ONS 15454 LOS-O minor alarm problem

Answered Question
Aug 23rd, 2010
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Hello everybody, wish you a nice day!


I have 2 ONS 15454 at 2 site in linear mode.


ONS 1 (side A) -------- line 1 -------- ONS 2 (side B)

ONS 1 (side B) -------- line 2 -------- ONS 2 (side A)


3 days ago, I got the LOS-O alarm. I have followed the instruct from troubleshooting guide but could not clear this alarm.

Here is the site view:

v\:* {behavior:url(#default#VML);} o\:* {behavior:url(#default#VML);} w\:* {behavior:url(#default#VML);} .shape {behavior:url(#default#VML);} /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:10.0pt; font-family:"Calibri","sans-serif"; mso-bidi-font-family:"Times New Roman";}

v\:* {behavior:url(#default#VML);} o\:* {behavior:url(#default#VML);} w\:* {behavior:url(#default#VML);} .shape {behavior:url(#default#VML);} /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:10.0pt; font-family:"Calibri","sans-serif"; mso-bidi-font-family:"Times New Roman";} site view.jpg

(In this firgure, dont care about side A, my trunk line is cut . The problem is on side B, it pops some minor alarm but the connection is still ok)


ALARM:


You can see that there are: SPANLEN-OUT-OF-RANGE and LOS-O. The problem is the power on line RX on OSC-CSM card is below the configured threshold, right? I have monitored the power and the value is -19.5 dbm.

Then I go to Provisioning --> WDM-ANS --> side B --> Rx --> Threshold.OSC LOS is imported as -23.5 dbm.


I also checked the span loss, the measured spanloss is 15.2 (resolution 1.5). It is between the Min exp span loss (15) and Max exp span loss (17).


So what is the problem, please help me to clear this alarm. Thank you very much.

Correct Answer by Alexei Kiritchenko about 6 years 9 months ago

/* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;}

You are right. the alarm is shown as the power is below the threshold.

If we have OSC LOS threshold set to -23.5 and the total Rx power is Rx power is about -23.5 (on the 40 km span) then we definitely below the threshold as we need to subtract the payload power from the total to get OSC.


Average loss on a fiber is 0.3dB per km, hence the expected loss on 40km would be around 12dB. I doubt the OS Tx power on the remote end is -11dBm (-23 + 12) so most likely that is the fiber/connector issue.


Swap Line Rx and Tx fibers on both switches on OSC-CSM card to verify if the problem follows the fiber or stay with the cards.


Regards,

Alex.

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hiepnguyenho Mon, 08/23/2010 - 20:15
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/PS:


When I sit on node 1, I can measure span loss. But when I site on  node 2, I can not. So is there any big problem here? Thank you.

Alexei Kiritchenko Wed, 08/25/2010 - 07:41
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  • Cisco Employee,

may you attach following screenshots?

OSC-CSM --> Provisioining-> Optical Line -> Parameters

OSC-CSM --> Provisioining-> Optical Line -> Optic Thresholds (Chose Alam and click Refresh)

hiepnguyenho Thu, 08/26/2010 - 18:53
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Hi Alexei,


I'm sorry for late. I'm being on bussiness trip so I can not onsite at my customer. But when I showed Parameters and Optic threshold tab on OSC card, the result is like this:

- Parameter: the Rx power is about -23.5 (on the 40 km span)

- Optic threshold: the value on Line Rx and Line Tx is N/A.


Note that the Rx power on side B (the other side of this node) is -12 dbm. So may be the problem is very low Rx power? Thank you very much.

Correct Answer
Alexei Kiritchenko Thu, 08/26/2010 - 21:15
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  • Cisco Employee,

/* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;}

You are right. the alarm is shown as the power is below the threshold.

If we have OSC LOS threshold set to -23.5 and the total Rx power is Rx power is about -23.5 (on the 40 km span) then we definitely below the threshold as we need to subtract the payload power from the total to get OSC.


Average loss on a fiber is 0.3dB per km, hence the expected loss on 40km would be around 12dB. I doubt the OS Tx power on the remote end is -11dBm (-23 + 12) so most likely that is the fiber/connector issue.


Swap Line Rx and Tx fibers on both switches on OSC-CSM card to verify if the problem follows the fiber or stay with the cards.


Regards,

Alex.

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