Chapter 15 Overload Protection

Communications Server provides the overload protection feature to protect systems from overload situations. A typical form of overload protection/load regulation is to reject certain types of requests when the load increases. Depending on the overload situation, certain requests are prioritized and certain requests are rejected to decrease the load in the system. In an overload situation, for instance, Communications Server could reject new SIP sessions so that ongoing sessions are prioritized.

To enable overload protection, set the olpInserted property to true. By default, this value this set to false. Use the following command to set this property:

asadmin set config.sip-container.property.olpInserted=true

Communications Server offers two types of load regulation:

• CPU Overload Protection

• Memory Overload Protection

CPU Overload Protection

Communications Server enables you to regulate incoming HTTP and SIP requests based on the CPU load. CPU overload protection can be activated or de-activated both during installation and in runtime.

To enable CPU overload protection, set the CPUOverLoadRegulation property to true. By default, this value this set to false. Use the following command to set this property:

asadmin set config.sip-container.property.CPUOverLoadRegulation=true

You can configure the following threshold levels:

• HttpThreshold - All incoming HTTP requests are rejected and 503 responses are sent out, when this threshold is exceeded.

• IrThreshold - Initial incoming requests are rejected and 503 responses are sent out when this threshold is exceeded.

• SrThreshold - All incoming SIP requests are rejected and 503 responses are sent out, when this threshold is exceeded.

• MmThreshold - All incoming HTTP and SIP requests are rejected when this threshold is exceeded.

• SampleRate - Interval or periodicity of the measurement of CPU usage.

• NumberOfSamples -Number of samples that the CPU usage has to be above the threshold level to trigger an action of either dropping the request or sending 503 responses.

For details about these properties, such as default value and allowed values see TBDlink.

These CPU load regulation properties are applicable only if the CPUOverLoadRegulation property needs to be set to true. To view and set these values, use the asadmin get and set commands. For example, you can use the following command to set the value of the IrThreshold property:

asadmin set config.sip-container.property.IrThreshold=80

Memory Overload Protection

Communications Server enables you to regulate incoming HTTP and SIP requests based on the memory usage. Memory overload protection can be activated or de-activated both during installation and in runtime.

To enable memory overload protection, set the MemOverLoadRegulation property to true. By default, this value this set to false. Use the following command to set this property:

asadmin set config.sip-container.property.MemOverLoadRegulation=true

You can configure the following threshold levels:

• MemHttpThreshold - All incoming HTTP requests are rejected and 503 responses are sent out, when this threshold is exceeded.

• MemIrThreshold - Initial incoming requests are rejected and 503 responses are sent out when this threshold is exceeded.

• MemMmThreshold - All incoming HTTP and SIP requests are rejected when this threshold is exceeded.