The alarm of _R_LOF_ in OSN3500 happen incorrectly when the fiber is recovered

【Problem Summary】Pakistan CMPAK--"Pakistan CMPAK "3001Sha-3013.There are some Huawei SDH equipments issues."" 【Problem Details】The service cannot be revered automatically when the customer fixed the fibers that had been broken. SL64 board of 7500 equipment on Site A report alarm of R_LOF unconventionally, and there were no alarm of 13LSX of 6800 equipment. The service could be recovered when we take the FEC mode of 13LSX to change from AFEC to FEC on site A ,then back to AFEC.The figure below shows the affected line on the network, SL64 board reported “R_LOF”alarm on site SHA:

 The status is normal when the fiber is broken.

 The status is abnormal when the fiber is fixed.

The reason of the “R_LOF” in N4SL64 board reported as below:

² Reason 1：A pair of board has difficult rate of the service------cleared: the 13LSX and N4SL64 board have same service’s rate and the service configuration is STM-64(set in 13LSX board) and the remote site was not changed.

² Reason 2：The problem of fiber line------cleared: the problem is not caused by WDM fiber broken but the recovery of Huawei WDM fiber, the 13LSX board is OK (no alarms) when the fiber was recovered. The connection between 13LSX and SL64 is not changed.

² Reason 3：The receiving end on the board has some problem in SL64 board, cause the frame of signals lost ------waiting be checked, we should check the N4SL64 board.

² Reason 4：The transmission end on remote board has some problem, cause the frame of signals lost------waiting be checked, we should check the clock and the frame signals of 13LSX board.

We replaced both 13LSX board and SSN4SL64 board at site A in current network. After this step, problem didn’t reoccur upon testing, moreover, the link is working normally up till now. According to the problem analysis and steps performed during problem troubleshooting, hardware problem is suspected in either LSX or N4SL64 boards in the equipments. We found the XFP module in SL64 board has a problem after R&D analyze the 13LSX and N4SL64 board in lab. the XFP module don't deal with the signals correctly with low probability and caused the alarm of "R_LOF" reported in N4SL64 board when the fiber is recovering instantaneously. The problem was recurred in R&D's lab.the problem is reported with low probability as below: 1. the fiber from "broken" to "normal" 2. The input of optical power is about -8~-11 dBm; 3. The type of XFPis HXFP8441(03030JCB) or HXFP8240(34060322) 4. The bug in XFP module is caused by the quality of signals, which can be fixed by software upgrade.

【Resolution Summary】the XFP module in SL64 board is a problem and can be fixed by software upgrade 【Resolution Details】The new XFP will be been fixed in Q1,2014, we can replace the problem XFP with new one. And we also upgrade the version of OSN equipment to V2R12C01spc103 or R10c03 newest version(Both versions will be released on Oct, 2014) in the future.

Technical Case: Optical Network

Optical network within Huawei WDM, Huawei NG-SDH, T2000 double system structure sometimes get some emergency situations, for example: service trail abnormally, network traffic abnormal, device exceptional warning, packet forwarding failure, board abnormal, interface abnormal and etc.

1.1 The detailed network information as follows, Optical network comprises one NG-SDH ASON network and one Backbone WDM network. NG-SDH ASON network is made up of OSN 7500 equipments, and Backbone WDM network is made up of 1600G equipments, the NG-SDH network is constructed upon 1600G Backbone WDM network, NG-SDH ASON network carried customer diamond Service, such as detail network information in the attachment.

2.1.1.WDM Backbone network topology
WDM Backbone networks are made up of 1600G equipment DCN Design of WDM Backbone networks detail information.

2.1.2 NG-OSN ASON network topology
NG-SDH ASON Networks is made up of OSN7500 equipment detail main network topology framework as mentioned.

3.1 Carried Services Analysis
NG-SDH ASON networks carried by WDM Backbone networks, WDM Backbone networks according to different service requirement up and down different wavelength service in the propriety section such as carried networks for customer demand, NG-SDH ASON networks carried ASON service, Currently Configuration all ASON service LSA Level is diamond service on the ASON networks.

3.1.1 Service and Running Status Analysis
During eleven months working and network running for networks, Currently WDM Backbone networks running status is stability, sometimes due to customer provided link fiber frequently by cut would affect WDM Backbone networks stability, it’s our maintenance team come up against an important problem in NOC, at the same time our team very important job supervise customer to solved in time for link fiber cut bring WDM Backbone networks break off.
Currently NG-SDH ASON networks running status is stability, Customer configuration total LSA service is diamond service，from inspector return result view service running is stability and normal, but Customer Choice Revertive parameter when configuration diamond service on the ASON networks, when active service is break off re-route to another trail, due to customer link-fiber cut long time can’t recover , change or modify this service on the NMS by configuration Revertive Parameter LAS service will become disperse service would affect ASON networks running stability and efficiency ,advice change Revertive LAS service to NON-Revertive services for customer.

3.1.2 NMS running status Analysis
NMS type is use T2000, According with every days checking list proved NMS T2000 running status is normal and stability, Currently project process addition many new WDM 1600G and NG-OSN 7500 NE according with originally design divide WDM and OSN ASON to two single NMS Server for monitor, now doing this plan, if completed it NMS running status would be enhance.
3.2 Detailed Devices Information
Optical networks Devices include OTM, OADM, OLA of WDM and OSN7500 of NG-SDH ASON networks, hardware and software configuration, both WDM and ASON network detailed devices information view as follows.

3.2.1 Basic device information
Optical networks basic device information includes type of Huawei WDM and Huawei NG-SDH devices, site configuration information and so on detail information in the attachment.
3.2.2 Device configuration
WDM and NG-Huawei OSN networks Device configuration information including NE board version and NE information, and ASON service detail information such as attachment as follows:

3.3 Risks Analysis
Describe all the risks that have been found during network routing inspection, network evaluation and troubleshooting process; and the possible workaround and solutions.
3.3.1 Network Risk Analysis
During eleven month maintenance in the NOC for WDM and NG-OSN networks, we already mastery about WDM and ASON networks running status, currently network risk mostly focus on item as follow:
1. Customer provided link fiber frequently by cut would affect WDM Backbone networks stability, it’s our maintenance team come up against an important problem in NOC, at the same time our team very important job supervise customer to solved in time for link fiber cut bring WDM Backbone networks break off.
2. Customer Choice Revertive parameter when configuration diamond service on the ASON networks, when active service is break off re-route to another trail, due to customer link-fiber cut long time can’t recover , change or modify this service on the NMS by configuration Revertive Parameter LAS service will become disperse service

would affect ASON networks running stability and efficiency.
3. Due to upload NE of WDM and NG-SDH is new created; software version of board of NE is not match with design.

4 Emergency Solution
When serious problems such as service interruption occur on equipment of WDM and NG-SDG ASON networks, emergency solution provides for the equipment maintenance personnel to locate and remove the fault quickly, Focus on service recovery, divide issues to different scenes and give detailed emergency solutions,To ensure the stable running of the optical transmission system and reduce the emergency accident to the minimum extent. The operation and maintenance to long-term also important project as optical network, summarize the history problems happened, so as to improve the critical problem response process, these type of problem should be enhance Huawei optix network maintenance and emergency response implementation guide confidentiality level.