Configure Call Throttling

Call Throttling Overview

Call Throttling allows your system to automatically throttle or deny new call attempts. The system takes this action when conditions cause users to experience a delay in the interval between going off hook and receiving a dial tone.

Some factors that can result in this delay are as follows:

  • Heavy call activity

  • Low CPU availability

  • Routing loops

  • Disk I/O limitations

  • Disk fragmentation

The system uses the values that are specified in the call throttling parameters to determine a possible delay to dialtone and also to determine when conditions no longer require call throttling.

When throttling is necessary to prevent excessive delay to dialtone, the system enters a Code Yellow state and new call attempts are throttled (denied).

When the system calculates the delay to dialtone as being over the threshold that is configured in the call throttling service parameters, Unified Communications Manager rejects new calls. When call throttling activates, a user who attempts a new call receives a reorder tone and, depending on the phone model, may also receive a prompt on the phone display.

Call throttling effectively prevents the type of excessive delays that can cause a user to complain to the system administrator or question whether the system is down or the phone is broken. Your system constantly monitor the system to anticipate when such latency could occur.

When the delay to dialtone is within the guidelines of the call throttling service parameters, Unified Communications Manager stops throttling calls by exiting the Code Yellow state and new calls are again allowed.

Call Throttling Configuration Task Flow

Procedure

  Command or Action Purpose

Step 1

Configure Call Throttling

Enables Call throttling automatically when your system detects conditions such as heavy call activity, low CPU availability, and disk fragmentation.

Step 2

Configure Memory Throttling

Configures memory throttling for your system.

Configure Call Throttling

Call throttling occurs automatically when your system detects conditions such as heavy call activity, low CPU availability, and disk fragmentation. The system automatically exits throttling when these conditions are fixed. Call Throttling is configured via advanced service parameters. For many deployments, the default settings are sufficient.


Caution


We recommend that you not modify call throttling parameters unless advised to do so by customer support.

Procedure


Step 1

From Cisco Unified CM Administration, choose System > Service Parameters.

Step 2

From the Server drop-down list, choose a server.

Step 3

From the Service drop-down list, choose Cisco CallManager.

Step 4

Click Advanced.

Step 5

Under Call Throttling, configure values for the cll throttling service parameters. For parameter help descriptions, click the parameter name in the GUI.

  • Code Yellow Entry Latency
  • Code Yellow Exit Latency Calendar
  • Code Yellow Duration
  • Max Events Allowed
  • System Throttle Sample Size

Step 6

Click Save.


Configure Memory Throttling

Use this procedure to configure memory throttling for your system.

Procedure


Step 1

From Cisco Unified CM Administration, choose System > Service Parameters.

Step 2

From the Server drop-down list, select a Unified Communications Manager server.

Step 3

From the Service drop-down list, select Cisco CallManager.

Step 4

Click Advanced.

Step 5

Set the Enable Memory Throttling parameter to True.

Step 6

Configure values for the additional service parameters in the Memory Throttling area. For parameter help, click the parameter name in the GUI.

Step 7

Click Save.