Cisco ONS 15454 Series Multiservice Provisioning Platforms

Tune the CTC HEAP Variables on the PC to Improve CTC Performance


This document describes the procedure to tune certain system variables on the PC in order to improve the session performance of Cisco Transport Controller (CTC).



Cisco recommends that you have knowledge of these topics:

  • CTC

  • CTC supported platforms

Components Used

The information in this document is based on these software and hardware versions:

  • CTC

  • CTC supported platforms

The information in this document was created from the devices in a specific lab environment. All of the devices used in this document started with a cleared (default) configuration. If your network is live, make sure that you understand the potential impact of any command.


Refer to Cisco Technical Tips Conventions for more information on document conventions.

Tune the CTC HEAP Variables

The official stance of Cisco is that your network can contain 50 nodes or less per CTC session. You must use Cisco Transport Manager (CTM) for networks with more than 50 nodes. CTC cannot handle the additional processing. However, you can adjust certain variables on the PC to improve the overall CTC performance. This action can help with memory heap allocations on the PC. Cisco recommends these settings for the PC:

  1. Ensure that the PC has a minimum of one GB of physical RAM.

  2. Set the value for the CTC_HEAP environment variable to 512 MB. The default value is 128 MB.

  3. Set the value for the CTC_MAX_PERM_SIZE_HEAP environment variable to 128 MB. The default value is 64 MB.

  4. Control the number of concurrent applications on the same PC with CTC running. A higher number of applications degrades the overall system performance.

Step-by-step Procedure

Complete these steps in order to set the values for the CTC_HEAP and CTC_MAX_PERM_SIZE_HEAP variables:

  1. Choose Start > Control Panel > System.

    The System Properties window appears (see Figure 1).

    Figure 1—System Properties


  2. Go to the Advanced tab (see arrow A in Figure 1).

  3. Click Environment Variables (see arrow B in Figure 1).

    The Environment Variables window appears (see Figure 2)

    Figure 2—Environment Variables


    The list of system variables appears in the System variables section (see arrow A in Figure 2).

  4. Click New (see arrow B in Figure 2).

    The New System Variable window appears:

    Figure 3—New System Variable: CTC_HEAP


  5. Type CTC_HEAP in the Variable name field (see arrow B in Figure 3).

  6. Type 512 in the Variable value field (see arrow A in Figure 3).

  7. Click OK.

  8. Click New again in the System Environment Variables window.

  9. Type CTC_MAX_PERM_SIZE_HEAP in the System Variable name field (see arrow B in Figure 4).

  10. Type 128 in the Variable value field (see arrow A in Figure 4).

    Figure 4 – New System Variable: CTC_MAX_PERM_SIZE_HEAP


  11. Click OK.

  12. Check the Environment Variable window to verify the new values of CTC_HEAP and CTC_MAX_PERM_SIZE_HEAP (see the red rectangle in Figure 5).

    Figure 5—Environment Variables: CTC_HEAP and CTC_MAX_PERM_SIZE_HEAP


    CTC performance improves with these new values.

Verify the RAM Memory Installed on Your PC

Complete these steps to verify the total amount of RAM memory installed on your PC.

  1. Choose Start > Control Panel > System.

  2. Go to the General tab (see Figure 6).

  3. Inspect the hardware description at the bottom of the pane.

    You see the total amount of memory installed on your PC just under the processor speed. Insure you have at least 1 GB of RAM for optimal performance of CTC.

    Figure 6—System Window - General Tab


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