Sun Java System Application Server Enterprise Edition 8.1 2005Q2 High Availability Administration Guide

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## Unique Port Numbers and Configurations

If multiple instances on the same host machine reference the same configuration, each instance must listen on a unique port number. For example, if two server instances reference a named configuration with an HTTP listener on port 80, a port conflict prevents one of the server instances from starting. Change the properties that define the port numbers on which individual server instances listen so that unique ports are used.

The following principles apply to port numbers:

- Port numbers for individual server instances are initially inherited from the configuration.

- If the port is already in use when you create a server instance, override the inherited default value at the instance level to prevent port conflicts.

- Assume an instance is sharing a configuration. The configuration has port number n. If you create a new instance on the machine using the same configuration, the new instance is assigned port number n+1, if it is available. If it is not available, the next available port after n+1 is chosen.

- If you change the port number of the configuration, a server instance inheriting that port number automatically inherits the changed port number.

- If you change an instance’s port number and you subsequently change the configuration’s port number, the instance’s port number remains unchanged.

  For more information, see:

- To Edit Port Numbers for Instances Referencing a Configuration

- Editing a Named Configuration’s Properties

- Named Configurations

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