Hello,
Today, I would like to share with you how to solve the problem, when OSN3500 linear multiplex section switching test part of the service fails.
Problem Description
As shown in the figure: ABCD 4 site linear multiplexing chain network, when doing linear multiplexing section switching tests in each section area, it is found that after the main fiber between BC is disconnected, there is no alarm for AD services, and there is no alarm between AC For 2M services, site C reports TU_AIS, site A reports LP_RDI; the optical fiber recovery alarm between BC disappears; after the main optical fiber between CDs is disconnected, there is no alarm for AD services, and 2M services between CDs is reported by site C TU_AIS, D site reports LP_RDI, and the optical fiber recovery alarm between CDs disappears;
Alarm
TU_AIS, LP_RDI
Possible reason
1- The switching of the linear multiplex section fails;
2- The configuration parameters of the linear multiplex section protection group are wrong;
3- The protection channel of the linear multiplex section is abnormal;
4- Linear multiplex section protection channel line single board failure, cross single board failure;
5- Physical and logical connection errors;
Handling Process
1- After the linear multiplex section is switched, the switch site has a multiplex section down alarm, only the switching point services has a TU_AIS alarm, and other services have no alarms, indicating that the linear multiplex section is switched normally after the fiber is cut; the possibility of linear multiplex section switching failure is excluded;
2- Check the parameters of the linear multiplex section protection group, the protection unit protects the board logically and correctly;
3- Check the switching status of the BC network element linear multiplex section respectively, and the protection channel is normal;
4- There are other services in the VC4 time slot channel where the TU_AIS alarm is generated at the C site, and loopback operations cannot be performed on VC4; find an idle VC4 between the BCs, configure the 2M landing service between the BCs for testing, and use the BC as the main fiber After disconnection, the 2M service at site C reports TU_AIS, and the 2M service at site B reports LP_RDI. The fault remains. The third VC4 in slot 11 of the B site is opened. The alarm at station B disappears, and the alarm at station C on the outer ring does not disappear; at site C The third VC4 in slot 2 of 11 is connected to the inner ring, the alarm at site C disappears, and the alarm at station B on the outer ring does not disappear; eliminate the crossover and line board failures at the BC site;
5- It is suspected that the BC backup channel is wrongly connected. The main fiber between the BC sites is restored. Turn off the 2 lasers in the 11 slot of the C site, and the B site 11 slot 1 port receives the light to report R_LOS is normal, and closes the B site 11 slot 1 port Laser, the light receiving of port 11 in slot 11 at site C reports abnormal R_LOS, turn off the laser of port 11 in slot 11 at site C, and the light receiving of port 2 in slot 11 at site D reports R_LOS normal, turn off the laser of port 11 in slot 11 at site D and the 2 laser at site C The light receiving of port 1 in slot 11 reports an abnormal R_LOS; by turning off the laser, it is found that the RX fiber of port 11 in slot 2 and the RX fiber in slot 1 of 11 slot 1 RX fiber mandarin ducks, which causes the linear multiplex section to fail. Set the J0/J1 overhead byte, and check whether the set J0/J1 byte can be received normally at the opposite end to judge whether the optical fiber connection is normal);
6- After swapping the 11-slot 2-port RX fiber at site C with the 11-slot 1-port RX fiber, the BC and CD main fibers were cut again, and the services was normal;
Root cause
The 11-slot 2-port RX optical fiber and the 11-slot 1-port RX optical fiber mandarin duck at site C cause the linear multiplex section to fail.
Solution
After swapping the 11-slot 2-port RX fiber with 11-slot 1-port RX fiber at site C, the BC and CD main fibers were disconnected again, and the services was normal.
Suggestions
After the linear multiplex section is switched, the service part is unavailable. Focus on checking whether the backup channel line and the cross-over board are faulty, whether the logical connection fiber and the physical connection fiber are consistent, and whether the protection group parameters are correct; you can select the unused VC4 channel to configure the 2M service test when positioning, facilitate services loopback positioning.
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