Cisco TelePresence MCU 4200 Series

Using VNC with Cisco TelePresence MCU

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Using VNC with Cisco TelePresence MCUs

You can add VNC (Virtual Network Computing) endpoints to the MCU. This enables you to have software applications running on a remote computer added to a conference. For example, if a speaker has a set of slides to present during a conference, you can add them as a VNC endpoint.

You can configure a VNC endpoint on the MCU by choosing Endpoints > Add VNC. This makes it easier to add a VNC session to conferences because you can choose its name from a list rather than type its network address.

This article covers:

Recommended VNC servers

We recommend the following VNC servers for use with the Cisco TelePresence MCU:

  • RealVNC
  • UltraVNC
  • TightVNC

All of these products can be downloaded for free.


Download version 4 or later from the website.

For information about installing and configuring RealVNC, see the Cisco web site for the Cisco TelePresence MCU Series Tutorial.

Note: RealVNC does not support dual-monitor setup (i.e. Extended Desktop).


Download version or later from the website.

For setup information, visit the website above and go to HOME > Installation > Installation instructions.

Although UltraVNC can connect to the MCU with dual-monitor setup, it can only display the primary monitor.


Download version 1.3.10 or later from the website.

For setup information, go to: Start Menu > All Programs > TightVNC > Documentation > Installation and Getting Started.

Although TightVNC can connect to the MCU with dual-monitor setup, it can only display the primary monitor.

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Supported VNC resolutions

The MCU can receive VGA (640x480), SVGA (800x600) and XGA (1024x768) and UXGA (1600x1200) resolutions from a VNC server.

Although most VNC servers can support resolutions up to 1600 x 1200, we recommend using a lower resolution. This is because high resolutions may not always display well on all endpoints.

Note: If you change the resolution of your desktop while in a conference the VNC server will be disconnected.

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Controlling the VNC resolution

The MCU will use whatever VNC resolution it is sent. VNC servers will usually send the same resolution as the screen that they are serving; therefore to alter the VNC resolution you must change the resolution of the display that is being served. To do this:

  • Windows: right-click on the screen and select Properties. A new dialog appears: click the Settings tab, select the display that is being used and use the slider in the lower left of the dialog to select your desired resolution
  • Mac: select System preferences from the Apple menu, and click Displays. A display configuration window appears on each screen that can be independently configured. There is a list of available resolutions on the left side of the Displays configuration window: select the desired resolution for that display from the list for the screen that is to be served

Note: Changing the resolution will cause the VNC connection to close and may cause your VNC server to quit. Ensure your VNC server is running before attempting to reconnect.


If the computer uses a 1024 x 768, the MCU will detect this and display it at the appropriate scaled size on other participants' views. You do not need to control the VNC resolution manually because the MCU will cope with any size up to the maximum 1600 x 1200.

Note: The displayed proportions change for widescreen VNC connections to 4:3, distorting the picture. To avoid this, use a 4:3 resolution by altering the resolution on your computer as described above.

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Troubleshooting VNC problems

If you notice a problem (for example, what you see on participants' displays is incorrectly scaled), there could be a compatibility issue between the VNC program you are using and the MCU's VNC implementation.

Cisco TAC will need the following information to troubleshoot any incompatibilities:

  • The Cisco TelePresence MCU software version you are running (this is shown on the Status > General page)
  • The VNC program and software version you are running
  • An event log

To obtain a suitable event log:

  1. Start from an MCU with no active H.323 or VNC connections (from a restart would be ideal).
  2. In the web interface go to Logs > Event capture filter.
  3. Change the VNC setting to Errors, warnings, information, and trace.
  4. Click Update settings.
  5. Establish the VNC connection again from the MCU web interface. Verify that the same fault condition exists.
  6. Go to Logs > Event log, and click Download as text.

Send the resulting text file to Cisco customer support.

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This article applies to the following products:

  • Cisco TelePresence MCU 4200 / MSE 8420
  • Cisco TelePresence MCU 4500
  • Cisco TelePresence MSE 8510 blade

April 12th, 2011 TAA_KB_32