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RPR function could not activate due to improper insertion of EGR2 board when fibre broke in the ring

Publication Date:  2012-07-25 Views:  183 Downloads:  0

Issue Description

Below diagram shows the SDH ring , where Optix OSN 1500B has been installed at different four location
Connection diagram

Some details of 4 NEs are given below.
No. NE Name NE Type version Subrack Type NE ID Gateway ip address
1 FM-Pulchowk OptiX OSN 1500 V1R3C02B032SP03 Subrack Type B 918 Non-Gateway
2 KRISHNA tOWER OptiX OSN 1500 V1R3C02B032SP03 Subrack Type B 916 Non-Gateway
3 SATDOBATO OptiX OSN 1500 V1R3C02B032SP03 Subrack Type B 914 Non-Gateway
4 SNPL OptiX OSN 1500 V1R3C02B032SP03 Subrack Type B 912 IP Gateway (gateway)

Service from EGR2 board had been interrupted at Krishna Tower when fiber cable had broken between Krishna Tower and Satdobato.

Alarm Information

BD_STATUS alarm reported for the slot11 SSN2EGR2 board of FM pulchowk on date 2011-11-09.

  757979      13    T_ALOS                MJ          start       2011-7-13 15:57:26   None                 0x01   0x00   0x29   0xff   0xff  
  823488      13    T_ALOS                MJ          start       2011-9-19 15:39:18   None                 0x01   0x00   0x2a   0xff   0xff  
  868502      11    BD_STATUS           MJ          start       2011-11-9 13:42:8    None                  0xff     0xff   0xff   0xff    0xff  
  876337      13    T_ALOS                MJ          start       2011-11-17 13:36:13  None                 0x01   0x00   0x0e   0xff   0xff  
  876338      13    T_ALOS                MJ          start       2011-11-17 13:36:14  None                 0x01   0x00   0x0d   0xff   0xff  
  891635      13    T_ALOS                MJ          start       2011-11-30 16:5:8    None                 0x01   0x00   0x09   0xff   0xff  


Handling Process

Solution has been taken already for this problem on date 2011-12-02 by giving bypass from 4-SL16 to 5-SL16 at FM Pulchowk.

Root Cause

When EGR2 Board had been shifted at FM pulchowk on date 2011-11-09, but at that time service had not affected at Krishna Tower. Due to the RPR protection, it worked normally.

If there had service from FM Pulchowk EGR2 board to Pulchowk customer care, that would be affected but as per info from Ncell datacom team, service for Pulchowk customer care has not been taken after this date 2011-9-28 froM FM pulchowk.
Case 1: Krishna tower service from EGR2 had not interrupted on date 2011-11-09, although FM Pulchowk EGR2 board shifted .

We can see from below alarm notifcation that due to the failure of FM Pulchowk EGR2 Board, direction has been changed on date 2011-11-9.

Severity Name Alarm Source Location Info Generated Time Cleared Time
Minor RPR_PS_CHANGE KRISHNA tOWER 13-N2EGR2-RPR:1 9/11/2011 13:42 2/12/2011 16:37
Minor RPR_PS_CHANGE SNPL 13-N2EGR2-RPR:1 9/11/2011 13:42 2/12/2011 16:37
Case 2: Krishna tower service from EGR2 had interrupted on date 2011-12-02, when fiber had broken between Krishna Tower and Satdobato, EGR2 board shifted at FM Pulchowk.
It means EGR2 of FM Pulchowk is not working and fiber broken between Krishna Tower and Satdobato so this is root cause how service given by EGR2 of Krishna Tower had been interrupted.


Root cause of this problem has been found out,  due to EGR2 board had displaced at FM pulchowk. Due to this and another fiber broken, no RPR function became applied although it is working well. It can be suggested that either  from the site or from NMS, equipment should be inspect on daily basis.