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Lesson 14 SQL*Net version 2 features
Objective Describe the Enhancements built into SQL*Net Version 2

Enhancements built into Oracle SQL*Net Version 2 (Legacy)

Enhancements to SQL*Net version 2 include multiple community access (that is, TCP/IP to LU6.2), whereby databases can connect across diverse protocols, and a multi-threaded server that allows all communications to a database to be handled through a single dispatcher, rather than with separate processes on each database.
A community is a group of computers that share a common protocol (TCP/IP, LU6.2). SQL*Net version 2 is able to cross between different communities, such that the remote request is specified by database name and all protocol conversion is automatically managed by the SQL*Net software.

Legacy Net Services

One important difference in SQL*Net version 2 is a new listener process. In SQL*Net version 1, the listener process is called ORASRV and it was started and stopped with tcpctl start and tcpctl stop.
In SQL*Net version 2, the listener is called listener, and it is started and stopped with lsnrctl start and lsnrctl stop. To further confound matters, Net8 has introduced another listener called Connection Manager (CMAN). CMAN uses a process called cmadm and cmgw. The CMAN listener is started and stopped with the "cmctl start" and "cmctl stop" commands.
Note that it is possible to have three listeners running on any Oracle server!
The following diagram illustrates the differences between connections with SQL*Net version 1 and SQL*Net version 2.
Notice that the connect strings for SQL*Net version 1 require the specification of the protocol and host name (for example, t:host:database), while SQL*Net version 2 requires only a single TNS service name. Also, SQL*Net version 2 uses the tnsnames.ora file to get the protocol and IP address before passing the request to the network.
The next lesson looks at how SQL*Net and Net8 manage database connectivity.

Legacy Diagram pertaining to Oracle Network Services: SQL*Net, versions 1 and 2

Oracle Sql Net - Exercise

Before moving on to the next lesson, click the Exercise link below for some hands-on practice in defining a TNS topology. This is the first step of the course project.
Oracle Sql Net - Exercise