
- Prior art keywords
- optical
- electro
- standby
- switching means
- optic
- 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
- H04B—TRANSMISSION
- H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
- H04B10/03—Arrangements for fault recovery
- H04B10/032—Arrangements for fault recovery using working and protection systems
Abstract
ABSTRACT
Optical Transmission Apparatus The apparatus comprises at least one standby optical fibre transmission path and at least one worker optical fibre transmission path. Each end of the paths is terminated by an associated transmit and receive electro-optic converters. The converters are connected to respective electrical protection switching devices. At least one optical switching means interfaces the electro-optic converters with the optical fibres at one end of the transmission paths and is arranged to switch the optical transmission between worker and standby fibres when a fault is detected.
Optical Transmission Apparatus The apparatus comprises at least one standby optical fibre transmission path and at least one worker optical fibre transmission path. Each end of the paths is terminated by an associated transmit and receive electro-optic converters. The converters are connected to respective electrical protection switching devices. At least one optical switching means interfaces the electro-optic converters with the optical fibres at one end of the transmission paths and is arranged to switch the optical transmission between worker and standby fibres when a fault is detected.
Description
OPTICAL TRANSMISS~ON APPARATWS
The present invention relates to the protection and testing of optical transmission apparatus.
Currently the only method of providing protection on such optical transmission apparatus is by electrical switchingO In these circumstances the protection arrangement consists of electro-optic converters permanently connected to the protected optical fibre and preceded by electrical switches. This prior art ~ortn of protection is shown in Figure 1 which shows a standby system and a worker number 1 system through to a worker number N system. Each system comprises a transmit and receive optical fibre 1,2, interconnecting a respective electro-optic converter 3,4 comprising a transmitter and receiver. The electro-optic converters 3,4 are connected to electrical protection switches 5. Control logic lOb is provided, and a control bus 13 interconnects the control logic lOb with the electrical protection switches 5. An alarm bus 11, and an auxiliary channel 12 interconnect the control logic lOb and the electro-optlc converters 3, 4. The apparatus described in Figure 1 is only applicable on a point-to-point basis and is intolerant of most multiple ~aults, (e.g. the . : . - :. . -.
: ~ ' , '" ' ,': , " ~ ~
: ', :
simultaneous failure of a part of the standby system and a part of a worker system~. Under these circumstances restoration cannot be achieved although sufficient workiny equipment is available. Faults cannot be located below system electro-optic converter -fibre- opto-electronic converter level without manual intervantion.
An aim of the present invention is to provide an optical transmission apparatus having a protection and testing facility which overcomes the above mentioned problems in an efficient and economical manner.
According to the present invention there is provided an optical transmission apparatus comprising at least one standby optical fibre transmission path and at least one worker optical fibre transmission path, terminated at each end by associated transmit and receive electro-optic converters which are connected to respective electrical protection switching means having input and output lines, characterised in that, at least one optical switching means is arranged to interface the electro-optic converters at one end of the optical fibre transmission paths, with the optical fibres, and switch the optical transmission hetween the worker and standby fibres when a fault is detected, by the electro-optic converters, in a transmission path.
.
~''',-' "' ~: ', ' .
, .
- , . ~ .
Accord.ing to an aspect of the present invention, an optical switching means is provided at each end of the optical fibre transmission paths which interface the electro-optic converters at each end of the paths, with the optical fibres.
According to a further aspect of the present invention, the optical switching means is arranged to interface a plurality of worker paths and a plurality of associated standby paths with a plurality of worker electro-optic converters and a single standby electro-optic converter.
According to yet a further aspect of the present invention, the optical switching means is arranged to provide local or remote loopback connections for testing purposes.
This arrangement of optical transmission apparatus has the advantage of being more tolerant in respect of multiple faults. The standby optical transmitter and receiver at each end of the standby optical transmission path, and the standby optical fibres themselves, can be used independently to by-pass faults on up to six systems simultaneously.
. .
.
.
- :
:
- ~, ': .
The standby transmikters and receivers can be used to locate faults to subsystem level (e.g. transmitter, receiver or fibre) by using the optical switches to provide local, and the electrical switches to provide remote loopback testing facilities.
In point-to-multipoint situations l:N protection can be employed at a central node wh~re one to one protection would previously had been required. This results in considerable economies at the central node.
Exemplary embodiments of the present invention will now be described with reference to the accompanying drawings wherein:-Figure 1 shows an optical fibre transmission systemaccording to a prior art arrangement, Figure 2 shows an optical transmission system in accordance with one embodiment of the present invention, Figure 3 shows an alternative embodiment of the present invention which shows a point-to-multipoint optical transmission system, and : ' ' ': ,' . ' :. :
... . : .
.
.
- : .
,' ~' ' ~' ' . '. '~ .
F20707C~
Figure 4 shows a ~low chart o~ the actions taken by control logic when an alarm is received~
Referring to Figure 2, the equipment which is identical to that of the prior art arrangement of Figure bear the same reference numerals. In Figure 2 a plurality of transmission paths are shown, a standby path SB, a first worker path Wl and an N worker path WN. It will be appreciated that a plurality of paths are provided between systems Wl and WN. Each transmission path comprises two optical fibres 1,2 for transmission in opposed directions.
The optical fibre 1 of each system is connected to an electro-optic transmitter 3 at one end and an electro-optic receiver ~ at the opposite end. The optical ~ibre 2 is connected to an electro-optic transmitter 3 and, to an electro-optic receiver 4 at its opposite end. The transmitters and receivers at each end are connected to associated electrical protection switches EPS 5 via corresponding electrical links 6.
Typically, the electro optic transmitters 3 and receivers 4 are provided by System 565 manufactured by the Plessey Company Limited. The Plessey System 565 is an optical fibre digital system operating at 565 Mbits/s. It - ., ::
' .. ' : ' ,.: ., ~ -' . .
- : . , - - , , . :,, .
-: - , .
.
is combined muldex and bothway line terminal which can handle four independent plesiochronous and CMI (code mark inversion) encoded data channels to CCITT recommendations.
The electro-optic transmitter 3/receiver 4 are also provided with an auxiliary channel 12 providing a supervisory system.
The electrical protection switches 5, each provide route protection terminating equipment at each end of a transmission path to be protected. Such equipment is known in the art. The equipments at each end are linked via a data communications link providing the means for co-ordinating the switching and control activities of the two equipments. When a bit error rate is worse than a threshold value, a signal is transmitted to the equipment indicating the deterioration of transmission quality. This signal is used to determine whether to switch to a different transmission path or not. The switching is carried out by use of RF relays. Failure of any part of the electrical protection switches will normally result in traffic being maintained on the worker bearers.
Fach optical fibre path end is interfaced with the associated electro-optic converters 3,4 by an optical switch means 7. An example of such a switch means is discussed in an article entitled "Switching in the Optical Domain" P. J.
, ... . .
, . .
.' ~', ' ' ~' ' ' ~ ,' ': :
Duthie, Plessey Research and Technology, Research Review 1989. A fault in any optical fibre route is detected electrically by the standard alarm and fault monitoring circuits built into the electro-optic converters 3,4. Upon detection of the breakdown, the control logic 10 associated with the optical switchiny means 7 receives the alarm and fault conditions from the converters 3,4 and operates the optical switching means in order to select an alternative path in order to restore correct transmission. The fault detection is performed at both ends of the transmission system by virtue of the fact that an optical switching means 7 and control logic 10 is provided at each end of the route.
The optical switching means 7 is so designed that the standby transmission equipment can be connected to any of the worker fibres or any of the worker equipments. Any of the worker equipments can also be connected to the standby transmission fibres.
Each electro-optic converter (3) provides an input fail alarm indication (I/PFn) and an output fail alarm indication (TxFn). Each opto-electric converter (4) provides an input fail alarm indication (FFn) and an output fail alarm indication (0/PFn). Where "n" indicates the working system number. The standby system alarms are designated "s 1l .
.
. . , : .
:
'' ' . :. ' ~ :
~' ' F20707C~ $~
All the above information is ~ed to the local control logic (10) via the Alarm bus (11). The local control loyic, which is realised as an Intel 8086 or similar microprocessor, also receives and transmits in~ormation from/to the remote control logic via the auxiliary channel (12), built into the electro-optic/opto-electronic converters. The auxiliary channel is triplicated for security and a majority decision taken at the receiving end.
The control commands are despatched via the control bus 13 to the optical switch means 7 and el~ctrical protection switches 5. On receipt of an alarm the control logic initiates the restoration sequence designated cycle B in Figure 4. On restoration of service it reverts to the monitoring cycle A of Figure 4, until repairs are completed and the standby system restored to normal. For diagnostic purposes a test generator 9a and receiver 9b are connected to the out-of-service "standby" system and provision is made for manual local, (optical) and remote (electrical) loop back. The necessary commands being initiated via the control logic 10 and auxiliary channel 12.
Referring to Figure 4, a flow chart is shown of the actions taken by the control logic 10 (Figures 2,3) when an alarm is received. Under normal, no fault conditions, a '`' .' . ~ .' ' .
;
. : ~ .": , ' ' - ~ ~
F20707CA ~3~ 5 ~
g monitoring cycle A is perform~d. In step, S1 the local alarm bus is interrogated for an alarm. In step S2, if no alarm is found, the auxiliary channel is interroyated in step S3. If a switching operation is required in step S4, the requested optical switch is operated in step S5, and step Sl is repeated. If in step S4, no switching operation is required, a check is made to see if a request has been made for alarm information. If it has, step S7 is performed and the alarm information is provided, and then step Sl is repeated. If no information is requested, step S1 is repeated.
When an alarm is found in step S2, cycle B is entered which is a restoration cycle. In steps S8-S12, checks are made to identify various faults respectively, as follows, input fail alarm on standby bearer I/PFs, input fail on bearer numbered 1 to n, I/PFn, transmit fail alarm on standby bearer TxFs, a remote input fail alarm on standby bearer FFs, an output fail alarm on standby bearer, O/PFs.
Each of these steps are performed and if an alarm is detected, step S16 is performed to initiate a non-urgent alarm, and then step S3 is performed to interrogate the auxiliary channel. If no faults are found during steps S8-S12, step 13 is performed to detect a fail alarm on the transmit bearer numbered 1 to n. If a fault is detected, . - ' ~ ' , . ~
- ~ .
:' ' ~ 3~ 3~
F20707C~
step Sl7 causes operation of the appropriate electrical and optical switch to interchange the electro-optic converter N
with the standby electro-opti~ converters. Step S1~
confirms whether the transmit fault in bearer n has been removed. If it has, t~len step S16 initiates a non-urgent alarm and the process returns to step S3 to interrogate the auxiliary channel. If the fault is still present step S19 is performed to initiate an urgent alarm, and the process returns to step S3.
I~ no fault is detected at step S13, step S14 is performed to ascertain if a fail alarm has been detected on the remote bearers numbered 1 to n. If it has, then step S20 requests the status of the remote transmit alarm of bearer number n. Step S21 acknowledges the response. If no response is received step S19 is performed to initiate an urgent alarm, followed by step S3 to interrogate the auxiliary channel. If a response is received, step S22 determines whether a electro-optic fault on remote bearer n is present. If it is, step S3 is performed. If no fault is present, step S23 is performed to initiate the local and remote optical switches to interchange fibres N and S. Step S24 then examines once again for a remote fault on bearer numbered n~ If no fault is found, step S16 is performed to initiate a non-urgent alarm, followed by step S3 to ., ' ,, : ,~, . .
, ' - ~ .
: ' ' ' .
F20707CA ~ ~ ~7' interrogate the auxiliary channel. If a fau]t is detected, step Sl9 is performed to initiate an urgent alarm, and then step S3 is performed to interrogate the auxiliary ch~nnel.
If no fault is dekected at step S14, step S15 is performed to ascertain whether an output ~ail alarm exists on bearer numbered n. If no ~ault is d0tected step S19 is performed to initiate an urgent alarm, followed ~y step S3 to interrogate the auxiliary channel. If a fault is detected step S25 causes the appropriate electrical and optical switches to operate to interchange the opto-electronic converter N with the standby opto-electronic converter. Step S26 confirms the absence of an output fault. If no fault is present step S16 is performed to initiate a non-urgent alarm, followed by step S3 to interrogate the auxiliary channel. If step S26 confirms a fault, step Sl9 is performed to initiate an urgent alarm, and then step S3 is performed to interrogate the auxiliary channel.
Referring to Figure 3, an alternative embodiment of the present invention is shown wherein a point-to-multipoint configuration is employed. Again, common, identical equipment bears the same reference numeral. In this coniguration, optical switching means 7 and control logic , .
. :
,- : ' ': :
F20707C~
~ 12 -10a is provided at a hub site which is connected to 'che associated transmit and receive electro-optic converters 3,4 which in turn are electrically connec~e~ via line 6 to an electrical protection switching means. The optical swit~hing means 7 and control logic 10a is similarly connected to a number of systems 8, each of which comprise a worker path Wl and a standby path SB1, for example. Each path similarly comprises two optical fibre links for providing transmission in opposed directions. The optical fibre links are similarly terminated upon electro-optical fibre transmitters and receivers 3,4 in a similar manner as described with reference to Figure 2, and are similarly connected to electrical protection switching means, EPS 5.
A further optical switching means 7a and control logic 10 may be provided/ connected between the opposite end of the systems 8 and the electro-optic converters 3,4. This provision provides enhanced security and gives greater flexibility in securing the optical transmissions in the event of a failure. Only one standby electro-optic converter is required, at the central point end to serve the multi-point configuration.
Using the arrangement shown in Figure 3, each multipoint system is provided with its worker and standby paths and therefore, the optical switching means 7, and 7a , ., .
.. : .
F2070/C~ 2~ ~
when provided, are caused to operate to switch be'cween the two systems when the associated alarm and fault detection circuitry provided in the transmit and receive electro~optic converters 3,4 detect a fault.
In the arrangement of Figure 3 the objective is to reduce the provisioning cost at the hub site by enabling single standby equipment to be used to protect a number of worker systems with different destinations. At the hub site the control logic lOa also performs the sequence of Figure 4, already described. Since it is not possible for the remote control logic to communicate with the hub site in the event of simultaneous failure of both electro-optic converters the hub site also sequentially tests each remote standby equipment and fibre by connecting it to the hub standby equipment and checking its performance is within special limits by use of a test generator 9a and a test receiver 9b. If the remote site fails to respond to requests for information via the auxiliary channel 12 then failure of the remot~ worker and standby units is assumed and an urgent alarm raised.
The above description discusses two embodiments of the present invention, however it will readily be appreciated by those skilled in the art that further embodiments exist . . .
` '~ ' ' ' .
.
F20707CA ~ ~L5~3~;
within the spirit of the inventionO For example, the standby transmitters and receivers can be used to locate faults to subsystem level (e.y. transmitter, receiver, or fibre) by using the optical switches to provide local, and the electrical switches to provide remote loopback testing facilities.
. .
~. ; , .
, . ~ ': - ' : ' ' '
The present invention relates to the protection and testing of optical transmission apparatus.
Currently the only method of providing protection on such optical transmission apparatus is by electrical switchingO In these circumstances the protection arrangement consists of electro-optic converters permanently connected to the protected optical fibre and preceded by electrical switches. This prior art ~ortn of protection is shown in Figure 1 which shows a standby system and a worker number 1 system through to a worker number N system. Each system comprises a transmit and receive optical fibre 1,2, interconnecting a respective electro-optic converter 3,4 comprising a transmitter and receiver. The electro-optic converters 3,4 are connected to electrical protection switches 5. Control logic lOb is provided, and a control bus 13 interconnects the control logic lOb with the electrical protection switches 5. An alarm bus 11, and an auxiliary channel 12 interconnect the control logic lOb and the electro-optlc converters 3, 4. The apparatus described in Figure 1 is only applicable on a point-to-point basis and is intolerant of most multiple ~aults, (e.g. the . : . - :. . -.
: ~ ' , '" ' ,': , " ~ ~
: ', :
simultaneous failure of a part of the standby system and a part of a worker system~. Under these circumstances restoration cannot be achieved although sufficient workiny equipment is available. Faults cannot be located below system electro-optic converter -fibre- opto-electronic converter level without manual intervantion.
An aim of the present invention is to provide an optical transmission apparatus having a protection and testing facility which overcomes the above mentioned problems in an efficient and economical manner.
According to the present invention there is provided an optical transmission apparatus comprising at least one standby optical fibre transmission path and at least one worker optical fibre transmission path, terminated at each end by associated transmit and receive electro-optic converters which are connected to respective electrical protection switching means having input and output lines, characterised in that, at least one optical switching means is arranged to interface the electro-optic converters at one end of the optical fibre transmission paths, with the optical fibres, and switch the optical transmission hetween the worker and standby fibres when a fault is detected, by the electro-optic converters, in a transmission path.
.
~''',-' "' ~: ', ' .
, .
- , . ~ .
Accord.ing to an aspect of the present invention, an optical switching means is provided at each end of the optical fibre transmission paths which interface the electro-optic converters at each end of the paths, with the optical fibres.
According to a further aspect of the present invention, the optical switching means is arranged to interface a plurality of worker paths and a plurality of associated standby paths with a plurality of worker electro-optic converters and a single standby electro-optic converter.
According to yet a further aspect of the present invention, the optical switching means is arranged to provide local or remote loopback connections for testing purposes.
This arrangement of optical transmission apparatus has the advantage of being more tolerant in respect of multiple faults. The standby optical transmitter and receiver at each end of the standby optical transmission path, and the standby optical fibres themselves, can be used independently to by-pass faults on up to six systems simultaneously.
. .
.
.
- :
:
- ~, ': .
The standby transmikters and receivers can be used to locate faults to subsystem level (e.g. transmitter, receiver or fibre) by using the optical switches to provide local, and the electrical switches to provide remote loopback testing facilities.
In point-to-multipoint situations l:N protection can be employed at a central node wh~re one to one protection would previously had been required. This results in considerable economies at the central node.
Exemplary embodiments of the present invention will now be described with reference to the accompanying drawings wherein:-Figure 1 shows an optical fibre transmission systemaccording to a prior art arrangement, Figure 2 shows an optical transmission system in accordance with one embodiment of the present invention, Figure 3 shows an alternative embodiment of the present invention which shows a point-to-multipoint optical transmission system, and : ' ' ': ,' . ' :. :
... . : .
.
.
- : .
,' ~' ' ~' ' . '. '~ .
F20707C~
Figure 4 shows a ~low chart o~ the actions taken by control logic when an alarm is received~
Referring to Figure 2, the equipment which is identical to that of the prior art arrangement of Figure bear the same reference numerals. In Figure 2 a plurality of transmission paths are shown, a standby path SB, a first worker path Wl and an N worker path WN. It will be appreciated that a plurality of paths are provided between systems Wl and WN. Each transmission path comprises two optical fibres 1,2 for transmission in opposed directions.
The optical fibre 1 of each system is connected to an electro-optic transmitter 3 at one end and an electro-optic receiver ~ at the opposite end. The optical ~ibre 2 is connected to an electro-optic transmitter 3 and, to an electro-optic receiver 4 at its opposite end. The transmitters and receivers at each end are connected to associated electrical protection switches EPS 5 via corresponding electrical links 6.
Typically, the electro optic transmitters 3 and receivers 4 are provided by System 565 manufactured by the Plessey Company Limited. The Plessey System 565 is an optical fibre digital system operating at 565 Mbits/s. It - ., ::
' .. ' : ' ,.: ., ~ -' . .
- : . , - - , , . :,, .
-: - , .
.
is combined muldex and bothway line terminal which can handle four independent plesiochronous and CMI (code mark inversion) encoded data channels to CCITT recommendations.
The electro-optic transmitter 3/receiver 4 are also provided with an auxiliary channel 12 providing a supervisory system.
The electrical protection switches 5, each provide route protection terminating equipment at each end of a transmission path to be protected. Such equipment is known in the art. The equipments at each end are linked via a data communications link providing the means for co-ordinating the switching and control activities of the two equipments. When a bit error rate is worse than a threshold value, a signal is transmitted to the equipment indicating the deterioration of transmission quality. This signal is used to determine whether to switch to a different transmission path or not. The switching is carried out by use of RF relays. Failure of any part of the electrical protection switches will normally result in traffic being maintained on the worker bearers.
Fach optical fibre path end is interfaced with the associated electro-optic converters 3,4 by an optical switch means 7. An example of such a switch means is discussed in an article entitled "Switching in the Optical Domain" P. J.
, ... . .
, . .
.' ~', ' ' ~' ' ' ~ ,' ': :
Duthie, Plessey Research and Technology, Research Review 1989. A fault in any optical fibre route is detected electrically by the standard alarm and fault monitoring circuits built into the electro-optic converters 3,4. Upon detection of the breakdown, the control logic 10 associated with the optical switchiny means 7 receives the alarm and fault conditions from the converters 3,4 and operates the optical switching means in order to select an alternative path in order to restore correct transmission. The fault detection is performed at both ends of the transmission system by virtue of the fact that an optical switching means 7 and control logic 10 is provided at each end of the route.
The optical switching means 7 is so designed that the standby transmission equipment can be connected to any of the worker fibres or any of the worker equipments. Any of the worker equipments can also be connected to the standby transmission fibres.
Each electro-optic converter (3) provides an input fail alarm indication (I/PFn) and an output fail alarm indication (TxFn). Each opto-electric converter (4) provides an input fail alarm indication (FFn) and an output fail alarm indication (0/PFn). Where "n" indicates the working system number. The standby system alarms are designated "s 1l .
.
. . , : .
:
'' ' . :. ' ~ :
~' ' F20707C~ $~
All the above information is ~ed to the local control logic (10) via the Alarm bus (11). The local control loyic, which is realised as an Intel 8086 or similar microprocessor, also receives and transmits in~ormation from/to the remote control logic via the auxiliary channel (12), built into the electro-optic/opto-electronic converters. The auxiliary channel is triplicated for security and a majority decision taken at the receiving end.
The control commands are despatched via the control bus 13 to the optical switch means 7 and el~ctrical protection switches 5. On receipt of an alarm the control logic initiates the restoration sequence designated cycle B in Figure 4. On restoration of service it reverts to the monitoring cycle A of Figure 4, until repairs are completed and the standby system restored to normal. For diagnostic purposes a test generator 9a and receiver 9b are connected to the out-of-service "standby" system and provision is made for manual local, (optical) and remote (electrical) loop back. The necessary commands being initiated via the control logic 10 and auxiliary channel 12.
Referring to Figure 4, a flow chart is shown of the actions taken by the control logic 10 (Figures 2,3) when an alarm is received. Under normal, no fault conditions, a '`' .' . ~ .' ' .
;
. : ~ .": , ' ' - ~ ~
F20707CA ~3~ 5 ~
g monitoring cycle A is perform~d. In step, S1 the local alarm bus is interrogated for an alarm. In step S2, if no alarm is found, the auxiliary channel is interroyated in step S3. If a switching operation is required in step S4, the requested optical switch is operated in step S5, and step Sl is repeated. If in step S4, no switching operation is required, a check is made to see if a request has been made for alarm information. If it has, step S7 is performed and the alarm information is provided, and then step Sl is repeated. If no information is requested, step S1 is repeated.
When an alarm is found in step S2, cycle B is entered which is a restoration cycle. In steps S8-S12, checks are made to identify various faults respectively, as follows, input fail alarm on standby bearer I/PFs, input fail on bearer numbered 1 to n, I/PFn, transmit fail alarm on standby bearer TxFs, a remote input fail alarm on standby bearer FFs, an output fail alarm on standby bearer, O/PFs.
Each of these steps are performed and if an alarm is detected, step S16 is performed to initiate a non-urgent alarm, and then step S3 is performed to interrogate the auxiliary channel. If no faults are found during steps S8-S12, step 13 is performed to detect a fail alarm on the transmit bearer numbered 1 to n. If a fault is detected, . - ' ~ ' , . ~
- ~ .
:' ' ~ 3~ 3~
F20707C~
step Sl7 causes operation of the appropriate electrical and optical switch to interchange the electro-optic converter N
with the standby electro-opti~ converters. Step S1~
confirms whether the transmit fault in bearer n has been removed. If it has, t~len step S16 initiates a non-urgent alarm and the process returns to step S3 to interrogate the auxiliary channel. If the fault is still present step S19 is performed to initiate an urgent alarm, and the process returns to step S3.
I~ no fault is detected at step S13, step S14 is performed to ascertain if a fail alarm has been detected on the remote bearers numbered 1 to n. If it has, then step S20 requests the status of the remote transmit alarm of bearer number n. Step S21 acknowledges the response. If no response is received step S19 is performed to initiate an urgent alarm, followed by step S3 to interrogate the auxiliary channel. If a response is received, step S22 determines whether a electro-optic fault on remote bearer n is present. If it is, step S3 is performed. If no fault is present, step S23 is performed to initiate the local and remote optical switches to interchange fibres N and S. Step S24 then examines once again for a remote fault on bearer numbered n~ If no fault is found, step S16 is performed to initiate a non-urgent alarm, followed by step S3 to ., ' ,, : ,~, . .
, ' - ~ .
: ' ' ' .
F20707CA ~ ~ ~7' interrogate the auxiliary channel. If a fau]t is detected, step Sl9 is performed to initiate an urgent alarm, and then step S3 is performed to interrogate the auxiliary ch~nnel.
If no fault is dekected at step S14, step S15 is performed to ascertain whether an output ~ail alarm exists on bearer numbered n. If no ~ault is d0tected step S19 is performed to initiate an urgent alarm, followed ~y step S3 to interrogate the auxiliary channel. If a fault is detected step S25 causes the appropriate electrical and optical switches to operate to interchange the opto-electronic converter N with the standby opto-electronic converter. Step S26 confirms the absence of an output fault. If no fault is present step S16 is performed to initiate a non-urgent alarm, followed by step S3 to interrogate the auxiliary channel. If step S26 confirms a fault, step Sl9 is performed to initiate an urgent alarm, and then step S3 is performed to interrogate the auxiliary channel.
Referring to Figure 3, an alternative embodiment of the present invention is shown wherein a point-to-multipoint configuration is employed. Again, common, identical equipment bears the same reference numeral. In this coniguration, optical switching means 7 and control logic , .
. :
,- : ' ': :
F20707C~
~ 12 -10a is provided at a hub site which is connected to 'che associated transmit and receive electro-optic converters 3,4 which in turn are electrically connec~e~ via line 6 to an electrical protection switching means. The optical swit~hing means 7 and control logic 10a is similarly connected to a number of systems 8, each of which comprise a worker path Wl and a standby path SB1, for example. Each path similarly comprises two optical fibre links for providing transmission in opposed directions. The optical fibre links are similarly terminated upon electro-optical fibre transmitters and receivers 3,4 in a similar manner as described with reference to Figure 2, and are similarly connected to electrical protection switching means, EPS 5.
A further optical switching means 7a and control logic 10 may be provided/ connected between the opposite end of the systems 8 and the electro-optic converters 3,4. This provision provides enhanced security and gives greater flexibility in securing the optical transmissions in the event of a failure. Only one standby electro-optic converter is required, at the central point end to serve the multi-point configuration.
Using the arrangement shown in Figure 3, each multipoint system is provided with its worker and standby paths and therefore, the optical switching means 7, and 7a , ., .
.. : .
F2070/C~ 2~ ~
when provided, are caused to operate to switch be'cween the two systems when the associated alarm and fault detection circuitry provided in the transmit and receive electro~optic converters 3,4 detect a fault.
In the arrangement of Figure 3 the objective is to reduce the provisioning cost at the hub site by enabling single standby equipment to be used to protect a number of worker systems with different destinations. At the hub site the control logic lOa also performs the sequence of Figure 4, already described. Since it is not possible for the remote control logic to communicate with the hub site in the event of simultaneous failure of both electro-optic converters the hub site also sequentially tests each remote standby equipment and fibre by connecting it to the hub standby equipment and checking its performance is within special limits by use of a test generator 9a and a test receiver 9b. If the remote site fails to respond to requests for information via the auxiliary channel 12 then failure of the remot~ worker and standby units is assumed and an urgent alarm raised.
The above description discusses two embodiments of the present invention, however it will readily be appreciated by those skilled in the art that further embodiments exist . . .
` '~ ' ' ' .
.
F20707CA ~ ~L5~3~;
within the spirit of the inventionO For example, the standby transmitters and receivers can be used to locate faults to subsystem level (e.y. transmitter, receiver, or fibre) by using the optical switches to provide local, and the electrical switches to provide remote loopback testing facilities.
. .
~. ; , .
, . ~ ': - ' : ' ' '
Claims (6)
1. Optical transmission apparatus comprising at least one standby optical fibre transmission path and at least one worker optical fibre transmission path, terminated at each end by associated transmit and receive electro-optic converters which are connected to respective electrical protection switching means having input and output lines, characterised in that, at least one optical switching means is arranged to interface the electro-optic converters at one end of the optical fibre transmission paths, with the optical fibres, and switch the optical transmission between the worker and standby fibres when a fault is detected, by the electro-optic converters, in a transmission path.
2. Optical transmission apparatus as claimed in claim 1, wherein an optical switching means is provided at each end of the optical fibre transmission paths which interface the electro-optic converters at each end of the paths, with the optical fibres.
3. Optical transmission apparatus as claimed in claim 1, wherein optical switching means is arranged to interface a plurality of worker paths and a plurality of associated standby paths with a plurality of worker electro-optic converters and a single standby electro-optic converter.
4. Optical transmission apparatus as claimed in claim 2, wherein microprocessor based control logic is connected to the electro-optic converters by an alarm bus, and to the electrical protection switches and optical switching means by a control bus, said control logic being arranged to monitor alarm indications on the alarm bus, and the microprocessor is programmed to take appropriate action based upon the alarm indications and instruct the electrical protection switches and the optical switching means to operate appropriate switching devices when a fault is identified, to set-up an alternative transmission path.
5. Optical transmission apparatus as claimed in claims 3 and 4, wherein the standby electro-optic converter is located at a hub site, and the control logic at the hub site monitors the alarm indications.
6. Optical transmission apparatus as claimed in any preceding claim, wherein the optical switching means is arranged to provide local or remote loopback connections for testing purposes.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB898910957A GB8910957D0 (en) | 1989-05-12 | 1989-05-12 | Optical transmission apparatus |
| GB8910957.3 | 1989-05-12 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2015926A1 true CA2015926A1 (en) | 1990-11-12 |
Family
ID=10656643
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002015926A Abandoned CA2015926A1 (en) | 1989-05-12 | 1990-05-02 | Optical transmission apparatus |
Country Status (3)
| Country | Link |
|---|---|
| US (1) | US5069521A (en) |
| CA (1) | CA2015926A1 (en) |
| GB (2) | GB8910957D0 (en) |
Families Citing this family (84)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5313456A (en) * | 1989-03-03 | 1994-05-17 | Fujitsu Limited | Data link protecting system |
| CA2054443C (en) * | 1990-10-30 | 1995-11-07 | Kazuo Yamane | Switching system of optical transmission lines for protecting from trouble |
| WO1992011709A1 (en) * | 1990-12-18 | 1992-07-09 | Aster Corporation | Optical communication monitoring and control |
| BE1004668A3 (en) * | 1991-04-02 | 1993-01-05 | Bell Telephone Mfg | PROTECTION DEVICE FOR AN OPTICAL transmitter / receiver device. |
| US5191626A (en) * | 1991-04-22 | 1993-03-02 | The Trustees Of Columbia University In The City Of New York | Optical communications system and method |
| US5241610A (en) * | 1991-09-03 | 1993-08-31 | Scientific-Atlanta, Inc. | Optical switching in a fiber communication system and method using same |
| US5218465A (en) * | 1991-09-03 | 1993-06-08 | Motorola, Inc. | Intelligent interconnects for broadband optical networking |
| JP2528225B2 (en) * | 1991-09-18 | 1996-08-28 | 富士通株式会社 | Transmission line switching method |
| US5212578A (en) * | 1991-10-02 | 1993-05-18 | At&T Bell Laboratories | Selection of transmission facilities using optical wavelength division multiplexing |
| WO1993014574A1 (en) * | 1992-01-10 | 1993-07-22 | Fujitsu Limited | Optical transmission system |
| US5337316A (en) * | 1992-01-31 | 1994-08-09 | Motorola, Inc. | Transceiver self-diagnostic testing apparatus and method |
| US6147783A (en) * | 1992-02-18 | 2000-11-14 | Fujitsu Limited | Optical transmission system wherein protection terminal equipment converts alarm indication signal before relaying same to working terminal equipment |
| US5285512A (en) * | 1992-06-24 | 1994-02-08 | Litton Systems, Inc. | Fiber optic transceiver with integrated coupler |
| US5479608A (en) * | 1992-07-17 | 1995-12-26 | Alcatel Network Systems, Inc. | Group facility protection in a digital telecommunications system |
| US5329520A (en) * | 1992-07-17 | 1994-07-12 | Alcatel Network Systems, Inc. | High-speed facility protection in a digital telecommunications system |
| US5442623A (en) * | 1992-08-17 | 1995-08-15 | Bell Communications Research, Inc. | Passive protected self healing ring network |
| US5245680A (en) * | 1993-02-05 | 1993-09-14 | Unisys Corporation | Grin lens optical backplane with dual transmitter-receiver repeaters |
| JPH06244805A (en) * | 1993-02-17 | 1994-09-02 | Sony Corp | Optical signal transmission device |
| EP0637879A1 (en) * | 1993-04-16 | 1995-02-08 | Nec Corporation | Hitless switching apparatus and method for optical network |
| EP0700605B1 (en) * | 1993-05-28 | 1998-08-05 | Siemens Aktiengesellschaft | Equivalent circuit process for a transmission device for the bidirectional transmission of digital signals and arrangement for implementing the process |
| JPH0786988A (en) * | 1993-09-16 | 1995-03-31 | Fujitsu Ltd | Device and method for pca transmission |
| US5539564A (en) * | 1993-09-22 | 1996-07-23 | Nippon Telegraph And Telephone Corporation | Point-to-multipoint optical transmission system |
| JP3308087B2 (en) * | 1994-01-11 | 2002-07-29 | 富士通株式会社 | Optical communication device |
| US5864414A (en) * | 1994-01-26 | 1999-01-26 | British Telecommunications Public Limited Company | WDM network with control wavelength |
| DE4421305C2 (en) * | 1994-06-17 | 2002-07-18 | Siemens Ag | Circuit arrangement for switching between the two fibers of a double optical fiber connection running between two nodes |
| JPH08288981A (en) * | 1995-04-18 | 1996-11-01 | Fujitsu Ltd | Line changeover system for duplex transmitter between different modes |
| US5862125A (en) * | 1995-06-07 | 1999-01-19 | Mci Communication Corporation | Automated restoration of unrestored link and nodal failures |
| JP3582030B2 (en) * | 1995-07-05 | 2004-10-27 | 富士通株式会社 | Cross connect device |
| JP3432958B2 (en) * | 1995-07-21 | 2003-08-04 | 富士通株式会社 | Optical transmission system and transmission line switching control method |
| US5625478A (en) * | 1995-09-14 | 1997-04-29 | Lucent Technologies Inc. | Optically restorable WDM ring network using simple add/drop circuitry |
| KR0159663B1 (en) * | 1995-10-28 | 1998-12-01 | 김광호 | Optical data transmission device realizing duplexing of optical data transmissions |
| US5731887A (en) * | 1995-12-22 | 1998-03-24 | Mci Communications Corporation | System and method for photonic facility and line protection switching |
| 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 |
| US5884017A (en) * | 1995-12-29 | 1999-03-16 | Mci Communications Corporation | Method and system for optical restoration tributary switching in a fiber network |
| US6108113A (en) * | 1995-12-29 | 2000-08-22 | Mci Communications Corporation | Method and system for transporting ancillary network data |
| US6285475B1 (en) | 1995-12-29 | 2001-09-04 | Mci Communications Corporation | Method and system for detecting optical faults in a network fiber link |
| US5710846A (en) * | 1996-03-26 | 1998-01-20 | Rf Systems, Inc. | Self-calibrating optical fiber switch |
| JP3473262B2 (en) * | 1996-04-05 | 2003-12-02 | 株式会社日立製作所 | Packet communication device |
| JP3639383B2 (en) * | 1996-04-15 | 2005-04-20 | 富士通株式会社 | Optical transmission system |
| US5712936A (en) * | 1996-06-27 | 1998-01-27 | Mci Communications Corporation | Hybrid bi-directional three color wave division multiplexer and method using same |
| US5903370A (en) * | 1996-06-28 | 1999-05-11 | Mci Communications Corporation | System for an optical domain |
| US5793909A (en) * | 1996-09-09 | 1998-08-11 | Lucent Technologies Inc. | Optical monitoring and test access module |
| DE19649870A1 (en) * | 1996-12-02 | 1998-06-04 | Alsthom Cge Alcatel | Optical switching unit, in particular for switching over to replacement components in optical transmission systems |
| US6198720B1 (en) | 1996-12-26 | 2001-03-06 | Alcatel Usa Sourcing, L.P. | Distributed digital cross-connect system and method |
| US5901024A (en) * | 1996-12-23 | 1999-05-04 | Alcatel Usa Sourcing, L.P. | Apparatus and method for circuit protection |
| JPH10209964A (en) * | 1997-01-28 | 1998-08-07 | Fujitsu Ltd | Wavelength multiplex transmission/reception equipment, optical transmission system and redundant system switching method for the same |
| JP3854372B2 (en) * | 1997-07-03 | 2006-12-06 | 株式会社日立コミュニケーションテクノロジー | Optical cross-connect device |
| US6362905B1 (en) * | 1997-02-24 | 2002-03-26 | Hitachi, Ltd. | Optical crossconnect apparatus and optical transmission system |
| DE19712750A1 (en) * | 1997-03-26 | 1998-10-01 | Alsthom Cge Alcatel | Test method for a network element of an optical communication system and network element |
| EP0889665B1 (en) * | 1997-07-03 | 2009-10-07 | Hitachi, Ltd. | Optical crossconnect apparatus and optical transmission system |
| WO1999005802A1 (en) * | 1997-07-23 | 1999-02-04 | Adc Telecommunications, Inc. | Multiple-line proctection for telecommunications network |
| US6057948A (en) * | 1997-11-03 | 2000-05-02 | Ciena Corporation | Protection switch optical communications system |
| JP3753866B2 (en) * | 1998-07-01 | 2006-03-08 | 株式会社日立製作所 | Self-relieving optical network |
| US6574686B1 (en) * | 1999-11-20 | 2003-06-03 | Lucent Technologies Inc. | Method for overcoming faults in an ATM I/O module and lines connected thereto |
| AU1950501A (en) * | 1999-12-13 | 2001-06-18 | Adc Telecommunications, Incorporated | Monitored redundant switch apparatus and method |
| US20010046074A1 (en) * | 2000-05-25 | 2001-11-29 | Sunao Kakizaki | Protection switching apparatus for 1 + 1 optical transmission lines |
| EP1182903A1 (en) * | 2000-08-21 | 2002-02-27 | Lucent Technologies Inc. | Point-to-point protection in point-to-multipoint networks |
| US7463467B2 (en) * | 2001-07-06 | 2008-12-09 | Schweitzer Engineering Laboratories, Inc. | Relay-to-relay direct communication system and method in an electric power system |
| US7701683B2 (en) * | 2001-07-06 | 2010-04-20 | Schweitzer Engineering Laboratories, Inc. | Apparatus, system, and method for sharing output contacts across multiple relays |
| US6766482B1 (en) | 2001-10-31 | 2004-07-20 | Extreme Networks | Ethernet automatic protection switching |
| US7187865B2 (en) * | 2001-11-13 | 2007-03-06 | Nortel Networks Limited | Hybrid photonic/electronic switching in a multi-channel network |
| CA2365752A1 (en) * | 2001-12-20 | 2003-06-20 | Pierre Coll | Data communication apparatus with distributed traffic protection switching system |
| EP1324521B1 (en) * | 2001-12-20 | 2011-05-25 | Ciena Luxembourg S.a.r.l. | Data communication apparatus with distributed traffic protection switching system |
| US6832014B1 (en) * | 2002-02-08 | 2004-12-14 | Marconi Communications, Inc. | Backplane wire and noise eliminator tube |
| US7120203B2 (en) * | 2002-02-12 | 2006-10-10 | Broadcom Corporation | Dual link DVI transmitter serviced by single Phase Locked Loop |
| WO2004008833A2 (en) * | 2002-07-24 | 2004-01-29 | Ciena Corporation | Method and system for providing protection in an optical communication network |
| US7362697B2 (en) * | 2003-01-09 | 2008-04-22 | International Business Machines Corporation | Self-healing chip-to-chip interface |
| US20050089331A1 (en) * | 2003-10-03 | 2005-04-28 | Near Margalit | Assured connectivity fiber-optic communications link |
| ATE492078T1 (en) * | 2004-10-29 | 2011-01-15 | Alcatel Lucent | OPTICAL ACCESS NODE |
| US7460590B2 (en) * | 2005-09-14 | 2008-12-02 | Schweitzer Engineering Laboratories, Inc. | Handheld communication tester and method for testing direct serial communication capability of an intelligent electronic device in a power system |
| US8477596B2 (en) * | 2006-01-30 | 2013-07-02 | Infinera Corporation | Application of hardware-based mailboxes in network transceivers and distributed approach for predictable software-based protection switching |
| CN100568815C (en) * | 2006-02-28 | 2009-12-09 | 中兴通讯股份有限公司 | A kind of system for transmitting single-fiber-optic two-way wavelength division multiplexing and guard method thereof |
| US8160453B1 (en) | 2006-03-30 | 2012-04-17 | Rockstar Bidco, LP | Protection switching with transmitter compensation function |
| US8861952B2 (en) * | 2007-02-28 | 2014-10-14 | Finisar Corporation | Redundancy and interoperability in multi-channel optoelectronic devices |
| WO2008134750A2 (en) * | 2007-04-30 | 2008-11-06 | Finisar Corporation | Eye safety and interoperability of active cable devices |
| JP2010161750A (en) * | 2009-01-09 | 2010-07-22 | Sony Corp | Signal transmission apparatus, signal reception device, and signal transmission system |
| US8427131B2 (en) * | 2009-06-12 | 2013-04-23 | Schweitzer Engineering Laboratories Inc | Voltage regulation at a remote location using measurements from a remote metering device |
| US9256232B2 (en) | 2009-06-12 | 2016-02-09 | Schweitzer Engineering Laboratories, Inc. | Voltage regulation using multiple voltage regulator controllers |
| EP2449698A4 (en) * | 2009-06-30 | 2015-01-28 | Ericsson Telefon Ab L M | Method and arrangement for enabling link status propagation |
| US8476874B2 (en) * | 2009-10-13 | 2013-07-02 | Schweitzer Engineering Laboratories, Inc | Systems and methods for synchronized control of electrical power system voltage profiles |
| US8391707B2 (en) * | 2009-11-13 | 2013-03-05 | Verizon Patent And Licensing Inc. | Maintenance friendly optical fiber switching system |
| US8433190B2 (en) * | 2009-11-13 | 2013-04-30 | Verizon Patent And Licensing Inc. | Hot-swapping in-line optical amplifiers in an optical network |
| US8787147B2 (en) * | 2010-10-19 | 2014-07-22 | Ciena Corporation | Ten gigabit Ethernet port protection systems and methods |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS608667B2 (en) * | 1980-10-09 | 1985-03-05 | 株式会社明電舎 | Loop data highway system |
| JPH0695688B2 (en) * | 1986-08-26 | 1994-11-24 | 日本電気株式会社 | Loopback control device |
-
1989
- 1989-05-12 GB GB898910957A patent/GB8910957D0/en active Pending
-
1990
- 1990-05-01 GB GB9009768A patent/GB2233851B/en not_active Expired - Lifetime
- 1990-05-02 CA CA002015926A patent/CA2015926A1/en not_active Abandoned
- 1990-05-07 US US07/519,217 patent/US5069521A/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| GB9009768D0 (en) | 1990-06-20 |
| GB2233851A (en) | 1991-01-16 |
| US5069521A (en) | 1991-12-03 |
| GB2233851B (en) | 1993-06-16 |
| GB8910957D0 (en) | 1989-06-28 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US5069521A (en) | Optical transmission apparatus | |
| US7272314B2 (en) | Optical crossconnect apparatus and optical transmission system | |
| AU679131B2 (en) | Protection switching apparatus and method | |
| CA1321001C (en) | Transmission line switching system | |
| KR940006365A (en) | Distribution control method and apparatus for performing automatic protective switching | |
| KR940006367A (en) | Method and system for protecting group facilities in digital telecommunication systems | |
| JPH0695688B2 (en) | Loopback control device | |
| CA2318077A1 (en) | System and method for increasing the robustness of an optical ring network | |
| EP0617525B1 (en) | Light path switching system | |
| JP3854372B2 (en) | Optical cross-connect device | |
| GB2175775A (en) | Data transmission system | |
| KR100333954B1 (en) | The Mehod and Apparatus of Dual Operation and Fault Detection in Optical Network Using Single Core | |
| JP2601193B2 (en) | Optical transmission system | |
| US6650449B1 (en) | Method and device for network protection | |
| JP3322482B2 (en) | Switching and switching back device | |
| JPH10313278A (en) | Star type optical subscriber transmission system | |
| DK166525B1 (en) | PROCEDURE FOR CHECKING AN INTERFACE COMPONENT | |
| JP2615762B2 (en) | Loop type optical transmission equipment | |
| JP3284509B2 (en) | Working spare switching method | |
| CA1246173A (en) | Method of operating a two-wire local area network such that marginal components in the secondary loop are located | |
| JP3484667B2 (en) | Line monitoring system | |
| JPS60106233A (en) | Transmission line switching device | |
| JPH1198075A (en) | Transmission line supervisory device | |
| JPH04192941A (en) | Lan communication system | |
| JPS6052124A (en) | Route switching control system |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| FZDE | Discontinued |