How to Locate Extension Subrack Cable Faults

Description of phenomenon:

OSN3500supports with expansion subrack, when the cable of expansion subrack fails, the crossover board of main subrack will reportBUS_ERRalarm. So how to determine which cable is faulty?

Cause analysis:

There are four cables between the main subframe and the expansion subframe of theOSN3500, and when the cable fails, you need to locate which cable is in trouble, so that you can easily replace the cable in a targeted manner.

Processing:

1、How to determine whether the expansion subrack cable problem causes the master subrack cross board to reportBUS_ERR?

Whenthe PARA[0]ofBUS_ERRis0x12, it means that there is a problem with the bus sent from the expansion subrack, and at this time, ifthe BIT[2]ofPARA[2]= 1, it can generally be determined that there is a problem with the cable of the expansion subrack, and at this time, PARA[2]is often0x04or0x06, for example:

131396249 9 BUS_ERR MJ end 2006-11-1 23:47:30 2006-11-1 23:47:36 0x12 0x02 0x04 0x01 0xff

At this time, this is generally accompanied byanHSC_UNAVAILalarm withPARA[0]of0x04.

131359349 9 HSC_UNAVAIL MJ end 2006-9-17 11:48:28 2006-9-17 11:49:51 0x04 0x01 0x09 0xff 0xff

2.After identifying the problem as a cable fault, how do I localize the fault to a specific cable?

In order to determine exactly which cable has failed, then new data needs to be collected.

(1) Query the first bus status

:optp:9,0,77,1,d,51,2,2,22,1; // 9means the board number,if queryingboard10, please change toa

Explanation of result: If the last two parameters of the returned result are00 00, it means there is no alarm and the bus status is normal, all other values mean there is alarm.

(2) Query clock asynchronous status

:optp:9,0,77,1,d,51,a,0,12,1; // 9means board number,if queryingboard number10, please change toa.

Result Note: If the last parameter of the returned result is8*, such as80, it means asynchronous, otherwise it is all synchronous.

(3) Query the second bus status

:optp:9,0,77,1,d,51,2,2,26,1; // 9means board number,if queryingboard number10, please change toa

Explanation of result: If the last two parameters of the returned result are00 00, it means there is no alarm and the bus status is normal, all other values mean there is alarm.

(4) Query clock asynchronous status

:optp:9,0,77,1,d,51,a,0,12,1; // 9means board number,if queryingboard10, please change toa.

Result Note: If the last parameter of the returned result is8*, such as80, it means asynchronous, otherwise it is all synchronous.

(5) Query the currently selecteddbheader anddbheader state

:optp:9,0,77,1,d,51,a,0,50,3; // 9means board number,if queryingboard number10, please change toa

Explanation of the result: the4thand5thparametersof the returned resultform a numberC.BIT[0]ofCindicatesthe selection control ofthe firstDS90CP22, when its value is0, it indicates the selection ofthe service ofthe expansion subrack lead boardA, and when its value is1, it indicates the selection ofthe service ofthe expansion subrack lead boardB;BIT[1]ofCindicatesthe selection control ofthe secondDS90CP22, when its value is0, itindicatesthe selection of theexpansion subrack leadboardB;BIT[1]ofCindicatesthe selection control of thesecondDS90CP22, when it value is 0 ,itindicates the selection of theexpansion subracklead boardA, andwhen it value is 0 , it indicatestheselectionoftheexpansion subrack leadboardB;Cis 0indicates thatthe service ofextended subrack lead boardAis selected, and when its value is1indicates that theservice ofextended subrack lead boardBis selected;BIT[2]ofCindicatesthe number of DB header switching times; otherBITsare not defined.

Note:XCE#60is theAlead board, connected tothe lower ports ofUXCSBs9and10;XCE#59is theBlead board, connected tothe upper ports ofUXCSBs9and10, which may not be quite in line with the custom.In addition,the BUS_ERRalarm is only reported if the query has an alarm on the current bus and the current clock is not asynchronous; if the clock is asynchronous,the BUS_ERRalarm is not reported regardless of whether there is an alarm on the bus or not;DBheader switching can also bring abouta B1error code.

BUS_ERRdue to expansion subrack cable faultscan be sporadic, depending on the synchronous or asynchronous state of the clock. Therefore,by collecting the above datawhenBUS_ERRoccurs and analyzingthe DBheaderselected when the clock is synchronous and an alarm exists on the corresponding bus, the fault can be localized to a specific cable. Please see the attached file for a more detailed data acquisition script and example analysis.

Attachment: Extended Subrack Cable Fault Analysis Example

BUS_ERR and HSC_UNAVAIL are reported on cross board 10 ofa set ofOSN3500with expansion subrackswith the following alarm parameters:

150370 10 BUS_ERR MJ start 2006-2-21 20:35:51 None 0x12 0x02 0x04 0x02 0xff

150374 10 HSC_UNAVAIL MJ start 2006-2-21 20:39:39 None 0x04 0x01 0x0a 0xff 0xff

PARA[0]ofHSC_UNAVAILis0x04, which indicates that it iscausedbyBUS_ERR.PARA[0]=0x12ofBUS_ERRindicates thatthereis a problem with the bus sent by theexpansionsubrack, andPARA[1]=0x02further indicates that there is a problem withthesecond bus.subrack cable fault;PARA[3]=0x02indicates thatBUS_ERRis detected by two cross-board handshakes.Please refer to the related case for the alarm parameter analysis ofBUS_ERR.

Therefore, according tothe alarm parameter of BUS_ERR , it can be judged that there is a problem with the cable of the expansion subrack, but which one is faulty? This requires the collection of further data analysis.

Query the first bus status

:optp:a,0,77,1,d,51,2,2,22,1

Optp cmd : 0d51

02 02 22 00 00

Total records :1

The result shows that the first bus is fine.

Query clock status

:optp:a,0,77,1,d,51,a,0,12,1

Optp cmd : 0d51

0a 00 12 00 00

Total records :1

Results indicate clock synchronization

Queries the status of the second bus:

:optp:a,0,77,1,d,51,2,2,26,1

Optp cmd : 0d51

02 02 26 00 04

Total records :1

The result shows that the second bus is abnormal withan alarm withparameter0x04, indicating the presence of aB1error.

Query the clock state at this time

:optp:a,0,77,1,d,51,a,0,12,1

Optp cmd : 0d51

0a 00 12 00 00

Total records :1

The result shows that the clocks are also in a synchronized state, soBUS_ERRwill be generatedwhen there is an alarm on the bus.This further clarifiesthat BUS_ERRis caused by a cable fault.

Query the currentDBheader to determine exactly which cable has failed

:optp:a,0,77,1,d,51,a,0,50,3

Optp cmd : 0d51

0a 00 50 00 03 00 01 00 01

Total records :1

The 4thand5thparametersof the returned resultcombine to0x03, which is represented in binary as11, i.e.,boththe firstDS90CP22and the secondDS90CP22are in thebusiness ofselecting the Extended Subframe Lead BoardB, whichis theXCEboard#59, whichisconnected tothe upper ports of theUXCSBs#9and#10via cables.Considering thatBUS_ERRis onlyreported on board#10,the connecting cable betweenboard #10 andboard #59needs to be replaced. After the replacement, the alarm disappeared.

The related technical information in this chapter and the troubleshooting process of SDH equipment are collected and organized by Shenzhen Optical Transmission Network Technology Co. Our company specializes in the sale of Huawei SDH optical transmission equipment, SDH transmission equipment.