Lesson 9

In essence, while the fundamental purposes of CMAN

1. access control and
2. session multiplexing

remain consistent, Oracle 23c introduces significant enhancements, particularly with the evolution of CMAN in Traffic Director Mode (TDM)^[1]. Here is a breakdown of the changes and continuities:
Core Functionality (Remains Consistent):

• Access Control: CMAN continues to act as a network firewall, allowing administrators to define rule-based access to database servers. This filtering of client connection requests based on source, destination, and service is still a primary function.
• Session Multiplexing: The ability to funnel multiple client sessions through a single network connection to a shared server destination persists. This is crucial for optimizing network resource utilization, especially in environments with a large number of clients.

Key Changes and Enhancements in Oracle 23c:

• Traffic Director Mode (TDM) Enhancements: This is the most significant evolution. Introduced in later 11g releases and significantly enhanced in subsequent versions, including 23c, CMAN in TDM offers:
  • Transparent Performance Enhancements and Connection Multiplexing: TDM aims for improved performance and more efficient multiplexing, often transparent to the application.
  • Zero Application Downtime: A major focus of TDM is to minimize or eliminate application downtime during planned database maintenance (like patching or PDB relocation) and even some unplanned outages (for read-mostly workloads). It achieves this through connection draining and redirection.
  • High Availability of CMAN: TDM architectures in 23c are designed for high availability, eliminating single points of failure for the connection management layer.
  • Security and Isolation: TDM maintains and enhances security and isolation between connections.
  • Implicit Connection Pooling: Oracle 23c provides "implicit connection pooling" for CMAN in TDM, aiming for higher concurrency and optimized database resource usage with minimal application code changes (primarily configuration).
  • Support for Direct Path Applications: Enhancements in 23c extend TDM support to applications using direct path operations.
  • Usage Statistics: Oracle 23c provides more detailed usage statistics for CMAN in TDM, aiding in monitoring and management.
• Integration with Multitenant Architecture: In Oracle 23c, CMAN is more tightly integrated with the multitenant architecture, offering better support for managing connections to Container Databases (CDBs) and Pluggable Databases (PDBs).
• Enhanced Security Features: While security has always been a part of CMAN, newer versions like 23c likely incorporate advancements in network security protocols and integration with Oracle's broader security framework.
• Simplified Management: Oracle has been focusing on simplifying database administration. While specific details on CMAN management simplification in 23c would be in the administration guides, it's a general trend across Oracle products.

Discontinuations/Deprecations (Less Likely for Core CMAN):
It is important to note that Oracle often deprecates older features in new releases. However, given that access control and connection multiplexing remain fundamental networking requirements, it's less likely that the core functionality of CMAN would be deprecated. Instead, older modes of operation or specific parameters might be superseded by newer, more efficient approaches within TDM.
In Summary: The role of Oracle Connection Manager has evolved from a primarily access control and session multiplexing tool in Oracle 11g to a more sophisticated connection management hub in Oracle 23c, especially with the advancements in Traffic Director Mode. The focus has shifted towards higher availability, seamless application continuity during maintenance, and improved performance and resource utilization in modern Oracle environments, including those leveraging the multitenant architecture.
To get the most precise details on specific parameter changes, new features, and potential deprecations, consulting the Oracle Net Services Administrator's Guide for both Oracle 11g and Oracle 23c would be highly beneficial.

Oracle Connection Manager is a software component that resides on its own computer, separate from a client or an Oracle Database server. Oracle Connection Manager proxies and screens requests for the database server. In addition, it multiplexes database sessions. In its session multiplexing role, Oracle Connection Manager funnels multiple sessions through a single transport protocol connection to a particular destination. Using this technology, Oracle Connection Manager reduces the demand on resources needed to maintain multiple sessions between two processes by enabling the Oracle Database server to use fewer connection end points for incoming requests. As an access control filter, Oracle Connection Manager controls access to Oracle databases.
This module discussed networking capabilities available in Network Services, especially in the area of security and connection tuning.
In this module, you learned how to:

1. Configure and run the Connection Manager
2. Identify scenarios where connection pooling is beneficial
3. Configure a network for load balancing
4. Identify situations where automatic instance registration can be an advantage
5. Define the RADIUS adapter and its purpose
6. Describe what needs to be configured to use RADIUS adapter

Oracle 23c still needs to be configured for multiplexing, especially for critical files like:

• Control files
• Redo log files
• Archived log files

Although Oracle 23c introduces many "autonomous and cloud-native features", multiplexing remains a best practice for data protection, high availability, and fault tolerance, particularly in on-premise, hybrid, or non-autonomous cloud deployments.
🔁 What Is Multiplexing in Oracle?
Multiplexing means maintaining "multiple copies" of important files so that if one copy becomes unavailable or corrupted, another can take over seamlessly. It primarily applies to:

1. Control Files: Manage database structure and recovery metadata.
2. Online Redo Log Files: Capture transactional changes.
3. Archived Redo Logs: Used for point-in-time recovery (if ARCHIVELOG is enabled).

🛠️ How to Configure Multiplexing in Oracle 23c

1. Control File Multiplexing
   • Update CONTROL_FILES parameter in spfile or init.ora:
     

     ALTER SYSTEM SET CONTROL_FILES =
     '/u01/oradata/dbname/control01.ctl',
     '/u02/oradata/dbname/control02.ctl' SCOPE=SPFILE;
     

   • Restart the database for changes to take effect.
2. Redo Log Multiplexing
   • Create multiple members per redo log group:
     

     ALTER DATABASE ADD LOGFILE MEMBER
     '/u02/oradata/dbname/redo01b.log' TO GROUP 1;
     

   • Repeat for all log groups.
3. Archived Log Multiplexing (Optional)
   • You can specify multiple archive destinations:
     

     ALTER SYSTEM SET LOG_ARCHIVE_DEST_1='LOCATION=/u01/arch/';
     ALTER SYSTEM SET LOG_ARCHIVE_DEST_2='LOCATION=/u02/arch/';
     

✅ Multiplexing in Oracle 23c Autonomous Environment?

• No manual configuration is required, since Oracle Autonomous Database manages this internally.
• But for non-autonomous or user-managed 23c environments, you must configure multiplexing as in prior versions.

🔐 Summary

File Type	Multiplexing Required?	Configurable by DBA?
Control File	✅ Yes	✅ Yes
Redo Log	✅ Yes	✅ Yes
Archive Log	✅ Recommended	✅ Yes
Datafiles	❌ (Handled by ASM or FRA mirroring)	🟡 Depends

The following terms were defined in this module:

1. Connection load balancing: A feature of Net8 that reviews the load on each of a group of database services or database dispatchers, and then selects the least busy available service or dispatcher and assigns a new connection to it.
2. Connection Manager: A service that can be run along with Net8 to control multiple connections going to a Multi-Threaded Server.
3. Multiplexing: Combining several individual transmissions and sending them across a single connection to and from a database.
4. Connection Pooling: A feature of Multi-Threaded Server in which idle user connections are re-used temporarily, allowing more concurrent users to reach the database.
5. RADIUS: Acronym for Remote Authentication Dial-In User Service, a client-server security protocol that is used primarily with the Internet.

In the next module, you will learn about features of Oracle23c for distributed databases.

Click the Quiz link below to test your understanding of RADIUS and automated instance registration.
Automated Instance Registration - Quiz

[1]CMAN in Traffic Director Mode (TDM): In Oracle 23c, CMAN in Traffic Director Mode (TDM) acts as an intelligent connection proxy situated between database clients and servers. This mode enhances connection management by offering features like transparent connection pooling and multiplexing, which optimizes resource utilization. Furthermore, CMAN TDM provides high availability and zero downtime for applications during planned maintenance or outages by intelligently redirecting connections.