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How to apply CAC based on CPU & Memory Utilization to prevent gateway overload


The Call Admission Control (CAC) based on CPU Utilization feature permits the Cisco Voice Gateways to deny incoming calls exceeding a preconfigured threshold, permitting the selection of a system CPU load level value.


1.This feature helps ensure the quality of service of existing calls and reliability of Voice Gateway processes by preventing system overload caused by excessive incoming calls.

2.The Call Admission Control for H323 VoIP Gateways feature allows a user to configure thresholds for local resources as well as memory and CPU resources.

3.Maximum call capacity of the universal gateway is maintained using the Call treatment.

4.CPU and Memory load level is always maintained within the specified limit hence prevents overload.

Router #

call treatment on

call threshold poll-interval memory 4

call threshold global cpu-5sec low 80 high 90 treatment call threshold global

total-mem low 80 high 90 treatment

Call treatment enables the system to maintain the CPU and Memory threshold between 80-90 and if the calls exceeds, the system stops further calls to the gateway hence preventing the overload. Thus prevents the overload of the Gateway.

Note:- Threshold level for CPU & Memory can be set depending upon the type of network usage and you can measure using the following commands.

Router# show processes cpu history
Router# show call treatment config