Oracle Network Configuration

10g

Network Configuration |SQL*Net

About Oracle Net Services Oracle

Net

Services provides a

Secured and High-availability

network

infrastructure for Oracle environment. (Supports network communication) between a client application and a remote or local database.

Oracle Net is the transport software for communication between client and database server as well as communication between distributed database servers. Net8 (called SQL*Net prior to Oracle8). Connectivity Oracle Net Services enables a network session from a client application to an Oracle database server. Once a network session is established, Oracle Net acts as the data courier for both the client application and the database server. It is responsible for establishing and maintaining the connection between the client application and DB server, and exchanging messages between them. SQL*NET SQL*NET (OR NET8) is Oracles Client/Server Product. SQL*NET enables Clients and Servers to connect to each other. SQL*NET ( Oracle's n/w Software) allows remote data - access

between

programs and the Oracle database , or among multiple Oracle Databases. SQL*Net provides the software layer between Oracle and the networking software, communication between an Oracle client machine (for ex, SQL*Plus) and the database server or from one database server to another. Net8 is located on each machine in the network. Exploring the Oracle DBA Technology by Gunasekaran ,Thiyagu

10g

Network Configuration |SQL*Net

SQL*Net Configuration Files In most basic form , Oracle uses three files for n/w configuration. They are  listener.ora file

 On Server - Side Setup.

 tnsnames.ora file  On a Client - Side Setup.  sqlnet.ora file

 (Optional) - Either server or client side.

SQLNET.ORA

The sqlnet.ora file is the Net8 profile configuration file. This file is a text file that contains basic configuration details (encryption , default domain , tracing options etc ) and used by SQL *Net. Profiles are stored and implemented using this file. It resides on the client machines and the database server. By default, this file is located in the $ORACLE_HOME/network/admin dir. The database server can be configured with access control parameters in the sqlnet.ora file. These parameters specify whether clients are allowed or denied access based on the protocol. (Protocol Parameters  Restrict access to the database) Profile Parameters for sqlnet.ora  SEND_BUF_SIZE  RECV_BUF_SIZE  NAMES.DIRECTORY_PATH  NAMES.DEFAULT_DOMAIN  SQLNET.AUTHENTICATION_SERVICES and etc .. The sqlnet.ora file is created by running netca command. Exploring the Oracle DBA Technology by Gunasekaran ,Thiyagu

10g

Network Configuration |SQL*Net

LISTENER.ORA

Listener.ora is a SQL*Net configuration file. Listerner.ora file contains server side network configuration parameters. It is used to configure DB Listeners (to accept remote connection requests). By default , this file is located in the $ORACLE_HOME/network/admin dir. Important point to remember, should compulsorily have a listener.ora file (if users connecting from a different server). TNSNAMES.ORA

TNSNAMES.ORA is a SQL*Net Configuration file. It contains information (about the server where our database is present); For ex : ( The port no , protocol, database service_name) and etc .. This file contains net service names mapped to connect descriptors for (local naming method ) or mapped to listener protocol addresses. By default, this file is located in the $ORACLE_HOME/network/admin dir. Important point to remember, If a user wants to connect to a database, that the user would definitely need a tnsnames.ora file. POINTS TO NOTE

If million no of users are connecting to a website for ex www.google.com ; then the user don’t need to have a tnsnames.ora on their own machine , because the website is located on a web server , so the tnsnames.ora file would already be in the webserver. If NETCA runs successfully , the sqlnet.ora , tnsnames.ora and listener.ora files will be created automatically with default settings. If NETCA doesn’t succeed , it is possible to create the files manually. Exploring the Oracle DBA Technology by Gunasekaran ,Thiyagu

10g

Network Configuration |SQL*Net

SQL*Net Protocols  BEQ

Bequeath Protocol

 TCP

Transmission Control Protocol

 IPC

Inter Process Communications

 TCP/IP Transmission Control Protocol/Internet Protocol Bequeath Protocol BEQ is a SQL*Net Protocol. BEQ Connections doesn’t required a listener. BEQ only used for local connections (Similar to the IPC protocol) . BEQ enable Clients to connect to the database. I.e. (Client and Server reside on the same system). BEQ works only in Dedicated Server mode and not in Shared Server mode. Database Local connections - where an (Oracle client application - SQL*Plus) communicates with an Oracle server running on the same machine. IPC IPC Stands for Inter Process Communication. IPC is a SQL*Net protocol. A listener is required to make IPC connections. IPC only used for local connections (similar to the BEQ protocol). IPC enable Clients to connect to the database. i.e. (Client and Server reside on the same system). IPC works on Dedicated Server/Shared Server mode. Database Local connections - where an (Oracle client application - SQL*Plus) communicates with an Oracle server running on the same machine. Exploring the Oracle DBA Technology by Gunasekaran ,Thiyagu

10g

Network Configuration |SQL*Net

TCP and TCP/IP TCP and TCP/IP protocols are supported by SQL* Net. TCP Transmission control Protocol and used for (remote administration). TCP/IP is a combination of network and transport level protocols. TCP/IP is used for CLIENT/SERVER communication over a network.

TCP vs IPC  When we use IPC Connectivity ?  When we use TCP Connectivity ? We can connect to a local database without any listener only by using IPC. IPC connection does require listener! Listener only requires TCP and it is required when two different hosts are involved.  $ sqlplus scott/tiger@orcl  This is using TCP.  $ sqlplus scott/tiger

 TPC not required but IPC.

When we use ICP Connectivity ? “ IPC can only be used when the Client and Server reside on the same host ”. The (IPC) takes place between two processes within the memory space of the Operating System , so two processes must reside on the same host. Another important fact is that IPC is only be used by having the Client connect through the Oracle Listener. If the Listener is bypassed, the Client and Server processes will use the (BEQ) Bequeath protocol. Refer Oracle metalink note: IPC Explained [ID 29232.1] Exploring the Oracle DBA Technology by Gunasekaran ,Thiyagu

10g

Network Configuration |SQL*Net

Overview of LISTENER The Oracle Listener (process) is part of the Oracle network. This process is only needed on the database server side The listener is controlled via the lsnrctl utility The Listener configuration is done via listener.ora A listener is required for allowing remote (not local) clients to connect to the Oracle database via the network. LSNRCTL :- (Listener Control)

lsnrctl is an SQL*Net utility used for controlling database listeners. lsnrctl controls listener functions such as (starting/stopping listeners), and reporting status of the listeners. To invoke "lsnrctl" utility from the command line. $ lsnrctl LSNRCTL for Linux : Version 10.2.0.1.0 - Production on 02-MAR-2013 09:42:19 Copyright (c) 1991, 2005, Oracle. All rights reserved. Welcome to LSNRCTL, type "help" for information. LSNRCTL> help

The following operations are available An asterisk (*) denotes a modifier or extended command : start

stop

status

services

version

reload

save_config

trace

spawn

change_password

quit

exit

set*

show*

Exploring the Oracle DBA Technology by Gunasekaran ,Thiyagu

10g

Network Configuration |SQL*Net

POINTS TO NOTE :

When a client requests a connection to the DB, (If it is remote to the server) Clients first contact a listener process (typically resides on DB Server), The listener primary purpose is receives incoming client connection requests and sends these requests to the DB Server. After the connection is established, the client and database server communicate directly. We can configure multiple listeners, each with unique name , in listener.ora file. Listener configuration stored in listener.ora file. $ cat listener.ora (Files edits are in RED ) SID_LIST_LISTENER= (SID_LIST= (SID_DESC= (GLOBAL_DBNAME= orcl.orgdb.com) (ORACLE_HOME=/u01/app/oracle/product/10.2.0/db_1) (SID_NAME=orcl ) ) LISTENER = (DESCRIPTION_LIST = (DESCRIPTION = (ADDRESS = (PROTOCOL = TCP)(HOST =MYSERVER)(PORT = 1521)) ) )

DB_NAME and DB_DOMAIN

parameters combine to create the global

database name and the value assigned to service_names parameter. Exploring the Oracle DBA Technology by Gunasekaran ,Thiyagu

10g

Network Configuration |SQL*Net

LSNRCTL Commands  Start a listener  Stop a listener  Reload a listener  Checking listner status  Checking Registered Services To Start a listener lsnrctl> start listener_name To Stop a listener lsnrctl> stop listener_name Reload a listener lsnrctl> reload listener_name To reload a database listener (stop and restart without disrupting the service). Check listener status lsnrctl> status listener_name Status about the listener, including start date, uptime and trace level.

Check registered services lsnrctl> services listener_name To see what database services is registered with a listener: lsnrctl> version Displays the version information of the listener.

Exploring the Oracle DBA Technology by Gunasekaran ,Thiyagu

10g

Network Configuration |SQL*Net

NETCA NETCA stands for NETwork Configuration Assistant.

NETCA utility is used to configure SQL*Net. Screen shots are taken from an OEL system with Oracle 10gR2.

Select add

Exploring the Oracle DBA Technology by Gunasekaran ,Thiyagu

10g

Network Configuration |SQL*Net

The default name is LISTENER. (if we wish to change , it is possible)

Select which protocols the Listener will use. TCP is selected by default.

Click Next .. Exploring the Oracle DBA Technology by Gunasekaran ,Thiyagu

10g

Network Configuration |SQL*Net

The default port number used by an Oracle Listener is 1521

No Option is selected and click the Next button to continue.

Click Next .. Exploring the Oracle DBA Technology by Gunasekaran ,Thiyagu

10g

Network Configuration |SQL*Net

The Listener configuration is complete. Click the Next button to complete the Listener configuration wizard and to return the welcome page.

The Listener configuration is completed successfully and that the Listener was started. Here the listener name is LISTENER_ORCL .

We can validate that the Listener is running by issuing lsnrctl status. In oracle Terminology , there are two ways database instance registering with the listener. They are STATIC/DYNAMIC instance registration. Exploring the Oracle DBA Technology by Gunasekaran ,Thiyagu

10g

Network Configuration |SQL*Net

Starting up and shutting down the oracle listener is a routine task for a database administrator. Let us check how to start, stop, check status of an oracle listener using Oracle listener control utility LSNRCTL Before starting, stopping or restarting a listener, manually need to execute lsnrctl status command to check the oracle listener status. If Oracle Listener is not running ; [ Error Message ] $ lsnrctl status LSNRCTL for Linux: Version 10.2.0.1.0 - Production on 08-MAR-2013 21:02:08 Copyright (c) 1991, 2005, Oracle. All rights reserved. Connecting to (ADDRESS=(PROTOCOL=tcp)(HOST=)(PORT=1521)) TNS-12541: TNS:no listener TNS-12560: TNS:protocol adapter error TNS-00511: No listener Linux Error: 111: Connection refused Oracle listener is not running , so manually start the listener $ lsnrctl start listener_orcl LSNRCTL for Linux: Version 10.2.0.1.0 - Production on 08-MAR-2013 21:24:34 Copyright (c) 1991, 2005, Oracle. All rights reserved. Starting /u01/app/oracle/product/10.2.0/db_1/bin/tnslsnr: please wait... TNSLSNR for Linux: Version 10.2.0.1.0 - Production System parameter file is /u01/app/oracle/product/10.2.0/db_1/network/admin/listener.ora Log messages written to

Exploring the Oracle DBA Technology by Gunasekaran ,Thiyagu

10g

Network Configuration |SQL*Net

/u01/app/oracle/product/10.2.0/db_1/network/log/listener_orcl.log Listening on: (DESCRIPTION=(ADDRESS=(PROTOCOL=tcp)(HOST=linuxserver)(PORT=1521))) Connecting to (DESCRIPTION=(ADDRESS=(PROTOCOL=TCP)(HOST=linuxserver)(PORT=1521))) STATUS of the LISTENER Alias

listener_orcl

Version

TNSLSNR for Linux: Version 10.2.0.1.0 - Production

Start Date

08-MAR-2013 21:24:34

Uptime

0 days 0 hr. 0 min. 0 sec

Trace Level

off

Security

ON: Local OS Authentication

SNMP

OFF

Listener Parameter File /u01/app/oracle/product/10.2.0/db_1/network/admin/listener.ora Listener Log File /u01/app/oracle/product/10.2.0/db_1/network/log/listener_orcl.log Listening Endpoints Summary... (DESCRIPTION=(ADDRESS=(PROTOCOL=tcp)(HOST=linuxserver)(PORT=1521))) Services Summary... Service "MYDB.PROD.ORCLPROD.COM" has 1 instance(s). Instance "orclprod", status UNKNOWN, has 1 handler(s) for this service... Service "MYDB.TEST.ORCLTEST.COM" has 1 instance(s). Instance "orcltest", status UNKNOWN, has 1 handler(s) for this service... The command completed successfully Listener name is not case sensitive. i.e listener_ORCL= listener_orcl ; Exploring the Oracle DBA Technology by Gunasekaran ,Thiyagu

10g

Network Configuration |SQL*Net

Listener is running and I am going to stop the listener $ lsnrctl stop LISTENER_ORCL LSNRCTL for Linux: Version 10.2.0.1.0 - Production on 09-MAR-2013 11:05:23 Copyright (c) 1991, 2005, Oracle. All rights reserved. Connecting to (DESCRIPTION=(ADDRESS=(PROTOCOL=TCP)(HOST=linuxserver)(PORT=1521))) The command completed successfully Reloading the listener $ lsnrctl reload LISTener_ORcl LSNRCTL for Linux: Version 10.2.0.1.0 - Production on 09-MAR-2013 12:02:58 Copyright (c) 1991, 2005, Oracle. All rights reserved. Connecting to (DESCRIPTION=(ADDRESS=(PROTOCOL=TCP)(HOST=linuxserver)(PORT=1521))) The command completed successfully Checking Registered Services with Listener $ lsnrctl services LSNRCTL for Linux: Version 10.2.0.1.0 - Production on 09-MAR-2013 12:28:55 Copyright (c) 1991, 2005, Oracle. All rights reserved. Connecting to (ADDRESS=(PROTOCOL=tcp)(HOST=)(PORT=1521)) Services Summary... Service "MYDB.PROD.ORCLPROD.COM" has 1 instance(s). Instance "orclprod", status UNKNOWN, has 1 handler(s) for this service... Handler(s): "DEDICATED" established:3 refused:0

Exploring the Oracle DBA Technology by Gunasekaran ,Thiyagu

Network Configuration |SQL*Net

10g

LOCAL SERVER Service "MYDB.TEST.ORCLTEST.COM" has 1 instance(s). Instance "orcltest", status UNKNOWN, has 1 handler(s) for this service... Handler(s): "DEDICATED" established:8 refused:0 LOCAL SERVER The command completed successfully Listener help Show $ lsnrctl help show LSNRCTL for Linux: Version 10.2.0.1.0 - Production on 09-MAR-2013 12:44:04 Copyright (c) 1991, 2005, Oracle. All rights reserved. The following operations are available after show An asterisk (*) denotes a modifier or extended command: rawmode

displaymode

rules

trc_file

trc_directory

trc_level

log_file

log_directory

log_status

current_listener

inbound_connect_timeout snmp_visible

startup_waittime

save_config_on_stop

About HOST=localhost/127.0.0.1  linux> # cat /etc/hosts 127.0.0.1 xxxx xxxxx localhost If listner configuration is specified "HOST=localhost" or "HOST=127.0.01". This is a NONROUTABLE IP address . Exploring the Oracle DBA Technology by Gunasekaran ,Thiyagu

10g

Network Configuration |SQL*Net

In # cat etc/ hosts file LOCALHOST and IP ADDRESS 127.0.0.1 always mean "This machine on which I am sitting". So, all computers are known as "localhost" or "127.0.0.1". FYI - No remote client can ever connect to DB Server using 127.0.0.1 NOTE : If we specify this address, the listener will only be capable of receiving requests from the machine on which it is running. Some Points to Remember The listener is a server side process only. It creates the connection. It doesn't sustain the connection. It's entire purpose is to receive requests for connections to databases and set up those connections. Once the connection is established, the listener is out of the picture. Configure Naming Methods : ( Client ) Lets us configure connectivity for client connections to the database server. Oracle Net supports four(4) naming methods.  Local Naming  External Naming  Directory Naming  Easy Connect Naming ( EZCONNECT) EZCONNECT : EZCONNECT is Oracle's easy connect naming method for TCP/IP environments. This method enables clients to connect to a database server without any configuration. Exploring the Oracle DBA Technology by Gunasekaran ,Thiyagu

10g

Network Configuration |SQL*Net

LOCAL NAMING : A net service_name stored in tnsnames.ora on a client. The local naming method stores connect descriptors, identified by their net service name, in a configuration file (tnsnames.ora). Connection Requests When users initiate a connection request , should provide connect string; A connect string includes a username and password, and a connect identifier; One of the most common connect identifiers is a net service name; Here , connect string that uses the net service name; An example of a Complete Connection String could be scott/tiger@orcl.  SQLPLUS username/password@net_service_name  CONNECT username/password@net_service_name “@” symbol is used to mark the beginning of the connect identifier so the connect identifier is “orcl”. When net service name is used , connection processing first mapping to the connect descriptor. The mapped information that are accessed with naming methods. Understading the TNSNAMES.ORA File The

tnsnames.ora

is

a

network

configuration

file

that

contains

net_service_name mapped to connect descriptor for the local naming method. The tnsnames.ora file is used by clients to identify server destination. By default , tnsnames.ora is located in the $ORACLE_HOME/network/admin directory on UNIX/LINUX operating systems.

Exploring the Oracle DBA Technology by Gunasekaran ,Thiyagu

10g

Network Configuration |SQL*Net

Connect Descriptor: Connect Descriptor (TNS Connect String). When a Client needs to connect an

Oracle Server, should supply three

pieces of information USERID/PASSWORD@NET_SERVICE_NAME. The net service name provides all necessary information, in the form of a connect descriptor. The CONNECT DESCRIPTOR usually having two parts .  ADDRESS DATA Section  CONNECT_DATA Section ( DESCRIPTION= ( ADDRESS=(address specific things) ) ( CONNECT_DATA= (connect data specific things ) ))

The Address data part contains

PROTOCOL/HOST/PORT.

The Connect data part contains

SERVER/SERVICE_NAME.

The service_name can be same as ORACLE_SID or Global_dbname (defult). A Connect Descriptor mapping to simple name : ORCLMYTEST ORCLDB , orcltest = (DESCRIPTION= (ADDRESS_LIST =

(ADDRESS= (PROTOCOL=TCP) (HOST=MYSERVER) (PORT=1521)) ) (CONNECT_DATA= (SERVICE_NAME= orcl.orcldb.com) (SERVER=DEDICATED ) )

)

In this example, the destination service is a DB service named orcl.orgdb.com. Exploring the Oracle DBA Technology by Gunasekaran ,Thiyagu

10g

Network Configuration |SQL*Net

A Complete Connect Descriptor CONNECT

scott/tiger@(DESCRIPTION=(ADDRESS= (PROTOCOL=tcp)

(HOST=MYSERVER) (PORT=1521)) (CONNECT_DATA= (SERVICE_NAME= orcl.orgdb.com)))

Example for tnsnames.ora file File edits are in RED ORCLDB , orcltest =

TNS alias name

DESCRIPTION = (ADDRESS_LIST= (ADDRESS = (PROTOCOL = TCP) (HOST=MYSERVER) ( PORT = 1521))

must, match port in listener.ora

) (CONNECT_DATA = (SERVER=DEDICATED) (SERVICE_NAME =orcl.orcldb.com) ) ) POINTS TO NOTE  The net_service_names are

‘ORCLDB , ‘orcltest ’.

 The service_name is obviously "orcl.orcldb.com" . 'net_service_name' is just another term , same thing as 'tns_alias_name'. Oracle provides for the ability to have multiple tnsnames aliases for connection to the same database instance in a standard TNSNAMES.ORA. Exploring the Oracle DBA Technology by Gunasekaran ,Thiyagu

10g

Network Configuration |SQL*Net

POINTS TO REMEMBER Oracle Net Services , enables a network session from a client application to an Oracle Database server. Oracle Net is responsible for establishing and maintaining the connection between the client application and database, as well as exchanging messages between them.

Oracle Client Software is required on workstations. A client uses a service name to identify the database. Service name is an identifier of a database service. Clients use a connect identifier in the connect string to connect to a service. The connect identifier (sales) that maps to a connect descriptor. A connect descriptor mapped to simple name called sales. A connect descriptor is comprised of PROTOCOL/HOST/PORT and the connect information for the destination service. sales= (DESCRIPTION= (ADDRESS= (PROTOCOL=tcp)(HOST=sales-server)(PORT=1521)) (CONNECT_DATA= (SERVICE_NAME=sales.us.example.com)))

If we don’t specify service_name for the database , the service name is default to the database's global_name; DB_NAME parameter and the DB_DOMAIN name parameter combine to create the global database name and value assigned to the SERVICE_NAMES in the initialization parameter file. Exploring the Oracle DBA Technology by Gunasekaran ,Thiyagu

10g

Network Configuration |SQL*Net

 SQLPLUS system/oracle@MYORCL  system/oracle – is the username/password MYORCL – an alias. @ – sign indicates that you want to connect to a remote database. sqlplus – is the binary executable tool you can use to connect to Oracle. The tnsnames.ora file that will point to the database server to connect. In order to allow remote connections to an Oracle database the database must be registered with an Oracle Listener. When an instance , it registers itself with a listener using one or more service names. PMON process registers instance information with a listener. A listener is required for allowing remote (not local) clients to connect to the Oracle database via the network. A listener.ora file contains  Name of the listener  Database services  Protocol addresses that the listener is accepting connection requests  Address to make remote connection (hostname, listenerport) The listener knows which services can handle connection requests because an Oracle database dynamically registers this information with the listener. This process of registration is called service registration. If the client is on the same machine as the db instance, it is possible to connect without referencing tnsnames and

without going through the

listener. Now, we can issue a connect , sqlplus scott/tiger

Exploring the Oracle DBA Technology by Gunasekaran ,Thiyagu

10g

Network Configuration |SQL*Net

Tnsnames.ora and Listener.ora

Exploring the Oracle DBA Technology by Gunasekaran ,Thiyagu

10g

Network Configuration |SQL*Net

PING and TNSPING

Using ping command , we can verify client connectivity.

If ping doesn’t work, then client is having network issues, and there is no problem with the server. When a web browser fails to connect to a web site on the Internet or LAN (local area network) the cause is often the web server, which may be down or overloaded or network failiure. Exploring the Oracle DBA Technology by Gunasekaran ,Thiyagu

10g

Network Configuration |SQL*Net

TNSPING

tnsping is a utility in the $ORACLE HOME/bin directory. tnsping does only tries to reach (ping) the listener. tnsping is used to test (SQL*Net) connect string can connect to a listener. tnsping tests the connection is okay ( tnsping will only report if the listener process is up ) and the port is open. It doesn’t guarantee that the database is

up and running. It doesn't try to connect to the database.

The connection

can be established from a client to a server (or server to server).

To Invoke the TNSPING Utility using net service_name $ tnsping net_service_name must exist in tnsnames.ora file. If the net service name specified , tnsping utility attempts to contact the corresponding listener. It doesn’t actually determine whether or not the database itself is running.  $ tnsping  $ tnsping ORCLTEST

 $ tnsping  $ tnsping ORCLTEST 5 The “count” parameter is optional and will show the number of times the command try to connect to the specified net_service_name. The tnsping reports the number of milliseconds it took to reach the remote service. Exploring the Oracle DBA Technology by Gunasekaran ,Thiyagu

10g

Network Configuration |SQL*Net

TNSPING Utility Using net_service_name

$ tnsping ORCLTESTDB TNS Ping Utility for Linux: Version 10.2.0.1.0 - Production on 13-MAR-2013 05:13:23 Copyright (c) 1997, 2005, Oracle. All rights reserved. Used parameter files: Used TNSNAMES adapter to resolve the alias Attempting to contact (DESCRIPTION = (ADDRESS = (PROTOCOL = TCP)(HOST = linuxserver)(PORT = 1521)) (CONNECT_DATA = (SERVER = DEDICATED) (SERVICE_NAME = orcltest))) OK (10 msec)) TNSPING Utility Using net_service_name with Count

$ tnsping orclproddb 4 TNS Ping Utility for Linux: Version 10.2.0.1.0 - Production on 13-MAR-2013 Copyright (c) 1997, 2005, Oracle. All rights reserved. Used parameter files: Used TNSNAMES adapter to resolve the alias Attempting to contact (DESCRIPTION = (ADDRESS = (PROTOCOL = TCP)(HOST = linuxserver)(PORT = 1521)) (CONNECT_DATA = (SERVER = DEDICATED) (SERVICE_NAME =MYDB.PROD.ORCLPROD.COM))) OK (10 msec) OK (10 msec) OK (10 msec) OK (20 msec) Exploring the Oracle DBA Technology by Gunasekaran ,Thiyagu

10g

Network Configuration |SQL*Net

Some Additional Information about TNSNAMES.ORA The tnsnames.ora is a network configuration file for the local naming method on client side. This file is used by clients used to identify server destinations. In this file net service names

mapped to

connect descriptor.

connect descriptor contains two sets of data ; They are  ADDRESS_LIST and  CONNECT_DATA DESCRIPTION -- ADDRESS_LIST ----ADDRESS ------PROTOCOL=TCP -----HOST=LINUXSERVER ------PORT=1521 ----CONNECT_DATA ---SERVER=DEDICATED ------SERVICE_NAME=orcltest

ADDRESS describes how to connect to the server; CONNECT_DATA describes how to connect to a specific database instance; SERVER=DEDICATED tells the client to make a direct connection to the server. General Syntax of tnsnames.ora Basic syntax for a tnsnames.ora file net_service_name= (DESCRIPTION= (ADDRESS=(protocol_address_information))

connect_descriptor

(CONNECT_DATA= (SERVICE_NAME=service_name)))

In this ex : DESCRIPTION contains the connect descriptor, ADDRESS contains the protocol address, and CONNECT_DATA contains the database service identification information. Exploring the Oracle DBA Technology by Gunasekaran ,Thiyagu

10g

Network Configuration |SQL*Net

Oracle Net Naming Methods In Oracle 10g , Oracle Net provides four naming methods. They are  Local Naming  Directory Naming  Easy Connect Naming  External Naming LOCAL NAMING

The local naming method stores connect descriptors, identified by their net service name, in a configuration file (tnsnames.ora) on the client side. EASY CONNECT NAMING (Central with an LDAP) EZCONNECT is Oracle's Easy Connect naming method.

The easy connect naming method requires no configuration. The easy connect naming method eliminates the need for service name lookup in the tnsnames.ora files for TCP/IP environments. To Invoke EZCONNECT Method  SQL> CONNECT username/password@host[:port][/service_name]  SQL> CONNECT hr/hr@my-server:1521/mydb HOST/PORT/SERVICE_NAME are required to connect EZCONNECT method. DIRECTORY NAMING

The directory naming method stores connect identifiers in a centralized, LDAPCompliant dir server. Ths is apt for large org with several databases. Exploring the Oracle DBA Technology by Gunasekaran ,Thiyagu

10g

Network Configuration |SQL*Net

DATABASE Connectivity using Easy Connect Method

Exploring the Oracle DBA Technology by Gunasekaran ,Thiyagu

10g

Network Configuration |SQL*Net

DATABASE Connectivity using net_service_name : (TCP - Protocol)

Exploring the Oracle DBA Technology by Gunasekaran ,Thiyagu

10g

Network Configuration |SQL*Net

DATABASE Connectivity using net_service_name : (IPC - Protocol)

Exploring the Oracle DBA Technology by Gunasekaran ,Thiyagu