1. Cutover preparation
Resource inspection: extract the resource situation of the optical cable to be cut over through the resource management system for on-site verification, as part of reporting the cutover plan.
Cutover report approval: report cutover according to cutover report requirements
Resource review: After the cutover is approved, the resource usage of the cable section to be cut over will be checked again on site and the cutover site will be found out.
Equipment preparation: including instruments and meters for cutover, vehicles, generators, tents, etc.
Preparation for machine line contact: machine line contact, confirm cutover report, contact person and telephone number
Site preparation: advance deployment of optical cables for cutover, manhole ventilation, site pretreatment, etc.
2. On-site cutover implementation
3. Management after cutover
4. Cutover plan
4.1 Inverted fiber solution
The fiber reversal solution is the preferred solution for fiber optic cable cutover and uninterrupted business. It is suitable for fiber optic cable line cutover with spare fiber optic cable routing. This solution mainly emphasizes the coordination and cooperation of the maintenance and line maintenance departments. The specific operation method is that the machine room maintenance personnel will need to cut All services in the connected optical cable are transferred to the spare optical cable route, and the vacant optical cable is cut over by the line personnel.
4.2 Tuning circuit scheme
The circuit adjustment method is a method in which the circuits affected during the optical cable cutover process are adjusted to the circuits in other optical cables, and the cutover will be performed after the optical cable is vacated.
At the same time, the circuit adjustment method is used as an auxiliary method of the fiber reversal mode. When the spare fiber resources are not many, the fiber reversal is performed on the large-capacity and important circuits, and the circuit is adjusted for other circuits.
4.3 Longitudinal section plan
The longitudinal section method is a cutover method in which there is no spare optical cable route and the circuit cannot be called out. It is necessary to use the method of opening the skylight of the optical cable to connect the intervening optical cable to the original optical cable one by one or the bundle of tubes. The longitudinal section method is aimed at the repair of the individual blocking cores of the optical cable lines, and does not affect other fibers with good performance in use.
Steps of longitudinal section pipe cutting and splicing:
The computer room personnel call out the system in the pipe to be cut according to the circuit scheduling plan;
On-site personnel longitudinally cut and strip the optical cable to be cut;
Longitudinal section of the beam tube, check with the personnel in the machine room, confirm the beam tube to be cut and cut the tube for connection;
The computer room personnel perform simultaneous monitoring to confirm that the optical fiber transmission characteristics are qualified and the fiber sequence is correct, and then return to the original system according to the circuit scheduling plan. After normalization, notify the cutover site that the bundle tube fiber is cut and ready for the next step;
According to the above method, both sides of the machine line cut other bundles one by one.
Vertical section cutover steps one by one:
The computer room personnel call out the system in the core to be cut and spliced one by one according to the circuit scheduling plan;
On-site personnel longitudinally cut and strip the optical cable to be cut;
Longitudinal section tube, check with the personnel in the machine room, confirm the fiber core pair to be cut and cut the fiber core pair for splicing;
The computer room personnel conduct synchronous monitoring to confirm that the optical fiber transmission characteristics are qualified and the fiber sequence is correct, and then revert back to the original system according to the circuit scheduling plan. After normality is restored, notify the cutover site that the fiber core pair is cut and ready for the next step;
According to the above method, both sides of the machine line cut other fiber core pairs one by one.
Use of longitudinal section plan:
Longitudinal splicing is aimed at the repair of non-total resistance failures of optical cables, and it is not suitable to use full resistance failures.
Long-distance splicing is suitable for long-distance trunk optical cable non-full resistance fault repair. The local network fiber optic cable is not recommended because of more failures and fewer cores.
Particular care should be taken in longitudinal splicing to avoid damaging the intact bundle tube fiber.
The length of the intervening optical fiber or cable is 50-100 meters.
5. Problems that should be paid attention to in optical cable cutover
5.1 Formulation of cutover plan
Report the cutover application report in advance in accordance with the cutover reporting time limit, and specify the paragraph name, relay disconnection, cutover reason, location, time, cooperating personnel, cutover personnel, vehicles, instruments and equipment in the cutover plan. The content of the cutover scheduling plan and the cutover emergency scheduling plan are described in detail. The following matters should be noted during cutover:
1) Selection of cutover point
The cutover point should choose the original joint position as much as possible, taking into account the transmission index, the convenience of operation and other factors, and reduce the joint loss caused by the cutover as much as possible. If the cutover point is far away from the original cutover point and the transmission index allows, you can place the cutover point in a suitable position in the route.
2) Division of labor for cutover personnel, vehicles, instruments and equipment
Arrange and implement the personnel list, contact information, vehicles, instruments and equipment of the succession group and the test group should be reasonable, and personal factors, site factors, etc. should be fully considered. In the case of insufficient local manpower, you should contact the higher-level department as soon as possible to request additional assistance in personnel, vehicles, instruments and equipment. It is required to have a backup instrument at the cutover site and the test site to meet the timely dispatch when a certain instrument fails during the cutover process.
Implement the specific responsibilities of the cutover commander and the responsible and cooperating personnel of the succession and test teams, and specify the specific contact methods. Generally, at least two or more contact methods should be considered to ensure smooth communication between the cutover points and between the cutover point and the test point during the entire cutover process.
3) Cutover scheduling plan
It is necessary to fully understand the open status of the system, the status of the spare core and the core chromatogram table of the new/old cable. It is necessary to work out the sequence and steps for detailed scheduling, proofreading, identification, and connection of each fiber core and each system, and strive to restore the circuit in the shortest time.
When there is a spare bundle tube in the optical cable, the spare bundle tube should be used for scheduling, or the open systems in several bundle tubes can be dispatched together, and a bundle tube can be used for scheduling. When the spare bundle tube cannot be guaranteed, as long as there are two spare fibers with good performance in the optical cable, it can meet the needs of fiber core dispatching with service. If there is no or insufficient fiber core for fiber core dispatch, try to follow The priority of circuit scheduling is to schedule important business circuits.
4) Emergency dispatch plan
Due to the use of service cutover, there are certain risks. In order to avoid accidents in the process of optical cable stripping and connection, causing circuit interruption, or business interruption due to other reasons, a detailed circuit scheduling emergency plan should be formulated before the cutover. If the fiber is interrupted due to misoperation, the fiber should be reconnected as soon as possible, or the circuit should be adjusted to quickly restore the system. Therefore, it is essential to formulate detailed troubleshooting methods and emergency contact methods in the emergency dispatch plan.
5.2 Preparations before cutover
After the cutover application report is approved, the preparatory work before the cutover becomes particularly important. We should fully prepare for the cutover, which is mainly reflected in the following aspects.
1) Collect and organize the original data of the route.
2) Familiar with the performance of the transmission equipment in use, and record the performance parameters of the cutover section, such as optical power and return loss.
3) Check whether the laying of the new optical cable is safe and reasonable, and test and confirm the parameters of the optical cable.
4) Check the cutover equipment and tools as well as communication tools to ensure the normal use of various instruments and machines.
5) On-site verification of the cutover scheduling plan, check whether the cutover site has changed, whether the equipment in the computer room and the pigtail have changed.
6) The cutover team arrived at the cutover site 2 hours before the cutover to make preparations, excavate the operation pit and the splice pit, including checking the cutover optical cable lines, taking good on-site protection and various safety measures and correcting Stripping of new optical cable. For directly buried optical cables, routing detectors are used to detect the specific location and buried depth. For overhead optical cables, check the optical cable reservations. Check and arrange the connection tools to check whether the communication method is unblocked.
7) Each test team arrives at the site one hour in advance, confirms the position of the ODF rack, and does a good job of marking the pigtails. At the same time, the fiber preparation and dispatching fibers are retested and checked and registered. Check the power and lighting conditions of the computer room, contact the network management center and the cutover point, confirm that the contact tools are intact, and make all preparations.
8) Convene all cutover personnel to hold a special meeting with business cutover 4 hours before the cutover, further inform the operation steps of the cutover plan, and implement the in place of the cutover personnel, vehicles, instruments and equipment, and the attention paid during the cutover matter.
5.3 Formal cutover
When the cutover approval time is reached, the cutover will officially start, and the cutover and test personnel should operate in accordance with the previously formulated cutover plan. The following matters should be noted during the operation:
1) The tester must use a light source and an optical power meter to test the spare fiber to ensure that the transmission characteristics of each fiber are good, and to determine whether the fiber has a mandarin duck fiber.
2) The tester must clean the pigtail head and flange before plugging and unplugging the optical fiber.
3) The tester should notify the cutover site personnel to do a microbend test before fiber breakage to determine the correctness of the fiber core, especially when there are mandarin duck fibers, and to carefully check the accuracy of each fiber. In addition, when the tester finds that the splicing quality is unqualified during the test, he should promptly notify the splicing personnel to re-splice.
4) The splicing personnel must follow the chromatogram and fiber cores established in the cutover plan to prevent wrong fibers and wrong tubes. During the splicing process, care should be taken to avoid injury to the fiber in use. Once the fiber in use is injured, the splicing should be restored as soon as possible, or the circuit should be adjusted as soon as possible.
5) The tester should synchronize the system fiber by fiber and system by system. If the system cannot recover quickly after fiber adjustment, you need to restore the fiber to the original position, and then determine the cause of the failure, which can be confirmed by the rack lights, CD warning lights and network management center, and finally confirmed by the network management center.
6) The tester should record in detail the attenuation value of each fiber before and after the splicing, as well as the attenuation value of each joint position, including the two test values of light source, optical power meter and OTDR. The fiber length should also be recorded in detail.
7) The second fiber adjustment should be done after all the empty fibers of the cut joints are completely spliced, and it is confirmed that the splicing performance is good, there is no wrong fiber or wrong pipe phenomenon, and the spliced empty fiber tray has been placed in the fiber reel box at the splicing point Afterwards.
8) The tester should record the recovery time of each interruption in detail.
5.4 Implementation of box sealing
When all the fibers have been connected and stored in the fiber reel box, the rack warning light and the CD warning light disappear, and the network management center confirms that the box can be sealed. The following issues should also be paid attention to in the box sealing work:
1) Directly buried optical cable joint box should be installed with monitoring tail cable, the joint box should be sealed, and buried in the joint pit dug in advance, and the reserved optical cable reel should be reserved and buried. After the overhead optical cable connector box is installed, it should be fixed on the pole, and the installation of the reserved basket and the reserved coiling of the optical cable should be done.
2) The tester should do a good job of monitoring during the installation of the connector box, and analyze whether the optical fiber has attenuation changes during the installation of the connector box.
3) When the fiber core is welded and safely placed in the fiberboard at each cutover point, the tester in the equipment room should be notified to perform the test before sealing the box. After the connector box is sealed, the tester in the equipment room should perform the test again. When the connector box is buried in the connector pit or fixed on the pole, the tester in the equipment room should also test continuously and observe the changes of the optical fiber attenuation parameters.
4) After all cutover operations are completed, contact the network management center to confirm that there is no abnormality, and then check the tools and meters and leave the site.
5.5 Follow-up work
After the cutover is completed, the cutover completion data should be reported in time according to the time limit, and the data that needs to be modified and improved due to the business cutover, such as the optical cable line equipment change table, the mark/pole length comparison table, and the optical cable routing diagram , Maintenance drawings, wiring diagrams, etc.
6. Mistakes that are prone to occur in optical cable cutover
1) When there are multiple new optical cables of the same specification and model to be cut in the same cutover site, if the two ends of each optical cable are not marked with the same color when the cables are laid out, and they are in the same pipe hole, it is very easy to make mistakes during the cut.
2) The usual practice for the old optical cable to be cut over is to mark the reserved end with red tape, but after the old optical cable is pulled out of the manhole, should the left end or the right end of the red tape be sawn during cutover? It is very easy to make mistakes. In fact, blue tape should also be used to mark the discarded end. It will not go wrong by sawing between the red tape and the blue tape and keeping the red end.
3) In the same section of old optical cable to be cut over, because there are multiple splice boxes and various types of optical cables, the splice box is not opened before the cut and the fiber is recorded and the wrong fiber is inevitable. .
4) In the fiber optic cable cutover of the incoming city line, since the fiber optic cables in different directions go through the same pipe, it is easy to get the direction wrong during cutover.
5) In the on-site cutover safety management, a little carelessness will cause a safety accident. If you enter the manhole without proper ventilation, use an open flame in the manhole, no warning signs are set around the manhole, no warning signs are set around the manhole, no warning signs are set when pumping water, smoke while refueling the oiler, and work on the pole without checking with a test pencil , Without the approval of the person in charge of the cutover point, the cable was opened and so on.
