Net8 Administrator's Guide
Release 8.1.6

Part Number A76933-01





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Planning Your Network

Net8 provides a variety of options to help you design and manage networks that are both flexible and easy to use. With Net8's enhanced scalability and manageability features, you can develop a network to support a wide range of environments whether they be simple workgroups or large mission critical enterprises.

This chapter describes considerations for planning a network using Net8. It explains the relationships of the network products, and options for expanding and better managing your future network. It includes the following sections:

Planning Overview

Take the time to review and plan your network before you configure it. As you are planning your Oracle network, remember to keep future needs in mind as well as present requirements. Some of the more important decisions which you will need to make regarding your network include:

Defining Your Network Layout

The following checklist is provided to help you outline the main components of your network.

  1. Define from the outset what it is you hope to accomplish with your network.

  2. Research the functionality required by your client applications, then assess the resources that are available to meet those requirements.

  3. Determine which machines or nodes are best suited for client or server applications.

  4. Select a networking protocol which best suits your existing or future networking requirements. Protocols are available for most of the major protocols on many platforms. You may be able to choose a single transport level protocol that works well on all the components in your network. Your network may involve clients or servers operating over more than one protocol.

  5. If you decide to use multiple protocols on your network, determine which nodes are best suited to install Oracle Connection Manager. Your choice of nodes will be determined by the networking protocols you have chosen as well as the machine's capacity to handle anticipated traffic.

It helps sometimes to draw a picture of your network layout displaying the logical as well as physical relationships between networking components.

Resolving Names to Connect Descriptors

Once you have defined your network layout, you will need to decide how best to configure and manage your network implementation. One of the first and most important decisions that you will need to make is choosing a naming method.

The following table summarizes the relative advantages and disadvantages of each naming method and provides recommendations for using them in your network.

Naming Method  Advantages/Disadvantages  Recommended for: 

Local Naming 


  • Provides a relatively straightforward method for resolving net service name addresses

  • Resolves net service names across networks running different protocols

Disadvantage: Requires local configuration of all net service name and address changes 

Simple distributed networks with a small number of services that change infrequently. 

Directory Naming 


  • Centralizes network names and addresses in a single place, facilitating administration of name changes and updates. This eliminates the need for an administrator to make changes to what potentially could be hundreds or even thousands of clients.

  • Directory stores names for other services.

  • Tools provide simple configuration.

Disadvantage: Requires access to a directory server 

Large, complex networks (over 20 databases) that change on a frequent basis. 

Oracle Names 

Advantage: Centralizes network names and addresses in a single place, facilitating administration of name changes and updates. For example, whenever a change is made to an existing server or a new server is added to the network, the change is made only once on one Oracle Names server. This eliminates the need for an administrator to make changes to what potentially could be hundreds or even thousands of clients.


  • Oracle Names stores network names and addresses for Oracle services only.

  • Requires additional setup and administration of Oracle Names servers.


Large, complex networks (over 20 databases) that change on a frequent basis. 

Host Naming 


  • Requires minimal user configuration. The user may provide only the name of the host to establish a connection.

  • Eliminates the need to create and maintain a local names configuration file (tnsnames.ora).

Disadvantage: Available only in a limited environment, as indicated in the Recommended for column 

Simple TCP/IP networks that meet the criteria listed:

  • Your client and server are connecting using TCP/IP.

  • The host name is resolved through an IP address translation mechanism such as Domain Name Services (DNS), Network Information Services (NIS), or a centrally maintained TCP/IP hosts file.

  • No Oracle Connection Manager features are requested.


External Naming 

Advantage: Enables administrators to load Oracle net service name into their native name service using tools and utilities with which they are already familiar

Disadvantage: Requires a third-naming services that cannot be administered using Net8 products 

Networks with existing name services. 

Improving Large Network Performance

You may improve the performance of large networks by implementing any of the following:

Using Shared Servers or Prespawned Dedicated Servers

If you expect your network to receive a lot of connection traffic, you can use the listener to manage these requests by redirecting them to either multi-threaded server (MTS) shared servers or prespawned dedicated servers.

The following table summarizes the relative advantages of each, and provides recommendations for using them in your network.

Type  Advantages  Recommended for: 

MTS Shared servers 

  • Utilizes network resources more efficiently than a dedicated server, thus increasing the throughput and performance of your sessions

  • Enables you to minimize the memory and processing resources needed on the server side as the number of sessions to the database increases


Networks where MTS is supported, or where the creation of a new server process is slow and resource-intensive. 

Prestarted or prespawned dedicated servers  

  • Reduces connect time by eliminating the need to create a dedicated server for each new connection request

  • Provides better use of allocated memory and system resources by recycling servers for use by other connections without having to shut down and recreate a server process


Networks where MTS is not supported, or where the creation of a new server process is slow and resource-intensive. 

See Also:


Increasing Listener Queuesize

If you anticipate receiving a large number of connection requests for a listening process (such as a listener, Oracle Connection Manager or Oracle Names) over TCP/IP, Net8 enables you to configure the listening queue to be higher than the system default.

See Also:

"Handling Large Volumes of Connection Requests" for information about configuring the existing queuesize 

Enabling Connection Pooling

Connection pooling is a resource utilization feature that enables you to maximize the number of physical network connections to a multi-threaded server. This is achieved by sharing or pooling a dispatcher's set of connections among multiple client processes.

By using a time-out mechanism to temporarily release transport connections that have been idle for a specified period of time, connection pooling makes these physical connections available for incoming clients, while still maintaining a logical session with the previous idle connection. When the idle client has more work to do, the physical connection is reestablished with the dispatcher.

This feature only works when multi-threaded server is configured.

See Also:


Enabling Connection Concentration

Connection concentration is a feature that is available through Oracle Connection Manager. It enables you take advantage of Oracle Connection Manager's ability to multiplex or funnel multiple client sessions over a single transport to a multi-threaded server. Like connection pooling, connection concentration optimizes network resources and increases the number of client-server sessions that are possible across a fixed number of physical server ports. Unlike connection pooling, connection concentration maintains the transport connection.

See Also:


Using Connection Pooling and Connection Concentration

The following table summarizes the relative advantages of using connection pooling and connection concentration and provides recommendations for using them in your network.

Feature  Advantages  Recommended for: 

Connection Pooling 

  • Limits the number of network resources used per process

  • Maximizes the number of client/server sessions over a limited number of physical connections

  • Optimizes resource utilization


Networks where many clients run interactive "high think/search time" applications such as messaging and OLAP 

Connection Concentration 

  • Supports large client populations.

  • Enables identification and monitoring of real users.

  • Enables mid-tier applications to support additional services.

  • Requires only a single transport for clients with multiple applications.

  • Requires only a single network connection for database links.


Networks where "continuous" connectivity is required. 

Enabling Client Load Balancing

When more than one listener supports a service, a client can be configured to randomize requests to the various listeners. The randomization serves to distribute the load so as not to overburden a single listener. By balancing the load, you can improve connection performance.

See Also:

"Configuring Address List Parameters" for configuration details 

Adjusting the Session Data Unit (SDU) Size for Data Transfer Optimization

Tuning your application to reduce the number of round trips across the network is the best way to improve your network performance. If this is done, it is also possible to optimize data transfer by adjusting the size of the session data unit (SDU).

The SDU is a buffer that Net8 uses to place data before transmitting it across the network. Net8 sends the data in the buffer either when requested or when it is full.

The following table outlines considerations when modifying the size of the SDU may or may not be appropriate.

Modify SDU size when:  Do not modify SDU size when: 
  • The data coming back from the server is fragmented into separate packets

  • You are on a wide area network (WAN) that has long delays

  • Your packet size is consistently the same

  • Large amounts of data are returned

  • Your application can be tuned to account for the delays

  • You have a higher speed network where the effect of the data transmission is negligible

  • Your requests return small amounts of data from the server



The SDU size should be set as a multiple of the normal transport frame size. Since the normal Ethernet frame size is 1500, the most efficient SDU size over an Ethernet protocol should be a multiple of 1500.

If you are using either connection pooling or connection concentration, keep in mind that these features require an additional 16 bytes per transport. For more information about the protocol frame size, refer to your operating-system-specific documentation. 

See Also:

"Configuring Advanced Connect Data Parameters" for configuration details 

Persistent Buffer Flushing for TCP/IP

Under certain conditions in some applications using TCP/IP, Net8 packets may not get flushed immediately to the network. Most often, this behavior occurs when large amounts of data are streamed from one end to another. The implementation of TCP/IP itself is the reason for the lack of flushing, and can cause unacceptable delays. To remedy this problem, you can specify no delays in the buffer flushing process.

See Also:

"TCP.NODELAY" for information about this parameter 

Planning Summary

The table below summarizes many of the options you may have chosen as you planned your network.

Subject  Options 

Network Layout 

  • Single or Multiple Protocols


Net Service Name Resolution 

  • Local Naming

  • Directory Naming

  • Oracle Names

  • Host Naming

  • External Naming


Connection Request Management 

  • Shared Servers

  • Prespawned Dedicated Servers


Network Performance 

  • Increasing Listener queuesize

  • Enabling Client Load Balancing

  • Enabling Connection Pooling

  • Enabling Client Load Balancing

  • Adjusting the SDU Size

  • Persistent Buffer Flushing


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