Message Oracle TNS-12547 - TNS: lost contact

ERRORTNS: lost contact
CAUSEPartner has unexpectedly gone away, usually during process startup.
ACTIONInvestigate partner application for abnormal termination. On an Interchange, this can happen if the machine is overloaded.

954896ORA-12547 connecting to sqlplus / as sysdba on AIX 5L
505630Composite SAP Note ORA-12547