ORA-12170: TNS:Connect timeout occurred, TNS-12535: TNS:operation timed out

Hi!

I have two hosts running on "Windows Server 2003". One is the PCO199, where the Oracle Application Server (OAS) & the Oracle Identity Manager (OIM), both 10g Release 2, are running. Both have two instances: one for a development environment, the other for a test environment. So, on PCO199, there are four (4) ORACLE_HOME directories.

On a second host running on the same OS, called PCO206, there are currently three databases running. 'Elba' & 'ElbaTst' constitute the test databases; the former has the old data status. I imported to ElbaTst the newest application data (from a DMP file). The third database (server instance also) is called ElbaDev & is the database for the development environment. (Elba will be removed soon so that ElbaTst is the test database).

On both machines, I can open the SQL*Plus & access the databases that are running there locally. That means that:
+ PCO199:
=========================================================================
SQL> CONNECT system/<pwd>@OraMDR
Connected.
SQL> CONNECT system/<pwd>@OrMDRdev
Connected.
_________________________________________________________________________


+ On PCO206:
=========================================================================
SQL> CONNECT system/<pwd>@Elba
Connected.
SQL> CONNECT system/<pwd>@ElbaDev
Connected.
SQL> CONNECT system/<pwd>@ElbaTst
Connected.
_________________________________________________________________________

But on both machines, I cannot access the databases that are running on the other host:
- PCO199:
=========================================================================
SQL> CONNECT system/<pwd>@Elba
ERROR:
ORA-12170: TNS:Connect timeout occurred


Warning: You are no longer connected to ORACLE.
SQL> CONNECT system/<pwd>@ElbaDev
ERROR:
ORA-12170: TNS:Connect timeout occurred


Warning: You are no longer connected to ORACLE.
SQL> CONNECT system/<pwd>@ElbaTst
ERROR:
ORA-12170: TNS:Connect timeout occurred


Warning: You are no longer connected to ORACLE.
_________________________________________________________________________


- On PCO206:
=========================================================================

SQL> CONNECT system/<pwd>@OraMDR
ERROR:
ORA-12170: TNS:Connect timeout occurred


Warning: You are no longer connected to ORACLE.
SQL> CONNECT system/<pwd>@OrMDRdev
ERROR:
ORA-12170: TNS:Connect timeout occurred
_________________________________________________________________________

All this STUFFF run before I left for another project, but now it makes problems. :@@@

But I hope that you will give me the right hints so that the databases on both hosts can connect to each other again.

Here are some results:
+ PCO199:
=========================================================================
Microsoft Windows [Version 5.2.3790]
(C) Copyright 1985-2003 Microsoft Corp.

C:\WINDOWS>tnsping OraMDR

TNS Ping Utility for 32-bit Windows: Version 10.1.0.4.2 - Production on 21-SEP-2
007 20:26:22

Copyright (c) 1997, 2003, Oracle.  All rights reserved.

Used parameter files:
C:\ProgramFiles\Oracle\network\admin\sqlnet.ora


Used TNSNAMES adapter to resolve the alias
Attempting to contact (DESCRIPTION = (ADDRESS = (PROTOCOL = TCP)(HOST = pco199.i
nf.beko.local)(PORT = 1521)) (CONNECT_DATA = (SERVER = DEDICATED) (SERVICE_NAME
= OraMDR)))
OK (10 msec)
_________________________________________________________________________

- PCO199:
=========================================================================
C:\WINDOWS>tnsping Elba

TNS Ping Utility for 32-bit Windows: Version 10.1.0.4.2 - Production on 21-SEP-2
007 20:26:28

Copyright (c) 1997, 2003, Oracle.  All rights reserved.

Used parameter files:
C:\ProgramFiles\Oracle\network\admin\sqlnet.ora


Used TNSNAMES adapter to resolve the alias
Attempting to contact (DESCRIPTION = (ADDRESS = (PROTOCOL = TCP)(HOST = pco206.i
nf.beko.local)(PORT = 1521)) (CONNECT_DATA = (SERVER = DEDICATED) (SERVICE_NAME
= Elba)))
TNS-12535: TNS:operation timed out

C:\WINDOWS>
_________________________________________________________________________

On the other machine:
+ PCO206:
=========================================================================
C:\Documents and Settings\LocAdm\My Documents>tnsping Elba

TNS Ping Utility for 32-bit Windows: Version 10.2.0.1.0 - Production on 21-SEP-2
007 20:29:54

Copyright (c) 1997, 2005, Oracle.  All rights reserved.

Used parameter files:
C:\ProgramFiles\oracle\product\10.2.0\db_3\network\admin\sqlnet.ora


Used TNSNAMES adapter to resolve the alias
Attempting to contact (DESCRIPTION = (ADDRESS = (PROTOCOL = TCP)(HOST = pco206.i
nf.beko.local)(PORT = 1523)) (CONNECT_DATA = (SERVER = DEDICATED) (SERVICE_NAME
= Elba)))
OK (50 msec)

C:\Documents and Settings\LocAdm\My Documents>
_________________________________________________________________________

- PCO206:
=========================================================================
C:\Documents and Settings\LocAdm\My Documents>tnsping OraMDR

TNS Ping Utility for 32-bit Windows: Version 10.2.0.1.0 - Production on 21-SEP-2
007 20:22:27

Copyright (c) 1997, 2005, Oracle.  All rights reserved.

Used parameter files:
C:\ProgramFiles\oracle\product\10.2.0\db_3\network\admin\sqlnet.ora


Used TNSNAMES adapter to resolve the alias
Attempting to contact (DESCRIPTION = (ADDRESS = (PROTOCOL = TCP)(HOST = pco199.i
nf.beko.local)(PORT = 1523)) (CONNECT_DATA = (SERVER = DEDICATED) (SERVICE_NAME
= OraMDR)))
TNS-12535: TNS:operation timed out

C:\Documents and Settings\LocAdm\My Documents>
_________________________________________________________________________