How to handle 'SDH/SONET LP Trace Identifier Mismatch' Alarm [ALM-21259] Highlighted

Hello Community Members,

Today, I will share with you the handling procedure of ALM-21259 SDH/SONET LP Trace Identifier Mismatch Alarm.

Problem:

We had observed that SDH/SONET LP Trace Identifier Mismatch alarms were reported on multiple BSCs, one example of alarm can be seen below:

About J2 Byte:

Path overhead byte Read more at  http://acronymsandslang.com/definition/7240330/J2-meaning.html

Path overhead byte Read more at  http://acronymsandslang.com/definition/7240330/J2-meaning.html

J2 byte is a low order path trace identifier. This byte is the low order path access point identifier that is negotiated and repeatedly transmitted between the RX end and TX end. On receiving J2, the RX end determines whether the RX end and the TX end are in continuous connection state in the low order path.

Possible Cause:

SDH/SONET LP Trace Identifier Mismatch alarm is generated when the J2 byte received by the system is inconsistent with the expected one.The possible cause of this alarm is due to incorrect configuration of the J2 byte format.

Alarm Attribute:

This alarm is reported on active and standby port OIUa / OIUb board. For the POUc board this alarm is reported on the active port when the backplane version of subrack is VER.A or VER.B and if the backplane version of subrack is VER.C, it is reported on active board.

Note: OIU board is a single port board while POUc board is having 4 ports.

Alarm Impact:

1. We will first check the configuration of the optical port:

1. 
   

   1. Run LST COPTLNK to query the J2 byte (note the J2 Transmit Value that are set at the local end.)

      
      

b. Run DSP OPTOH (with DSPFORMAT set to Character_String) to query the J2 byte which is actually received by the local end

c. COMPARE both values that are obtained with the help of commands in step 1a and 1b (in RED box). If both values are same, the configuration is correct and vice versa.

We can see that both the received the value actually received by the local end is inconsistent with the configured one. That is why this alarm is appearing.

Solution

SET the J2 byte value same at local end and at peer end.

Note: Board reset is required.The change of the optical port mode takes effect only after the corresponding interface board is reset. In addition, the change of the optical port mode applies to all optical ports on one board.

Thank you for reading. You're welcome to feedback at the comment box below about this post or leave a provate message !