Fiber carrier reported works on fiber, causing protection switching in a MSP ring. Fiber works were in DWDM network, carrying links for local SDH network.
When restoring fiber, continuous fiber events happened, causing protection switching between OSN 3500 A and OSN3500 B, due to R_LOF alarms. The R_LOF
alarms were reported every 5 to 15 seconds in line board (SLQ16 east side).
During R_LOF events, continuous MS_APS_INDI_EX alarms were reported in OSN 3500 A, and during these events, the services along the ring were affected,
approximately every 5 to 15 seconds.
1. In the ring, several and continuous fiber events (such as R_LOF) are reported.
2. Check the Abnormal events in T2000. If the is a Protection switching events are reported continuously, it could indicate that MSP protocol may have a problem.
1. Verify MSP parameters for associated ring
2. Check the status of MSP protocol in NE properties
3. If protocol status is “unknown”, delete and create protection group.
4. If MS_APS_INDI_EXC alarms are still reporting, check if switching trigger (R_LOF) is being reported in line board (SLQ16 east side, for example). In this case,
perform hard reset to the opposite line board (SLQ16 west side, for this example).
5. To analyze K1 events run :cfg-get-rmsevent command
Due to the continuous fiber events, OSN 3500 A could not process the K1 events properly. Line board (SLQ16 west side) did not send and received the K bytes,
causing service affectation.
When several triggers conditions are reported in MSP ring, do the following:
1. Shut down the laser in the affected path, to avoid several events that may cause saturation in the protocol processing.
2. If the protocol remains unstable, manually force the MSP protocol to protection in the affected path.
3. If the protocol remains unstable, perform hard reset to cross-connect and line boards.