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Cisco TelePresence MCU 4200 Series

'Port limit exceeded' message when there are fewer than MCUs maximum number of participants connected

Why do I get the message 'Port limit exceeded' when I have fewer than my Cisco TelePresence MCU's maximum number of participants connected?

This article applies to the following products:

  • Cisco TelePresence MCU 4200 Series
  • Cisco TelePresence MCU 4500 Series
  • Cisco TelePresence MCU 5300 Series
  • Cisco TelePresence MCU MSE Series
  • Cisco TelePresence ConferenceMe

Circumstances in which video ports are used for video and other purposes

In some circumstances, the MCU will use an available video port for content or streaming. The true maximum number of (video) participants is only the same as the maximum number of (video) ports if the MCU does not need to use a video port for content. A VNC connection also uses a port (whether it is currently providing content or not).

Each of the following can consume video ports:

  • Typical video participants (video-enabled hardware or software endpoints)
  • ConferenceMe connections
  • VNC connections
  • Multicast streams
  • Unicast streams
  • Content channels

The circumstances in which an MCU will use a video port, for reasons other than to enable a typical video participant, are as follows:

  • The MCU does not have dedicated streaming and content ports, but content is required:

    Applies to MCU MSE 8420, MCU 5300 Series, and MCU 4200 Series (except MCU 4203). If these MCUs are in port reservation mode, they will reserve a video port for content for each conference that has content enabled - irrespective of whether content is currently being provided to that conference. Otherwise, the video port will only be taken when the content starts (provided that there is one available).

  • The MCU does not have dedicated streaming and content ports, but streaming is required:

    Applies to MCU MSE 8420 and MCU 4200 Series (except MCU 4203). If either ConferenceMe or Streaming is enabled, then each ConferenceMe connection or each stream consumes a video port.

    If multicast streaming is enabled, then a video port is consumed when the conference becomes active, irrespective of whether the stream is being viewed.

    If unicast streaming is enabled, a video port is only consumed when at least one conference viewer has requested unicast streaming.

  • The MCU does not have dedicated streaming and content ports in the current media port mode, but content or streaming is required:

    Applies to MCU 4500 Series when operating in the HD or HD+ media port modes. Applies to MCU MSE 8510 in nHD, SD, HD+, or Full HD media port modes.

    The content channel or stream will consume a port when required. If port reservation is enabled, then a video port is reserved for each conference that has content enabled.

    If multicast streaming is enabled, then a video port is consumed when the conference becomes active, irrespective of whether the stream is being viewed.

    If unicast streaming is enabled, a video port is only consumed when at least one conference viewer has requested unicast streaming.

  • The MCU does not have dedicated audio-only ports in the current media port mode, but an audio-only participant joins:

    Applies to MCU MSE 8510 and MCU 5300 Series. These MCUs do not have dedicated audio-only ports when operating in the nHD or SD media port modes. Each audio-only participant will consume a video port.

How to maximize video ports

To maximize the number of video ports available for video participants, you can try the following:

  • Change the media port mode, on the Settings > Media ports page.
  • Disable ConferenceMe, or reduce the number of ConferenceMe participants that can connect at a time, on the Settings > Streaming page.
  • Disable content for your particular conference, but not MCU-wide, on the conference configuration page.
  • Disable content MCU-wide on the Settings > Content page.
  • Disable streaming for your particular conference, but not MCU-wide, on the conference configuration page.
  • Disable streaming MCU-wide on the Settings > Streaming page.

See also

  • The MCU port matrix topic in the MCU online help and administration guide.
  • The streaming and content topics in the MCU online help and administration guide.

  • October 16th, 2012 TAA_KB_57