Looking for trouble shooting help -Connections being dropped from app.

Question

I need a little help in hunting down the source of a problem. We have Oracle 10gR2 (10.2.0.1) running on Solaris 10. The web application is based on WEBLOGIC on another server also running Solaris 10 with a new firewall in between. When started, the application will get 176 connections to the database. Over time, still working on how long, the connections get dropped. The profile they app is connecting to is for unlimited connections and connection time. I do not have an setting to disconnect after idle for x minutes. Even the listener spawned processes die. Other applications from other machines also have problems if idle for a period of time, SQLDeveloper, SQLPlus, TOAD, SQLNAVIGATOR.
We are trying to hunt down the source of the problem but are at a loss. I have checked and verified that the oracle instance does not have a parameter set to kill idle connections for the users the apps are connecting as. The sys admin says there are no unix parameters he knows about on either solaris box that is killing connections and that the firewall settings should not be killing them.
A duplicate environment running all the same versions of software work fine, the only differences between the two is the box and operating system, Sun V120 w/Solaris 8 vs. Sun V40Z w/Solaris 10.
This system goes live in two weeks so we are trying to get this figured out soon. Any hints on where to look or has any one else had similar problems?
thanks

Answer 1

listener.ora on Oracle server machine:
# listener.ora Network Configuration File: /u01/app/oracle/product/10.2/db_1/network/admin/listener.ora
# Generated by Oracle configuration tools.
SID_LIST_LISTENER =
(SID_LIST =
(SID_DESC =
(SID_NAME = PLSExtProc)
(ORACLE_HOME = /u01/app/oracle/product/10.2/db_1)
(PROGRAM = extproc)
LISTENER =
(DESCRIPTION_LIST =
(DESCRIPTION =
(ADDRESS = (PROTOCOL = TCP)(HOST = ng-db01)(PORT = 1521))
(ADDRESS = (PROTOCOL = IPC)(KEY = EXTPROC0))
Weblogic machine is not useing a client so has no sqlnet.ora file on it. Others having problem:
# sqlnet.ora Network Configuration File: C:\oracle\product\10.2.0\db_1\network\admin\sqlnet.ora
# Generated by Oracle configuration tools.
# This file is actually generated by netca. But if customers choose to
# install "Software Only", this file wont exist and without the native
# authentication, they will not be able to connect to the database on NT.
SQLNET.AUTHENTICATION_SERVICES= (NTS)
NAMES.DIRECTORY_PATH= (TNSNAMES, EZCONNECT)