5 Listener

You can use Enterprise Manager to manage Oracle Listener targets. From the Enterprise Manager Listener home page, you can monitor key metrics that can help determine the performance and availability of the listener and help you troubleshoot potential performance problems.

5.1 General Status

This metric is a container for a set of metrics that provide general information about the listener target. For more information, see the section on Listener Administration in the Oracle Database Net Services Administrator's Guide 10g Release 2 (10.2).

The following table lists the metrics, their descriptions, and data sources.

Table 5-1 General Status Metrics

Metric	Description	Data Source
Alias	Alternative name for the listener. On the Metric Detail page, you can see the value of this metric only when you select one of the Real Time refresh options. The alias also appears on the Listener home page.	Derived from the STATUS command of the Listener Control Utility
Security	Shows whether or not a password is required to run specific commands with the Listener Control Utility	Derived from the STATUS command of the Listener Control Utility
SID List	Lists the System Identifiers (SIDs) for the services monitored by the listener	List of SIDs for the listener is stored in the `listener.ora` configuration file
SNMP Status	Indicates whether or not the listener can respond to queries from an SNMP-based network management system	Derived from the `STATUS` command of the Listener Control Utility
Start Date	Represents the day and time when the listener was last started. On the Metric Detail page, you can see the value of this metric only when you select one of the Real Time refresh options. This metric also appears on the Enterprise Manager Listener home page.	Derived from the `STATUS` command of the Listener Control Utility
TNS Address	Displays the protocol, host, and port information for the listener. On the Metric Detail page, you can see the value of this metric only when you select one of the Real Time refresh options. The TNS address also appears on the Listener home page.	TNS address of the Listener is defined in the `listener.ora` configuration file
Trace Level	Represents the level of tracing currently enabled for the listener. Tracing can be used to troubleshoot problems with the listener by saving additional information to the trace file. For more information about the trace levels you can set for the listener, see the information about the Listener Control Utility in the Oracle Database Net Services Reference Guide 10g Release 2 (10.2). On the Metric Detail page, you can see the value of this metric only when you select one of the Real Time refresh options.	Derived from the `STATUS` command of the Listener Control Utility
Version	Version of the listener software. On the Metric Detail page, you can see the value of this metric only when you select one of the Real Time refresh options. This metric also appears on the Enterprise Manager Listener home page.	Derived from the `STATUS` command of the Listener Control Utility

5.2 Load

This metric is a container for a set of metrics that provide you with information about the number of connections supported by the Listener over a period of time. For more information, see the section on Listener Administration in the Oracle Database Net Services Administrator's Guide 10g Release 2 (10.2).

The following table lists the metrics, their descriptions, data sources, and user actions.

Table 5-2 Load Metrics

Metric	Description	Data Source	User Action
Connections Established	Number of connections established since the listener was last started	Derived from the `SERVICES` command of the Listener Control Utility	If you are noticing experiencing performance issues with the database or other services supported by the listener, review the historical values of this metric to determine whether or not the performance problems are caused by excessive load on the listener or host.
Connections Established (per min)	Average number of connections per minute that were established with the listener	Derived from the Listener Control Utility	If you are noticing experiencing performance issues with the database or other services supported by the listener, review the historical values of this metric to determine whether or not the performance problems are caused by excessive load on the listener or host.
Connections Refused	Number of connections to the listener that were refused. A connection can be refused for a variety of reasons, including situations where the database or other listener service is down, or if the connection timed out.	Derived from the `SERVICES` command of the Listener Control Utility	If Enterprise Manager reports a high number of refused connections, check the availability and performance of the database or other services supported by the listener.
Connections Refused (per min)	Average number of connections that were refused per minute	Derived from the Listener Control Utility	If Enterprise Manager reports a high number of refused connections, check the availability and performance of the database or other services supported by the listener.

5.3 Response

This metric is a container for the Response and Status metrics that provide you with performance information about the Listener.

5.3.1 Response Time (msec)

This metric represents the time (in milliseconds) that it takes for the Listener to respond to a network request (ping).

By default, this metric has a critical threshold of 100 and a warning threshold of 80. A critical alert is generated when the metric value exceeds the critical threshold value 1 time. A warning alert is generated when the metric value exceeds the warning threshold value 1 time. You can edit the value for a threshold as required.

By default, Enterprise Manager tests the value of this metric every 24 hours.

When an alert is generated, the alert text is:

Listener response to a TNS ping is %value% msecs

Data Source

The value of this metric is derived using the TNSPING command. For more information about the TNSPING command, see the Oracle Database Net Services Administrator's Guide 10g Release 2 (10.2).

User Action

If the Listener response time consistently exceeds the threshold, users are likely experiencing performance issues while accessing the database or other services on this host. Use the Enterprise Manager Central Console to review other performance indicators, such as the overall health of your database and the response time of your hosts and Web Applications.

5.3.2 Status

This metric returns a value of "1" if the Listener is up and running; it returns a 0 if the Listener is unavailable.

By default, this metric has a critical threshold of 0. A critical alert is generated when the metric value equals the critical threshold value 1 time. You can edit the value for a threshold as required.

By default, Enterprise Manager tests the value of this metric every 24 hours.

When an alert is generated, the alert text is:

The listener is down: %oraerr%.

Data Source

This metric is derived from the STATUS command in the Listener Control Utility. For more information, see the Oracle Database Net Services Administrator's Guide 10g Release 2 (10.2).

User Action

When the listener is down, users cannot access the database or other services on this host. Review the troubleshooting information in Oracle Database Net Services Administrator's Guide 10g Release 2 (10.2).