Solution : https://service.sap.com/sap/support/notes/657995 (SAP Service marketplace login required)
Key words : 
\oracle\<sid>\saptrace\background\<sid>alrt, found - checking database messages, br975w alert file <drv>, oracle alert log, alert_<sid>, symptom brconnect -, check reports, windows platform, br tools 6, downloading patches
Related Notes : 
       
| 12741 | Current versions of BR*Tools and SAPDBA |