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The OptiX OSN Reports an SYNC_F_M_SWITCH Alarm Abnormally

Publication Date:  2012-07-25 Views:  34 Downloads:  0
Issue Description
A customer's OptiX OSN 7500 network reports a SYNC_F_M_SWITCH alarm. Querying the Priority Table for System Clock Sources with the T2000 shows no clock source switching. The customer says there is no external clock source switching. The alarms and the parameters are shown below. 
Alarm Information
72278 9 SYNC_F_M_SWITCH IG start 2007-10-31 13:41:11 None 0xf1 0x01 0x02 0xff 0xff
72281 10 SYNC_F_M_SWITCH IG start 2007-10-31 13:41:12 None 0xf1 0x01 0x02 0xff 0xff
72282 10 SYNC_F_M_SWITCH IG start 2007-10-31 13:41:20 None 0xf1 0x01 0x03 0xff 0xff
72283 9 SYNC_F_M_SWITCH IG start 2007-10-31 13:41:21 None 0xf1 0x01 0x03 0xff 0xff 
Handling Process
Query once again the Output Priority Table for the First Phase-Lock Source of External Clocks and the Output Priority Table for the Second Phase-Lock Source of External Clocks. The switching status is displayed. The information gotten from the cross black box shows that a switching command was issued. The switching can be done even if there is only one internal clock source in the priority table.  
Root Cause
SYNC_F_M_SWITCH stands for clock source forced/manual switching alarm. The switching occurs usually when the NE software issues a forced/manual switching command.
Why does not querying the Priority Table for System Clock Sources return the status? Answering this question requires some knowledge about the alarm parameters.
Parameters 1 and 2 indicate the switched clock sources (0xf1 and 0x01 in this case, which are internal clock sources). Parameter 3 indicates the priority table concerning the switching.
The T2000 supports three priority tables (see the attachment to this case) that are Priority Table for System Clock Sources, Output Priority Table for the First Phase-Lock Source of External Clocks and Output Priority Table for the Second Phase-Lock Source of External Clocks.
Parameter 3 as 1 refers to the Priority Table for System Clock Sources.
Parameter 3 as 2 refers to the Output Priority Table for the First Phase-Lock Source of External Clocks.
Parameter 3 as 1 refers to the Output Priority Table for the Second Phase-Lock Source of External Clocks.
In this case, parameter 3 values 2 and 3. The customer apparently queries a wrong priority table. To check the switching status, one should query the Output Priority Table for the First Phase-Lock Source of External Clocks and the Output Priority Table for the Second Phase-Lock Source of External Clocks. 
Suggestions
 It is necessary to understand the meaning of the parameters of the alarm reported by the device.  

END