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CHAPTER 19

Oracle Networking Fundamentals

In this chapter

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Understanding Oracle Networking Product Features

Oracle Network Products—SQL*Net in the Oracle7 environment and Net8 in Oracle8—are Oracle's networking solution for transparent client-to-server and server-to-server application connectivity. These products contain a rich core of network services, including data transport, network naming, security, and transaction monitoring. These Oracle Network Products form an abstraction layer, insulating users and user applications from the physical network, allowing heterogeneous, distributed computing across computers regardless of vendor, operating system, hardware architecture, or network topology. Applications will work as written on an AS-400 with LU6.2 network protocol, on a token-ring network, or on an HP-9000 with TCP/IP network protocol on an ethernet network. Oracle SQL*Net is available on virtually every platform supported by Oracle, from PCs to mainframes, and supports almost every network transport protocol, including TCP/IP, Novell SPX/IPX, IBM LU6.2, NetBIOS, DECNet, and AppleTalk.

The Oracle Network architecture offers excellent performance for all it does. In Oracle7, SQL*Net supports network load balancing and fault tolerance. When multiple paths to the database server exist, SQL*Net determines which route is the most efficient and establishes the connection accordingly. Additionally, during connection setup, SQL*Net will detect any component failures on the primary path and will automatically switch to an alternate route if possible, using secondary network interfaces or network software protocol stacks. SQL*Net will also detect a broken connection and release all server resources, cleaning up failed connections.

Oracle8 and Net8 surpass the SQL*Net family in performance and scalability through two new features: connection pooling and session multiplexing. These technologies reduce the amount of server-system resources needed to support network connections, allowing a single database server to support increasing numbers of users. In Oracle8 Enterprise Edition, a new middle-ware application called Oracle Connection Manager takes advantage of the multiplexing feature to act as a high-speed proxy to a database server. As a proxy, Oracle Connection Manager acts as a firewall, controlling network-level access to the database server for enhanced network security.

Other standard features available in all Oracle Network Products:

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Understanding the Administration and Management Components

Oracle Network Products include a comprehensive set of administration and management components. SQL*Net's graphical management facility, Oracle Network Manager for Oracle7 and Net8 Assistant for Oracle8, are powerful tools for creating and managing an Oracle network. Oracle Net8 Assistant supersedes Oracle Network Manager by providing a Java-based tool that is driven by a wizards interface. Using these tools, the administrator can configure all components of the Oracle SQL*Net family, including database servers, gateways, clients, and Oracle MultiProtocol Interchanges, either centrally or in a distributed fashion. Oracle Net8 Assistant runs on most desktop and UNIX operating systems, but Oracle Network Manager is only for desktop systems.

Oracle Names, the Oracle global naming service, is also fully administered and maintained through the above tools. Oracle Names allows administrators to define network entities (such as service addresses, database aliases, and so on).

SQL*Net and Net8 include support for the Simple Network Management Protocol (SNMP). The Oracle7 and Oracle8 servers (as well as Network Listener, MultiProtocol Interchange, and Oracle Names) can be monitored by SNMP-based network management consoles, such as Oracle Enterprise Manager and HP OpenView. This allows existing network operation centers in a company to include Oracle systems in their proactive monitoring.

Other administrative components and features include:

Network Naming Conventions

One of the challenges in a large organization is producing unique names for all network resources. The common flat model naming system, where objects are given a single unique name, often falls short in the enterprise. For this reason, Oracle supports naming network resources using a domain hierarchy. In a domain model, network resources are named according to the group they fall in or the purpose they serve. For example, the marketing department

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in the Oracle Corporation may belong to the marketing.oracle.com domain. TNS resources belonging to the marketing department would be named using this domain—for example, prod01.marketing.oracle.com for a production database or listener01.marketing.oracle.com for a listener.

In version 7.3 of the Oracle database, TNS resources are placed in the world domain if no domain is created for them. This ensures that network applications expecting a domain name will always have one, even if the organization has implemented a flat naming hierarchy.

NOTE
Oracle tools will expect the full network resource name, including the domain, unless a default domain is specified in the sqlnet.ora configuration file. The names.default_domain parameter specifies what domain should be automatically added to any network resource name when resolving the resource name.n

For most installations, using a flat naming model (implemented with the .world default domain) is sufficient. Adding domains to your network topology should be done out of need, not just because it can be done. Managing an Oracle network with multiple domains adds complexity to the installation and configuration.

Understanding the Optional Security Extensions

The final set of Oracle Network Products includes several optional security extensions that make up the Oracle Advanced Networking Option. These include:

SQL*Net and Net8 Architectures

With the introduction of Oracle8, Oracle has renamed the current SQL*Net Network Product group to Net8. As mentioned previously, Oracle has introduced some new network performance and scalability features in the updated Net8 product. All other components and features in Net8 remain relatively unchanged from SQL*Net 2.3.3, the latest SQL*Net release for Oracle7 Release 7.3. In this discussion of Oracle networking fundamentals, I will be describing features and functions of SQL*Net 2.3.3. I will also be using the example of TCP/IP and ethernet in most examples, since these are the predominate network architectures. To make things as simple as possible, I will try to define all jargon and use analogies where possible.

In most of the current SQL*Net architecture diagrams, SQL*Net is shown as the central building block, tightly integrating network transport (Oracle Protocol Adapters), network naming (Naming Adapter), and security services (Oracle Advanced Networking Option) at the network level. User-client applications ride on top of this SQL*Net layer to access Oracle7 servers,

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