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EOS interrupted 6 minutes due to error and LCAS issue

Publication Date:  2012-07-25 Views:  101 Downloads:  0
Issue Description
customer reported that several EoS services were automatic interrupted 6 minutes, and services were automatic up.
Alarm Information
The NE's faulty channel reported B3_SD_VC4, LCAS_TLCR, and LCAS_PLCR alarms.
Handling Process
1. Check the services conifgured,it is ok.
2. Checked for historical alarms and events of NE Source and Sink,the NE's faulty channel reported B3_SD_VC4, LCAS_TLCR, and LCAS_PLCR alarms.
3. Check the LCAS configure information, the WTR time for LCAS is 5 minutes.
4. Based on LCAS principles, Huawei confirmed that B3 bit errors caused H4 byte abnormalities, H4 byte abnormalities triggered LCAS alarms, and LCAS alarms resulted in LCAS service interruptions.
5. H4 bytes are used to carry control information on higher order channels, and K4 bytes are used to carry control information on lower order channels. The LCAS protocol runs based on the handshaking of control information from source and sink ends. If bytes carrying control information are impaired by bit errors, LCAS services are interrupted.

 
Root Cause

1.The services configured have some issue.

2.The path communication fails because the cross-connection is incorrect or other alarms are present.


Suggestions

1.Check optical fibers and ensure that optical paths are stable.

2.Change the BER threshold for B3_SD alarms from 10-6 to 10-7.

3.Set the WTR time for LCAS to a value less than 5 minutes (The default WTR time for LCAS is 5 minutes. ITU-T recommends a range from 5 minutes to 12 minutes).


END