创建测试脚本
通过在三个会话中同时执行test_login.sh脚本,模拟当数据库多个短连接情况性能

[oracle@xifenfei tmp]$ more test_login.sh
#!/bin/bash
echo "start login database `date`*********" >>/tmp/test_1.log
e=2000
for((i=1;i<=$e;i=i+1))
do
/tmp/login_oracle.sh
done
echo "end login database `date`*********" >>/tmp/test_1.log
[oracle@xifenfei tmp]$ more login_oracle.sh
#!/bin/bash
sqlplus chf/xifenfei@ORA11G_P<<XFF>/dev/null
select to_char(sysdate,'yyyy-mm-dd hh24:mi:ss') from dual;
exit
XFF
--ORA11G_P根据不同的测试情景指定不同名称

情况1:一个监听情况下

start login database Tue May  1 18:03:32 CST 2012*********
start login database Tue May  1 18:03:35 CST 2012*********
start login database Tue May  1 18:03:37 CST 2012*********
end login database Tue May  1 18:08:20 CST 2012*********
end login database Tue May  1 18:08:25 CST 2012*********
end login database Tue May  1 18:08:26 CST 2012*********
--计算2000个会话登录/查询/推出时间
4:48
4:40
4:49

情况2:三个监听,客户端配置tns负载均衡

--监听配置
LISTENER =
  (DESCRIPTION_LIST =
    (DESCRIPTION =
      (ADDRESS = (PROTOCOL = TCP)(HOST = 192.168.1.10)(PORT = 1521))
    )
  )
SID_LIST_LISTENER =
  (SID_LIST =
    (SID_DESC =
     (GLOBAL_DBNAME = ora11g)
     (ORACLE_HOME = /u01/oracle/oracle/product/11.2.0/db_1)
     (SID_NAME = ora11g)
    )
  )
ADR_BASE_LISTENER = /u01/oracle
LISTENER1 =
  (DESCRIPTION_LIST =
    (DESCRIPTION =
      (ADDRESS = (PROTOCOL = TCP)(HOST = 192.168.1.10)(PORT = 1522))
    )
  )
SID_LIST_LISTENER1 =
  (SID_LIST =
    (SID_DESC =
     (GLOBAL_DBNAME = ora11g)
     (ORACLE_HOME = /u01/oracle/oracle/product/11.2.0/db_1)
     (SID_NAME = ora11g)
    )
  )
ADR_BASE_LISTENER1 = /u01/oracle
LISTENER2 =
  (DESCRIPTION_LIST =
    (DESCRIPTION =
      (ADDRESS = (PROTOCOL = TCP)(HOST = 192.168.1.10)(PORT = 1523))
    )
  )
SID_LIST_LISTENER2 =
  (SID_LIST =
    (SID_DESC =
     (GLOBAL_DBNAME = ora11g)
     (ORACLE_HOME = /u01/oracle/oracle/product/11.2.0/db_1)
     (SID_NAME = ora11g)
    )
  )
ADR_BASE_LISTENER2 = /u01/oracle
--tns配置
ORA11G_M =
  (DESCRIPTION =
      (LOAD_BALANCE=ON)
      (FAILOVER=ON)
      (ADDRESS_LIST =
       (ADDRESS = (PROTOCOL = TCP)(HOST = 192.168.1.10)(PORT = 1521))
       (ADDRESS = (PROTOCOL = TCP)(HOST = 192.168.1.10)(PORT = 1522))
       (ADDRESS = (PROTOCOL = TCP)(HOST = 192.168.1.10)(PORT = 1523))
       (LOAD_BALANCE = yes)
    )
    (CONNECT_DATA =
     (SERVER=DEDICATED)
      (SERVICE_NAME = ora11g)
    )
  )
--测试结果
start login database Tue May  1 17:51:45 CST 2012*********
start login database Tue May  1 17:51:49 CST 2012*********
start login database Tue May  1 17:51:51 CST 2012*********
end login database Tue May  1 17:55:58 CST 2012*********
end login database Tue May  1 17:56:06 CST 2012*********
end login database Tue May  1 17:56:09 CST 2012*********
--计算2000个会话登录/查询/推出时间
4:13
4:17
4:18

情况2:使用常驻连接池DRCP(11g新特性)

--启动默认DRCP
SQL> exec dbms_connection_pool.start_pool();
PL/SQL procedure successfully completed.
--tns配置
ORA11G_P =
  (DESCRIPTION =
    (ADDRESS_LIST =
      (ADDRESS = (PROTOCOL = TCP)(HOST = 192.168.1.10)(PORT = 1521))
    )
    (CONNECT_DATA =
     (SERVER=POOLED)  --注意
      (SERVICE_NAME = ora11g)
    )
  )
--执行结果
start login database Tue May  1 18:19:58 CST 2012*********
start login database Tue May  1 18:20:01 CST 2012*********
start login database Tue May  1 18:20:03 CST 2012*********
end login database Tue May  1 18:23:16 CST 2012*********
end login database Tue May  1 18:23:19 CST 2012*********
end login database Tue May  1 18:23:21 CST 2012*********
--计算2000个会话登录/查询/推出时间
3:16
3:18
3:19

总结
如果在数据库短连接过程中发现监听是瓶颈的时候,可以考虑使用多个监听+tns 负载均衡,从一定程度上缓解监听瓶颈.如果是11g数据库可以考虑使用其心功能DRCP,从而很大程度上提高短连接过程中数据库的效率.因为DRCP还属于11g的新功能稳定性不知道如何?使用该功能前,请一定要做好相关测试工作.如有可能还是建议从应用层面尽可能的使用长连接,提高数据库会话效率.

发现监听进程监听8080和2100端口

--监听端口
[oracle@xifenfei ~]$ netstat -nap|grep tnslsnr
(Not all processes could be identified, non-owned process info
 will not be shown, you would have to be root to see it all.)
tcp        0      0 0.0.0.0:8080                0.0.0.0:*                   LISTEN      29866/tnslsnr
tcp        0      0 0.0.0.0:1521                0.0.0.0:*                   LISTEN      29866/tnslsnr
tcp        0      0 0.0.0.0:2100                0.0.0.0:*                   LISTEN      29866/tnslsnr
--进程名称
[oracle@xifenfei ~]$ ps -ef|grep 29866
oracle   29866     1  0 00:20 pts/0    00:00:00 /u01/oracle/9.2.0/db_1/bin/tnslsnr LISTENER -inherit

查看监听状态

[oracle@xifenfei ~]$ lsnrctl status
LSNRCTL for Linux: Version 9.2.0.4.0 - Production on 08-MAY-2012 00:26:50
Copyright (c) 1991, 2002, Oracle Corporation.  All rights reserved.
Connecting to (DESCRIPTION=(ADDRESS=(PROTOCOL=TCP)(HOST=xifenfei)(PORT=1521)))
STATUS of the LISTENER
------------------------
Alias                     LISTENER
Version                   TNSLSNR for Linux: Version 9.2.0.4.0 - Production
Start Date                08-MAY-2012 00:20:47
Uptime                    0 days 0 hr. 6 min. 3 sec
Trace Level               off
Security                  OFF
SNMP                      OFF
Listener Parameter File   /u01/oracle/9.2.0/db_1/network/admin/listener.ora
Listener Log File         /u01/oracle/9.2.0/db_1/network/log/listener.log
Listening Endpoints Summary...
  (DESCRIPTION=(ADDRESS=(PROTOCOL=tcp)(HOST=xifenfei)(PORT=1521)))
  (DESCRIPTION=(ADDRESS=(PROTOCOL=ipc)(KEY=EXTPROC)))
  (DESCRIPTION=(ADDRESS=(PROTOCOL=tcp)(HOST=xifenfei)(PORT=8080))(Presentation=HTTP)(Session=RAW))
  (DESCRIPTION=(ADDRESS=(PROTOCOL=tcp)(HOST=xifenfei)(PORT=2100))(Presentation=FTP)(Session=RAW))
Services Summary...
Service "PLSExtProc" has 1 instance(s).
  Instance "PLSExtProc", status UNKNOWN, has 1 handler(s) for this service...
Service "xffXDB" has 1 instance(s).
  Instance "xff", status READY, has 1 handler(s) for this service...
Service "xifenfei" has 2 instance(s).
  Instance "xff", status UNKNOWN, has 1 handler(s) for this service...
  Instance "xff", status READY, has 1 handler(s) for this service...
The command completed successfully
--从这里可以看出oracle的listener确实监听了8080和2100端口

查看listener.ora文件

[oracle@xifenfei ~]$ more /u01/oracle/9.2.0/db_1/network/admin/listener.ora
# LISTENER.ORA Network Configuration File: /u01/oracle/9.2.0/db_1/network/admin/listener.ora
# Generated by Oracle configuration tools.
LISTENER =
  (DESCRIPTION_LIST =
    (DESCRIPTION =
      (ADDRESS_LIST =
        (ADDRESS = (PROTOCOL = TCP)(HOST = xifenfei)(PORT = 1521))
      )
      (ADDRESS_LIST =
        (ADDRESS = (PROTOCOL = IPC)(KEY = EXTPROC))
      )
    )
  )
SID_LIST_LISTENER =
  (SID_LIST =
    (SID_DESC =
      (SID_NAME = PLSExtProc)
      (ORACLE_HOME = /u01/oracle/9.2.0/db_1)
      (PROGRAM = extproc)
    )
    (SID_DESC =
      (GLOBAL_DBNAME = xifenfei)
      (ORACLE_HOME = /u01/oracle/9.2.0/db_1)
      (SID_NAME = xff)
    )
  )
--从中确认未监听8080和2100端口,看来这两个端口是在动态注册监听的时候加入进去的.
--我们知道oracle的xdb组件可能会启用http和ftp功能,这两个功能可能会开启响应端口,我们分析xdb组件.

查看xdb组件是否工作正常

SQL> select
  2  comp_name, status, version from
  3  DBA_REGISTRY where
  4  comp_name='Oracle XML Database';
COMP_NAME                      STATUS                 VERSION
------------------------------ ---------------------- ----------
Oracle XML Database            VALID                  9.2.0.4.0
SQL> select  count(*) from  dba_objects where owner='XDB' and status='INVALID';
  COUNT(*)
----------
         0
SQL>   show parameter dispatchers;
NAME                                 TYPE                   VALUE
------------------------------------ ---------------------- ------------------------------
dispatchers                          string                 (PROTOCOL=TCP) (SERVICE=xffXDB)
max_dispatchers                      integer                5
mts_dispatchers                      string                 (PROTOCOL=TCP) (SERVICE=xffXDB)
mts_max_dispatchers                  integer                5
--查询证明xdb组件应该工作正常

查看xdb中ftp和http启动相关端口

SQL> select dbms_xdb.GETFTPPORT() from dual;
select dbms_xdb.GETFTPPORT() from dual
       *
ERROR at line 1:
ORA-00904: "DBMS_XDB"."GETFTPPORT": invalid identifier
SQL> select dbms_xdb.GETHTTPPORT() from dual;
select dbms_xdb.GETHTTPPORT() from dual
       *
ERROR at line 1:
ORA-00904: "DBMS_XDB"."GETHTTPPORT": invalid identifier
--9i中为提供上述查询端口的相关程序.
SQL> set long 10000
SQL> set pagesize 0
SQL> SELECT dbms_xdb.cfg_get FROM dual;
--从中找到类此这样记录,确实ftp启用2100端口,http启用8080端口
     <ftpconfig>
        <ftp-port>2100</ftp-port>
        <ftp-listener>local_listener</ftp-listener>
        <ftp-protocol>tcp</ftp-protocol>
        <session-timeout>6000</session-timeout>
     </ftpconfig>
     <httpconfig>
        <http-port>8080</http-port>
        <http-listener>local_listener</http-listener>
        <http-protocol>tcp</http-protocol>
        <session-timeout>6000</session-timeout>
        <server-name>XDB HTTP Server</server-name>
     </httpconfig>
--到这里我们可以确定是由于xdb组件中的ftp和http功能自动注册导致监听了2100和8080端口

修改xdb中监听ftp和http端口

SQL> call dbms_xdb.cfg_update(updateXML(dbms_xdb.cfg_get(),'
   2 /xdbconfig/sysconfig/protocolconfig/httpconfig/http-port/text()',8888));
Call completed.
SQL> call dbms_xdb.cfg_update(updateXML(dbms_xdb.cfg_get(),
   2 '/xdbconfig/sysconfig/protocolconfig/ftpconfig/ftp-port/text()',2222));
Call completed.
SQL> commit;
Commit complete.
SQL>  exec dbms_xdb.cfg_refresh;
PL/SQL procedure successfully completed.
SQL> exit
Disconnected from Oracle9i Enterprise Edition Release 9.2.0.4.0 - Production
With the Partitioning, OLAP and Oracle Data Mining options
JServer Release 9.2.0.4.0 - Production
[oracle@xifenfei ~]$ lsnrctl status
LSNRCTL for Linux: Version 9.2.0.4.0 - Production on 08-MAY-2012 00:57:13
Copyright (c) 1991, 2002, Oracle Corporation.  All rights reserved.
Connecting to (DESCRIPTION=(ADDRESS=(PROTOCOL=TCP)(HOST=xifenfei)(PORT=1521)))
STATUS of the LISTENER
------------------------
Alias                     LISTENER
Version                   TNSLSNR for Linux: Version 9.2.0.4.0 - Production
Start Date                08-MAY-2012 00:20:47
Uptime                    0 days 0 hr. 36 min. 26 sec
Trace Level               off
Security                  OFF
SNMP                      OFF
Listener Parameter File   /u01/oracle/9.2.0/db_1/network/admin/listener.ora
Listener Log File         /u01/oracle/9.2.0/db_1/network/log/listener.log
Listening Endpoints Summary...
  (DESCRIPTION=(ADDRESS=(PROTOCOL=tcp)(HOST=xifenfei)(PORT=1521)))
  (DESCRIPTION=(ADDRESS=(PROTOCOL=ipc)(KEY=EXTPROC)))
  (DESCRIPTION=(ADDRESS=(PROTOCOL=tcp)(HOST=xifenfei)(PORT=8888))(Presentation=HTTP)(Session=RAW))
  (DESCRIPTION=(ADDRESS=(PROTOCOL=tcp)(HOST=xifenfei)(PORT=2222))(Presentation=FTP)(Session=RAW))
Services Summary...
Service "PLSExtProc" has 1 instance(s).
  Instance "PLSExtProc", status UNKNOWN, has 1 handler(s) for this service...
Service "xffXDB" has 1 instance(s).
  Instance "xff", status READY, has 1 handler(s) for this service...
Service "xifenfei" has 2 instance(s).
  Instance "xff", status UNKNOWN, has 1 handler(s) for this service...
  Instance "xff", status READY, has 1 handler(s) for this service...
The command completed successfully

xdb中ftp和http监听

SQL> alter system reset dispatchers  scope=spfile sid='*';
System altered.
SQL> shutdown immediate;
Database closed.
Database dismounted.
ORACLE instance shut down.
SQL> startup
ORACLE instance started.
Total System Global Area  353441008 bytes
Fixed Size                   451824 bytes
Variable Size             184549376 bytes
Database Buffers          167772160 bytes
Redo Buffers                 667648 bytes
Database mounted.
Database opened.
SQL> show parameter dispatchers;
NAME                                 TYPE                   VALUE
------------------------------------ ---------------------- ---------
dispatchers                          string
max_dispatchers                      integer                5
mts_dispatchers                      string
mts_max_dispatchers                  integer                5
--SELECT dbms_xdb.cfg_get FROM dual;中信息
      <ftpconfig>
        <ftp-port>2222</ftp-port>
        <ftp-listener>local_listener</ftp-listener>
        <ftp-protocol>tcp</ftp-protocol>
        <session-timeout>6000</session-timeout>
      </ftpconfig>
      <httpconfig>
        <http-port>8888</http-port>
        <http-listener>local_listener</http-listener>
        <http-protocol>tcp</http-protocol>
        <session-timeout>6000</session-timeout>
        <server-name>XDB HTTP Server</server-name>
      </httpconfig>
[oracle@xifenfei dbs]$ lsnrctl status
LSNRCTL for Linux: Version 9.2.0.4.0 - Production on 08-MAY-2012 01:10:07
Copyright (c) 1991, 2002, Oracle Corporation.  All rights reserved.
Connecting to (DESCRIPTION=(ADDRESS=(PROTOCOL=TCP)(HOST=xifenfei)(PORT=1521)))
STATUS of the LISTENER
------------------------
Alias                     LISTENER
Version                   TNSLSNR for Linux: Version 9.2.0.4.0 - Production
Start Date                08-MAY-2012 00:20:47
Uptime                    0 days 0 hr. 49 min. 20 sec
Trace Level               off
Security                  OFF
SNMP                      OFF
Listener Parameter File   /u01/oracle/9.2.0/db_1/network/admin/listener.ora
Listener Log File         /u01/oracle/9.2.0/db_1/network/log/listener.log
Listening Endpoints Summary...
  (DESCRIPTION=(ADDRESS=(PROTOCOL=tcp)(HOST=xifenfei)(PORT=1521)))
  (DESCRIPTION=(ADDRESS=(PROTOCOL=ipc)(KEY=EXTPROC)))
Services Summary...
Service "PLSExtProc" has 1 instance(s).
  Instance "PLSExtProc", status UNKNOWN, has 1 handler(s) for this service...
Service "xifenfei" has 2 instance(s).
  Instance "xff", status UNKNOWN, has 1 handler(s) for this service...
  Instance "xff", status READY, has 1 handler(s) for this service...
The command completed successfully
--证明已经关闭了xdb 组件的ftp/http监听

xdb组件中的ftp/http监听在9i数据库中,只要你安装了xdb组件,会自动启用这功能.
在10g及其11g中默认不启用.所以为了你的数据库安全,如果不使用这些功能,建议手工关闭

我相信细心的朋友,估计都会发现我们在使用netca创建rac(10g/11g)的监听的时候，会发现 IP=FIRST,如下面展示

LISTENER_VENUS =
  (DESCRIPTION_LIST =
    (DESCRIPTION =
      (ADDRESS_LIST =
        (ADDRESS = (PROTOCOL = TCP)(HOST = racnode1-vip)(PORT = 1521)(IP = FIRST))
        (ADDRESS = (PROTOCOL = TCP)(HOST = racnode1)(PORT = 1521)(IP = FIRST))
      )
    )
  )

那么 IP=FIRST表示什么含义呢？我通过下面的试验证明

1. 主机相关配置

[oracle@localhost ~]$ hostname
localhost.localdomain
[oracle@localhost ~]$ more /etc/hosts
127.0.0.1               localhost.localdomain localhost
[oracle@localhost ~]$ /sbin/ifconfig
eth0      Link encap:Ethernet  HWaddr 00:15:17:67:9C:39
          inet addr:192.168.8.121  Bcast:192.168.15.255  Mask:255.255.248.0
          inet6 addr: fe80::215:17ff:fe67:9c39/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:378351781 errors:0 dropped:0 overruns:0 frame:0
          TX packets:357773718 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:100
          RX bytes:65412948319 (60.9 GiB)  TX bytes:92608894986 (86.2 GiB)
          Base address:0x1100 Memory:88020000-88040000
eth0:0    Link encap:Ethernet  HWaddr 00:15:17:67:9C:39
          inet addr:202.91.244.3  Bcast:202.91.247.255  Mask:255.255.248.0
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          Base address:0x1100 Memory:88020000-88040000
lo        Link encap:Local Loopback
          inet addr:127.0.0.1  Mask:255.0.0.0
          inet6 addr: ::1/128 Scope:Host
          UP LOOPBACK RUNNING  MTU:16436  Metric:1
          RX packets:40636368 errors:0 dropped:0 overruns:0 frame:0
          TX packets:40636368 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0
          RX bytes:3385490475 (3.1 GiB)  TX bytes:3385490475 (3.1 GiB)

2. 当前监听配置

SID_LIST_LISTENER =
  (SID_LIST =
      (SID_DESC =
      (SID_NAME = mcrm)
      (ORACLE_HOME = /opt/oracle/product/10.2.0/db_1)
      (GLOBAL_DBNAME =mcrm)
    )
  )
LISTENER =
  (DESCRIPTION_LIST =
    (DESCRIPTION =
      (ADDRESS = (PROTOCOL = TCP)(HOST = localhost.localdomain)(PORT = 1521)  )
)
  )

3. 监听状态

 [oracle@localhost ~]$ lsnrctl status
LSNRCTL for Linux: Version 10.2.0.4.0 - Production on 20-MAR-2012 00:17:04
Copyright (c) 1991, 2007, Oracle.  All rights reserved.
Connecting to (DESCRIPTION=(ADDRESS=(PROTOCOL=TCP)(HOST=localhost.localdomain)(PORT=1521)))
STATUS of the LISTENER
------------------------
Alias                     LISTENER
Version                   TNSLSNR for Linux: Version 10.2.0.4.0 - Production
Start Date                03-MAR-2012 23:56:18
Uptime                    16 days 0 hr. 20 min. 45 sec
Trace Level               off
Security                  ON: Local OS Authentication
SNMP                      OFF
Listener Parameter File   /opt/oracle/product/10.2.0/db_1/network/admin/listener.ora
Listener Log File         /opt/oracle/product/10.2.0/db_1/network/log/listener.log
Listening Endpoints Summary...
  (DESCRIPTION=(ADDRESS=(PROTOCOL=tcp)(HOST=localhost.localdomain)(PORT=1521)))
Services Summary...
Service "mcrm" has 2 instance(s).
  Instance "mcrm", status UNKNOWN, has 1 handler(s) for this service...
  Instance "mcrm", status READY, has 1 handler(s) for this service...
Service "mcrmXDB" has 1 instance(s).
  Instance "mcrm", status READY, has 1 handler(s) for this service...
Service "mcrm_XPT" has 1 instance(s).
  Instance "mcrm", status READY, has 1 handler(s) for this service...
The command completed successfully

这里可以看出来监听的还是(DESCRIPTION=(ADDRESS=(PROTOCOL=tcp)(HOST=localhost.localdomain)(PORT=1521)))，也就是说监听的是主机名

4. 当前监听IP和端口

[oracle@localhost ~]$ netstat -an |grep 1521|grep LISTEN
tcp        0      0 0.0.0.0:1521                0.0.0.0:*                   LISTEN

这里看出来，监听所有网卡

5. 修改监听文件

SID_LIST_LISTENER =
  (SID_LIST =
      (SID_DESC =
      (SID_NAME = mcrm)
      (ORACLE_HOME = /opt/oracle/product/10.2.0/db_1)
      (GLOBAL_DBNAME =mcrm)
    )
  )
LISTENER =
  (DESCRIPTION_LIST =
    (DESCRIPTION =
      (ADDRESS = (PROTOCOL = TCP)(HOST = localhost.localdomain)(PORT = 1521) (IP=FIRST) )
)
  )

6. 重启监听

[oracle@localhost ~]$ lsnrctl stop
LSNRCTL for Linux: Version 10.2.0.4.0 - Production on 20-MAR-2012 00:18:42
Copyright (c) 1991, 2007, Oracle.  All rights reserved.
Connecting to (DESCRIPTION=(ADDRESS=(PROTOCOL=TCP)(HOST=localhost.localdomain)(PORT=1521)(IP=FIRST)))
The command completed successfully
[oracle@localhost ~]$ lsnrctl start
LSNRCTL for Linux: Version 10.2.0.4.0 - Production on 20-MAR-2012 00:18:47
Copyright (c) 1991, 2007, Oracle.  All rights reserved.
Starting /opt/oracle/product/10.2.0/db_1/bin/tnslsnr: please wait...
TNSLSNR for Linux: Version 10.2.0.4.0 - Production
System parameter file is /opt/oracle/product/10.2.0/db_1/network/admin/listener.ora
Log messages written to /opt/oracle/product/10.2.0/db_1/network/log/listener.log
Listening on: (DESCRIPTION=(ADDRESS=(PROTOCOL=tcp)(HOST=127.0.0.1)(PORT=1521)))
Connecting to (DESCRIPTION=(ADDRESS=(PROTOCOL=TCP)(HOST=localhost.localdomain)(PORT=1521)(IP=FIRST)))
STATUS of the LISTENER
------------------------
Alias                     LISTENER
Version                   TNSLSNR for Linux: Version 10.2.0.4.0 - Production
Start Date                20-MAR-2012 00:18:48
Uptime                    0 days 0 hr. 0 min. 0 sec
Trace Level               off
Security                  ON: Local OS Authentication
SNMP                      OFF
Listener Parameter File   /opt/oracle/product/10.2.0/db_1/network/admin/listener.ora
Listener Log File         /opt/oracle/product/10.2.0/db_1/network/log/listener.log
Listening Endpoints Summary...
  (DESCRIPTION=(ADDRESS=(PROTOCOL=tcp)(HOST=127.0.0.1)(PORT=1521)))
Services Summary...
Service "PLSExtProc" has 1 instance(s).
  Instance "PLSExtProc", status UNKNOWN, has 1 handler(s) for this service...
Service "mcrm" has 1 instance(s).
  Instance "mcrm", status UNKNOWN, has 1 handler(s) for this service...
The command completed successfully

通过(DESCRIPTION=(ADDRESS=(PROTOCOL=tcp)(HOST=127.0.0.1)(PORT=1521)))，已经发现，这里只监听127.0.0.1

7. 查看监听IP和端口

[oracle@localhost ~]$ netstat -an |grep 1521|grep LISTEN
tcp        0      0 127.0.0.1:1521              0.0.0.0:*                   LISTEN

这里进一步验证监听的ip地址已经只有了127.0.0.1而没有了其他网卡的地址

总结说明
通过这里的试验证明IP = FIRST的作用使得当我们使用主机名为监听中的host配置的时候，它只会监听hostname解析出来的ip地址，而不是默认情况下所有网卡地址。

0、基本信息

[oracle@localhost ~]$ uname -a
Linux localhost.localdomain 2.6.18-194.el5PAE #1 SMP Tue Mar 16 22:00:21 EDT 2010 i686 i686 i386 GNU/Linux
[oracle@localhost ~]$ hostname
localhost.localdomain
[oracle@localhost ~]$ /sbin/ifconfig
eth0      Link encap:Ethernet  HWaddr 00:14:22:10:96:AE
          inet addr:192.168.9.66  Bcast:192.168.11.255  Mask:255.255.252.0
          inet6 addr: fe80::214:22ff:fe10:96ae/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:6597875 errors:0 dropped:0 overruns:0 frame:0
          TX packets:9785915 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:100
          RX bytes:2526369384 (2.3 GiB)  TX bytes:295978844 (282.2 MiB)
eth0:1    Link encap:Ethernet  HWaddr 00:14:22:10:96:AE
          inet addr:外网ip  Bcast:211.155.227.175  Mask:255.255.255.240
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
eth1      Link encap:Ethernet  HWaddr 00:14:22:10:96:AF
          inet addr:192.168.11.50  Bcast:192.168.11.255  Mask:255.255.252.0
          inet6 addr: fe80::214:22ff:fe10:96af/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:999903 errors:0 dropped:0 overruns:0 frame:0
          TX packets:283 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:100
          RX bytes:104688608 (99.8 MiB)  TX bytes:22777 (22.2 KiB)
lo        Link encap:Local Loopback
          inet addr:127.0.0.1  Mask:255.0.0.0
          inet6 addr: ::1/128 Scope:Host
          UP LOOPBACK RUNNING  MTU:16436  Metric:1
          RX packets:8816738 errors:0 dropped:0 overruns:0 frame:0
          TX packets:8816738 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0
          RX bytes:2726275798 (2.5 GiB)  TX bytes:2726275798 (2.5 GiB)
[oracle@localhost ~]$ more /etc/sysconfig/network
NETWORKING=yes
NETWORKING_IPV6=yes
HOSTNAME=localhost.localdomain

1、hosts文件

[oracle@localhost ~]$ more /etc/hosts
127.0.0.1                 localhost

2、监听文件

[oracle@localhost ~]$ more /opt/oracle/product/10g/network/admin/listener.ora
# listener.ora Network Configuration File: /opt/oracle/product/10g/network/admin/listener.ora
# Generated by Oracle configuration tools.
SID_LIST_LISTENER =
  (SID_LIST =
    (SID_DESC =
      (GLOBAL_DBNAME = gaxt)
      (ORACLE_HOME = /opt/oracle/product/10g)
      (SID_NAME = gaxt)
    )
  )
LISTENER =
  (DESCRIPTION_LIST =
    (DESCRIPTION =
      (ADDRESS = (PROTOCOL = TCP)(HOST = 外网IP)(PORT = 1521))
      (ADDRESS = (PROTOCOL = TCP)(HOST = 127.0.0.1)(PORT = 1521))
    )
  )

3、启动监听

[oracle@localhost ~]$ lsnrctl start
LSNRCTL for Linux: Version 10.2.0.4.0 - Production on 15-DEC-2011 23:27:32
Copyright (c) 1991, 2007, Oracle.  All rights reserved.
Starting /opt/oracle/product/10g/bin/tnslsnr: please wait...
TNSLSNR for Linux: Version 10.2.0.4.0 - Production
System parameter file is /opt/oracle/product/10g/network/admin/listener.ora
Log messages written to /opt/oracle/product/10g/network/log/listener.log
Trace information written to /tmp/listener_trc.trc
Listening on: (DESCRIPTION=(ADDRESS=(PROTOCOL=tcp)(HOST=外网IP)(PORT=1521)))
Listening on: (DESCRIPTION=(ADDRESS=(PROTOCOL=tcp)(HOST=127.0.0.1)(PORT=1521)))
Connecting to (DESCRIPTION=(ADDRESS=(PROTOCOL=TCP)(HOST=外网IP)(PORT=1521)))
--这里卡了很久很久才显示成功
STATUS of the LISTENER
------------------------
Alias                     LISTENER
Version                   TNSLSNR for Linux: Version 10.2.0.4.0 - Production
Start Date                15-DEC-2011 23:27:32
Uptime                    0 days 0 hr. 3 min. 9 sec
Trace Level               support
Security                  ON: Local OS Authentication
SNMP                      OFF
Listener Parameter File   /opt/oracle/product/10g/network/admin/listener.ora
Listener Log File         /opt/oracle/product/10g/network/log/listener.log
Listener Trace File       /tmp/listener_trc.trc
Listening Endpoints Summary...
  (DESCRIPTION=(ADDRESS=(PROTOCOL=tcp)(HOST=外网IP)(PORT=1521)))
  (DESCRIPTION=(ADDRESS=(PROTOCOL=tcp)(HOST=127.0.0.1)(PORT=1521)))
Services Summary...
Service "gaxt" has 1 instance(s).
  Instance "gaxt", status UNKNOWN, has 1 handler(s) for this service...
The command completed successfully

4、开启监听trace

--在/opt/oracle/product/10g/network/admin/listener.ora中加入下列参数
TRACE_LEVEL_LISTENER = 16
TRACE_FILE_LISTENER= LISTENER_TRC
TRACE_DIRECTORY_LISTENER=/tmp

6、重启监听查看trace文件

[15-DEC-2011 23:33:32:938] --- TRACE CONFIGURATION INFORMATION FOLLOWS ---
[15-DEC-2011 23:33:32:938] New trace stream is /tmp/listener_trc.trc
[15-DEC-2011 23:33:32:938] New trace level is 16
…………………………
[15-DEC-2011 23:33:32:981] nsnainconn: no native services in use - returning
[15-DEC-2011 23:33:32:981] nsnainconn: signalling that calling function should not continue
[15-DEC-2011 23:33:32:982] nsnainconn: normal exit
[15-DEC-2011 23:33:32:982] nsnaconn: normal exit
[15-DEC-2011 23:33:32:982] nsaccept: exit (0)
[15-DEC-2011 23:36:41:965] nsglma: WARNING - SNMP master agent is not running OR snmp.ora file does not exist.
[15-DEC-2011 23:36:41:965] nsevwait: entry
[15-DEC-2011 23:36:41:965] nsevwait: 3 registered connection(s)
[15-DEC-2011 23:36:41:965] nsevwait: 0 pre-posted event(s)
[15-DEC-2011 23:36:41:965] nsevwait: waiting for transport event (1 thru 4)...
[15-DEC-2011 23:36:41:965] nsevwait: 1 newly-posted event(s)

这里可以看出监听启动的过程中，在这个地方等待了3分钟之久
MOS:Lsnrctl Start is Extremely Slow or Appears to Hang

7、修改hosts文件

[oracle@localhost ~]$ more /etc/hosts
127.0.0.1               localhost.localdomain localhost

8、重启监听查看trace文件

[15-DEC-2011 23:43:44:555] --- TRACE CONFIGURATION INFORMATION FOLLOWS ---
[15-DEC-2011 23:43:44:555] New trace stream is /tmp/listener_trc.trc
……………………
[15-DEC-2011 23:43:44:627] nsevwait: entry
[15-DEC-2011 23:43:44:627] nsevwait: 3 registered connection(s)
[15-DEC-2011 23:43:44:627] nsevwait: 0 pre-posted event(s)
[15-DEC-2011 23:43:44:627] nsevwait: waiting for transport event (1 thru 4)...

这里可以看出监听启动一共使用时间为:几十毫秒

9、结论
在主机名为localhost.localdomain的hosts文件中缺少127.0.0.1 localhost.localdomain,哪怕监听中配置的是ip地址,也将导致监听启动时间非常长。如果主机名不是localhost.localdomain，那hosts中缺少localhost.localdomain没有影响监听启动。

一、监听异常现象

[oracle@gongantest ~]$ lsnrctl start
LSNRCTL for Linux: Version 10.2.0.4.0 - Production on 15-DEC-2011 14:15:06
Copyright (c) 1991, 2007, Oracle.  All rights reserved.
Starting /opt/oracle/product/10.2.0/db_1/bin/tnslsnr: please wait...
TNSLSNR for Linux: Version 10.2.0.4.0 - Production
System parameter file is /opt/oracle/product/10.2.0/db_1/network/admin/listener.ora
Log messages written to /opt/oracle/product/10.2.0/db_1/network/log/listener.log
Listening on: (DESCRIPTION=(ADDRESS=(PROTOCOL=tcp)(HOST=gongantest)(PORT=1521)))
Error listening on: (DESCRIPTION=(ADDRESS=(PROTOCOL=TCP)(HOST=192.168.11.60)(PORT=1521)))
TNS-12542: TNS:address already in use
 TNS-12560: TNS:protocol adapter error
  TNS-00512: Address already in use
   Linux Error: 98: Address already in use
Listener failed to start. See the error message(s) above...
[oracle@gongantest ~]$ more /opt/oracle/product/10.2.0/db_1/network/admin/listener.ora
# listener.ora Network Configuration File: /opt/oracle/product/10.2.0/db_1/network/admin/listener.ora
# Generated by Oracle configuration tools.
SID_LIST_LISTENER =
  (SID_LIST =
    (SID_DESC =
      (SID_NAME = PLSExtProc)
      (ORACLE_HOME = /opt/oracle/product/10.2.0/db_1)
      (PROGRAM = extproc)
    )
  )
LISTENER =
  (DESCRIPTION_LIST =
    (DESCRIPTION =
      (ADDRESS = (PROTOCOL = TCP)(HOST = gongantest)(PORT = 1521))
      (ADDRESS = (PROTOCOL = TCP)(HOST = 192.168.11.60)(PORT = 1521))
    )
  )

二、相关网络配置

[oracle@gongantest ~]$ ping gongantest -c 2
PING gongantest (127.0.0.1) 56(84) bytes of data.
64 bytes from gongantest (127.0.0.1): icmp_seq=1 ttl=64 time=0.040 ms
64 bytes from gongantest (127.0.0.1): icmp_seq=2 ttl=64 time=0.016 ms
--- gongantest ping statistics ---
2 packets transmitted, 2 received, 0% packet loss, time 1000ms
rtt min/avg/max/mdev = 0.016/0.028/0.040/0.012 ms
[oracle@gongantest ~]$ more /etc/hosts
# Do not remove the following line, or various programs
# that require network functionality will fail.
127.0.0.1               gongantest localhost.localdomain localhost
[oracle@gongantest ~]$ cd /etc/sysconfig/network-scripts
[oracle@gongantest network-scripts]$ more ifcfg-eth0
# Intel Corporation 82541GI Gigabit Ethernet Controller
DEVICE=eth0
BOOTPROTO=static
BROADCAST=192.168.11.255
HWADDR=00:14:22:10:96:C9
IPADDR=192.168.11.60
NETMASK=255.255.252.0
NETWORK=192.168.8.0
ONBOOT=yes
[oracle@gongantest network-scripts]$ more ifcfg-eth1
# Intel Corporation 82541GI Gigabit Ethernet Controller
DEVICE=eth1
BOOTPROTO=dhcp
HWADDR=00:14:22:10:96:CA
ONBOOT=no
HOTPLUG=no
DHCP_HOSTNAME=gongantest
[oracle@gongantest network-scripts]$ hostname
gongantest
[oracle@gongantest network-scripts]$ more /etc/sysconfig/network
NETWORKING=yes
NETWORKING_IPV6=no
HOSTNAME=gongantest
GATEWAY=192.168.8.1

三、解决问题

[oracle@gongantest ~]$ more /opt/oracle/product/10.2.0/db_1/network/admin/listener.ora
# listener.ora Network Configuration File: /opt/oracle/product/10.2.0/db_1/network/admin/listener.ora
# Generated by Oracle configuration tools.
SID_LIST_LISTENER =
  (SID_LIST =
    (SID_DESC =
      (SID_NAME = PLSExtProc)
      (ORACLE_HOME = /opt/oracle/product/10.2.0/db_1)
      (PROGRAM = extproc)
    )
  )
LISTENER =
  (DESCRIPTION_LIST =
    (DESCRIPTION =
      (ADDRESS = (PROTOCOL = TCP)(HOST = 127.0.0.1)(PORT = 1521))
      (ADDRESS = (PROTOCOL = TCP)(HOST = 192.168.11.60)(PORT = 1521))
    )
  )
[oracle@gongantest etc]$ lsnrctl start
LSNRCTL for Linux: Version 10.2.0.4.0 - Production on 15-DEC-2011 14:17:54
Copyright (c) 1991, 2007, Oracle.  All rights reserved.
Starting /opt/oracle/product/10.2.0/db_1/bin/tnslsnr: please wait...
TNSLSNR for Linux: Version 10.2.0.4.0 - Production
System parameter file is /opt/oracle/product/10.2.0/db_1/network/admin/listener.ora
Log messages written to /opt/oracle/product/10.2.0/db_1/network/log/listener.log
Listening on: (DESCRIPTION=(ADDRESS=(PROTOCOL=tcp)(HOST=127.0.0.1)(PORT=1521)))
Listening on: (DESCRIPTION=(ADDRESS=(PROTOCOL=tcp)(HOST=192.168.11.60)(PORT=1521)))
Connecting to (DESCRIPTION=(ADDRESS=(PROTOCOL=TCP)(HOST=127.0.0.1)(PORT=1521)))
STATUS of the LISTENER
------------------------
Alias                     LISTENER
Version                   TNSLSNR for Linux: Version 10.2.0.4.0 - Production
Start Date                15-DEC-2011 14:17:54
Uptime                    0 days 0 hr. 0 min. 0 sec
Trace Level               off
Security                  ON: Local OS Authentication
SNMP                      OFF
Listener Parameter File   /opt/oracle/product/10.2.0/db_1/network/admin/listener.ora
Listener Log File         /opt/oracle/product/10.2.0/db_1/network/log/listener.log
Listening Endpoints Summary...
  (DESCRIPTION=(ADDRESS=(PROTOCOL=tcp)(HOST=127.0.0.1)(PORT=1521)))
  (DESCRIPTION=(ADDRESS=(PROTOCOL=tcp)(HOST=192.168.11.60)(PORT=1521)))
Services Summary...
Service "PLSExtProc" has 1 instance(s).
  Instance "PLSExtProc", status UNKNOWN, has 1 handler(s) for this service...
The command completed successfully

四、补充说明
如果把hostname配置在hosts中的127.0.0.1项,那么如果在监听中使用了hostname,再配置一个host监听该机器的ip地址(非127.0.0.1),那么会报文章开头的错误,解决方法有两种:
1、监听中全部采用ip地址
2、在hosts中配置hostname对应ip地址(非127.0.0.1)

一、发现TNS-12525错误
检查公司服务器listener日志中周期性发现如下错误提示：

08-DEC-2011 02:25:34 * (CONNECT_DATA=(SID=ora9i)) * (ADDRESS=(PROTOCOL=tcp)(HOST=211.155.236.234)(PORT=4877)) * establish * ora9i * 0
08-DEC-2011 02:25:35 * (CONNECT_DATA=(SID=ora9i)) * (ADDRESS=(PROTOCOL=tcp)(HOST=211.155.236.234)(PORT=4879)) * establish * ora9i * 0
08-DEC-2011 02:25:43 * <unknown connect data> * (ADDRESS=(PROTOCOL=tcp)(HOST=211.155.236.234)(PORT=2486)) * establish * <unknown sid> * 12525
TNS-12525: TNS:listener has not received client's request in time allowed
 TNS-12535: TNS:operation timed out
  TNS-12606: TNS: Application timeout occurred
08-DEC-2011 02:26:02 * <unknown connect data> * (ADDRESS=(PROTOCOL=tcp)(HOST=211.155.236.234)(PORT=4876)) * establish * <unknown sid> * 12525
TNS-12525: TNS:listener has not received client's request in time allowed
 TNS-12535: TNS:operation timed out
  TNS-12606: TNS: Application timeout occurred

继续检查日志发现，只有211.155.236.234是外网ip，其他都是通过内网ip访问，都未报类此错误。初步怀疑是公司和运营商网络之间的防火墙导致

二、数据库版本

SQL> select * from v$version;
BANNER
----------------------------------------------------------------
Oracle Database 10g Enterprise Edition Release 10.2.0.4.0 - 64bi
PL/SQL Release 10.2.0.4.0 - Production
CORE    10.2.0.4.0      Production
TNS for Linux: Version 10.2.0.4.0 - Production
NLSRTL Version 10.2.0.4.0 - Production

三、MOS说明

Symptoms
At regular intervals (every three hours), you see new connections rejected with TNS-12525 "listener has not received client's request in time allowed".
The listener log shows the following error stack :
10-APR-2008 17:39:15 * <unknown connect data> * (ADDRESS=(PROTOCOL=tcp)(HOST=10.221.50.31)(PORT=4184)) * establish * <unknown sid> * 12525
  TNS-12525: TNS:listener has not received client's request in time allowed
    TNS-12535: TNS:operation timed out
      TNS-12606: TNS: Application timeout occurred
At the same time the firewall log reports :
"TCP packet out of state: First packet isn't SYN; tcp_flags: PUSH-ACK"
Wireshark (Ethereal) traces show the TCP 3-way handshake never completes for those connections.
Changes
Value of idle timer was recently changed at firewall level.
Cause
Firewall closes ports not allowing the 3-way handshake to complete at TCP level.
Solution
Increase the firewall's idle timeout interval.

New Connections Intermittently Rejected with TNS-12525

一、现状记录

[oracle@node1 ~]$ /sbin/ifconfig
eth1      Link encap:Ethernet  HWaddr 00:25:90:04:AB:6B
          inet addr:192.168.9.140  Bcast:192.168.15.255  Mask:255.255.248.0
          inet6 addr: fe80::225:90ff:fe04:ab6b/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:23530402 errors:0 dropped:0 overruns:0 frame:0
          TX packets:10959123 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0
          RX bytes:15308483748 (14.2 GiB)  TX bytes:10087987532 (9.3 GiB)
--IP地址为192.168.9.140
[oracle@node1 ~]$ more /etc/hosts
# Do not remove the following line, or various programs
# that require network functionality will fail.
127.0.0.1               ecp-db localhost.localdomain localhost
192.168.9.140   node1.srtcloud.com
--域名node1.srtcloud.com对应ip192.168.9.140
[oracle@node1 ~]$ lsnrctl status
Connecting to (DESCRIPTION=(ADDRESS=(PROTOCOL=TCP)(HOST=node1.srtcloud.com)(PORT=1521)))
STATUS of the LISTENER
------------------------
Alias                     LISTENER
Version                   TNSLSNR for Linux: Version 10.2.0.5.0 - Production
Start Date                04-NOV-2011 09:08:51
Uptime                    21 days 4 hr. 58 min. 45 sec
Trace Level               off
Security                  ON: Local OS Authentication
SNMP                      OFF
Listener Parameter File   /opt/oracle/product/10.2.0/db_1/network/admin/listener.ora
Listener Log File         /opt/oracle/product/10.2.0/db_1/network/log/listener.log
Listening Endpoints Summary...
  (DESCRIPTION=(ADDRESS=(PROTOCOL=tcp)(HOST=node1.srtcloud.com)(PORT=1521)))
Services Summary...
Service "ecp" has 2 instance(s).
  Instance "ecp", status UNKNOWN, has 1 handler(s) for this service...
  Instance "ecp", status READY, has 1 handler(s) for this service...
Service "ecpXDB" has 1 instance(s).
  Instance "ecp", status READY, has 1 handler(s) for this service...
Service "ecp_XPT" has 1 instance(s).
  Instance "ecp", status READY, has 1 handler(s) for this service...
Service "ora11g" has 2 instance(s).
  Instance "ora11g", status UNKNOWN, has 1 handler(s) for this service...
  Instance "ora11g", status READY, has 1 handler(s) for this service...
Service "ora11gXDB" has 1 instance(s).
  Instance "ora11g", status READY, has 1 handler(s) for this service...
The command completed successfully
--说明:ora11g是oracle 11g，ecp是oracle 10g
--当前使用域名node1.srtcloud.com监听
[oracle@node1 ~]$ more /opt/oracle/product/10.2.0/db_1/network/admin/tnsnames.ora
# tnsnames.ora Network Configuration File: /opt/oracle/product/10.2.0/db_1/network/admin/tnsnames.ora
# Generated by Oracle configuration tools.
ECP =
  (DESCRIPTION =
    (ADDRESS = (PROTOCOL = TCP)(HOST = node1.srtcloud.com)(PORT = 1521))
    (CONNECT_DATA =
      (SERVER = DEDICATED)
      (SERVICE_NAME = ecp)
    )
  )
ORA11G =
  (DESCRIPTION =
    (ADDRESS = (PROTOCOL = TCP)(HOST = node1.srtcloud.com)(PORT = 1521))
    (CONNECT_DATA =
      (SERVER = DEDICATED)
      (SERVICE_NAME = ora11g)
    )
  )
--tns也通过域名访问
[oracle@node1 ~]$ more /etc/resolv.conf
nameserver 211.155.235.201
nameserver 211.155.235.188
--当前有效的dns服务器
[oracle@node1 ~]$ more /etc/nsswitch.conf |grep hosts:
hosts:     files dns
--域名解析顺序

二、数据库正常工作分析
1、tns工作：客户端通过tns访问数据库，tns配置的是域名访问，所以需要解析，因为此刻解析的顺序是先利用/etc/hosts解析，所以读取hosts文件，获取到ip，然后访问对应数据库，和监听接触。
2、监听工作：监听的是域名，其实也是通过hosts解析成ip的
3、这里能够正常的工作，是因为hosts文件解析了域名

三、模拟数据库访问延迟

[oracle@node1 ~]$ more /etc/nsswitch.conf |grep hosts:
hosts:     dns files
--先使用dns服务器解析，再使用hosts文件
[oracle@node1 ~]$ more /etc/resolv.conf
nameserver 11.1.1.1
--无效的dns服务器
[oracle@node1 ~]$ sqlplus chf/xifenfei@ora11g
SQL*Plus: Release 10.2.0.5.0 - Production on Fri Nov 25 14:44:55 2011
Copyright (c) 1982, 2010, Oracle.  All Rights Reserved.
--会在这里一个很长的时间等待
[oracle@node1 ~]$ lsnrctl status
LSNRCTL for Linux: Version 10.2.0.5.0 - Production on 25-NOV-2011 14:48:26
Copyright (c) 1991, 2010, Oracle.  All rights reserved.
Connecting to (DESCRIPTION=(ADDRESS=(PROTOCOL=TCP)(HOST=node1.srtcloud.com)(PORT=1521)))
--也会一个长时间的等待
--问题原因:就是因为解析域名的时候，先去访问dns服务器，因为该ip非dns服务器ip，所以会一直等待该ip超时，
--然后访问hosts文件获取ip地址（这个就是为什么我们登录或者查看监听状态的时候，会出现如此长的时间的等待）

其实因为dns延迟的现象有很多种，我这里只是举了一个最简单，比较常见的例子，在处理因dns解析的监听延迟的问题上，可以参考下面几点:
1、如果非特殊情况，尽可能使用ip地址在监听和tns中
2、如果是使用域名，请尽可能使用hosts解析，解析顺序配置为files优先（因为dns服务器有很多不确定，不可控因素）
3、如果一定要使用dns服务器解析，请把稳定的dns服务器配置在第一项，尽可能避免出现dns服务器不可达或者不存在该域名的现象

一、官方文档说明

作用
Use the parameter SQLNET.AUTHENTICATION_SERVICES to enable one or more authentication services.
If authentication has been installed,
it is recommended that this parameter be set to either none or to one of the authentication methods.
默认值
None
一般可选值
NONE for no authentication methods. A valid username and password can be used to access the database.
ALL for all authentication methods
NTS for Windows NT native authentication(An authentication method that enables
a client single login access to a Windows NT server and a database running on the server)

为了加深对这几个参数的理解，通过实验证明，这几个参数在不同的系统中的作用

二、win系统

Microsoft Windows [版本 6.1.7601]
版权所有 (c) 2009 Microsoft Corporation。保留所有权利。
C:\Windows\system32>e:
E:\>cd E:\oracle\11_2_0\NETWORK\ADMIN
#sqlnet.ora文件不存在情况
E:\oracle\11_2_0\NETWORK\ADMIN>dir sqlnet.ora
 驱动器 E 中的卷没有标签。
 卷的序列号是 38D0-2A35
 E:\oracle\11_2_0\NETWORK\ADMIN 的目录
找不到文件
E:\oracle\11_2_0\NETWORK\ADMIN>sqlplus / as sysdba
SQL*Plus: Release 11.2.0.1.0 Production on 星期五 11月 11 22:13:57 2011
Copyright (c) 1982, 2010, Oracle.  All rights reserved.
ERROR:
ORA-01031: 权限不足
请输入用户名:
#NTS情况
E:\oracle\11_2_0\NETWORK\ADMIN>more sqlnet.ora
SQLNET.AUTHENTICATION_SERVICES=(NTS)
E:\oracle\11_2_0\NETWORK\ADMIN>sqlplus / as sysdba
SQL*Plus: Release 11.2.0.1.0 Production on 星期五 11月 11 22:16:20 2011
Copyright (c) 1982, 2010, Oracle.  All rights reserved.
连接到:
Oracle Database 11g Enterprise Edition Release 11.2.0.1.0 - Production
With the Partitioning, Oracle Label Security, OLAP, Data Mining,
Oracle Database Vault and Real Application Testing options
#NONE情况
E:\oracle\11_2_0\NETWORK\ADMIN>more sqlnet.ora
SQLNET.AUTHENTICATION_SERVICES=(NONE)
E:\oracle\11_2_0\NETWORK\ADMIN>sqlplus / as sysdba
SQL*Plus: Release 11.2.0.1.0 Production on 星期五 11月 11 22:17:18 2011
Copyright (c) 1982, 2010, Oracle.  All rights reserved.
ERROR:
ORA-01031: 权限不足
请输入用户名:
#ALL情况
E:\oracle\11_2_0\NETWORK\ADMIN>more sqlnet.ora
SQLNET.AUTHENTICATION_SERVICES=(ALL)
E:\oracle\11_2_0\NETWORK\ADMIN>sqlplus / as sysdba
SQL*Plus: Release 11.2.0.1.0 Production on 星期五 11月 11 22:18:02 2011
Copyright (c) 1982, 2010, Oracle.  All rights reserved.
ERROR:
ORA-12641: 验证服务无法初始化
请输入用户名:

三、linux系统

[oracle@report ~]$ cd /opt/oracle/product/10.2.0/db_1/network/admin/
#NTS情况
[oracle@report admin]$ more sqlnet.ora
SQLNET.AUTHENTICATION_SERVICES = (NTS)
[oracle@report admin]$ sqlplus / as sysdba
SQL*Plus: Release 10.2.0.4.0 - Production on Fri Nov 11 22:03:51 2011
Copyright (c) 1982, 2007, Oracle.  All Rights Reserved.
ERROR:
ORA-01031: insufficient privileges
Enter user-name:
#NONE情况
[oracle@report admin]$ more sqlnet.ora
SQLNET.AUTHENTICATION_SERVICES = (NONE)
[oracle@report admin]$ sqlplus / as sysdba
SQL*Plus: Release 10.2.0.4.0 - Production on Fri Nov 11 22:04:31 2011
Copyright (c) 1982, 2007, Oracle.  All Rights Reserved.
ERROR:
ORA-01031: insufficient privileges
Enter user-name:
#ALL情况
[oracle@report admin]$ more sqlnet.ora
SQLNET.AUTHENTICATION_SERVICES = (ALL)
[oracle@report admin]$ sqlplus / as sysdba
SQL*Plus: Release 10.2.0.4.0 - Production on Fri Nov 11 22:05:07 2011
Copyright (c) 1982, 2007, Oracle.  All Rights Reserved.
Connected to:
Oracle Database 10g Enterprise Edition Release 10.2.0.4.0 - 64bit Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options
#不存在sqlnet.ora文件情况
[oracle@report admin]$ ll sqlnet.ora
ls: sqlnet.ora: No such file or directory
[oracle@report admin]$ sqlplus / as sysdba
SQL*Plus: Release 10.2.0.4.0 - Production on Fri Nov 11 22:05:41 2011
Copyright (c) 1982, 2007, Oracle.  All Rights Reserved.
Connected to:
Oracle Database 10g Enterprise Edition Release 10.2.0.4.0 - 64bit Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options

四、补充说明
1、在win系统中使用all，提示ORA-12641，不是很清楚原因
2、在nts只有在win系统中有用，linux中无用
3、当不存在sqlnet.ora文件时，linux中可以正常登录，win中不能

今天在一台服务器的日志文件中，发现如下信息：

Fatal NI connect error 12170.
  VERSION INFORMATION:
	TNS for Linux: Version 11.1.0.7.0 - Production
	Unix Domain Socket IPC NT Protocol Adaptor for Linux: Version 11.1.0.7.0 - Production
	Oracle Bequeath NT Protocol Adapter for Linux: Version 11.1.0.7.0 - Production
	TCP/IP NT Protocol Adapter for Linux: Version 11.1.0.7.0 - Production
  Time: 08-NOV-2011 13:57:10
  Tracing not turned on.
  Tns error struct:
    ns main err code: 12535
TNS-12535: TNS:operation timed out
    ns secondary err code: 12560
    nt main err code: 505
TNS-00505: Operation timed out
    nt secondary err code: 110
    nt OS err code: 0
  Client address: (ADDRESS=(PROTOCOL=tcp)(HOST=10.100.107.62)(PORT=52357))

查看mos，有幸发现关于该错误的相关文章
Fatal NI connect error 12170′, ‘TNS-12535: TNS:operation timed out’ Reported in 11g Alert Log [ID 1286376.1]
做了一些摘要，算是给自己做个记录，也给不能访问mos的朋友一个参考
1、适用范围

Oracle Net Services - Version: 11.1.0.6 to 11.2.0.2 - Release: 11.1 to 11.2
Oracle Server - Enterprise Edition - Version: 11.1.0.6 to 11.2.0.2   [Release: 11.1 to 11.2]
Information in this document applies to any platform.

2、问题原因

These time out related messages are mostly informational in nature.  The messages indicate the specified client connection (identified by the 'Client address:' details) has experienced a time out.  The 'nt secondary err code' identifies the underlying network transport, such as (TCP/IP) timeout limits after a client has abnormally terminated the database connection.
The 'nt secondary err code' translates to underlying network transport timeouts for the following Operating Systems:
For the Solaris system: nt secondary err code: 145:
#define ETIMEDOUT 145 /* Connection timed out */
For the Linux operating system: nt secondary err code: 110
ETIMEDOUT 110 Connection timed out
For the HP-UX system: nt secondary err code: 238:
ETIMEDOUT 238 /* Connection timed out */
For Windows based platforms: nt secondary err code: 60 (which translates to Winsock Error: 10060)
Description:  A connection attempt failed because the connected party did not properly respond after a period of time, or established connection failed because connected host has failed to respond.
The reason the messages are written to the alert log is related to the use of the new 11g Automatic Diagnostic Repository (ADR) feature being enabled by default.

3、解决问题

To revert to Oracle Net Server tracing/logging, set following parameter in the server's sqlnet.ora :
DIAG_ADR_ENABLED = OFF
Also, to back out the ADR diag for the Listener component, set following parameter in the server's listener.ora:
DIAG_ADR_ENABLED_<listenername> = OFF
   - Where the <listenername> would be replaced with the actual name of the configured listener(s) in the listener.ora configuration file.  For example, if the listener name is 'LISTENER', the parameter would read:
DIAG_ADR_ENABLED_LISTENER = OFF
-Reload or restart the TNS Listener for the parameter change to take effect.

说明：这个问题是由于Automatic Diagnostic Repository中的 Oracle Net diagnostic在默认的情况下是开启的，当数据库和客户端的连接超过特定时间，就会把这样的信息写入到alert日志中，所以这不是一个致命的问题，如果偶尔出现，可以忽略有点类此ora-3136的错误

在一台服务器上分别安装有Oracle 10g和Oracle 11g，现在需要对这两个数据库都配置对应的监听，使其能够正常工作，本文对配置方法做了总结，供参考学习

一、动态监听
Oracle 10g listener.ora配置

Oracle 11g listener.ora配置

事项说明：
1、10g和11g两个数据库都采用动态监听，但是由于默认情况下，动态注册只会注册1521端口，所以其中一个数据库需要设置local_listener参数，用于监听其他端口
2、10g和11g两个数据库都采用动态监听，会启动两个互不干扰的监听进程

事项说明：
1、这种方法是采用一个监听实现监听所有实例，只会启动一个监听进程，只监听一个端口
2、实例中显示的为：11g一个实例，10g有两个实例的监听情况
3、这种监听方法可以在10g中配置，也可以在11g中配置，都能够正常工作

2）使用多个监听
Oracle 10g listener.ora配置

Oracle 11g listener.ora配置

事项说明： 使用了两个监听，分别监听不同的端口，对应不同的数据库