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Cisco MCU show error the message "Media marker bits unreliable" in MCU for one of the endpoints.

Cisco sx20 call to the meeting room in MCU . MCU show error message "Media marker bits unreliable" in MCU for one of the endpoints . Sometime is picture are flashing. We change the new device at original site the problem have still. I thought that may be root casue of network because I take the equipment installed in the other room . MCU not show error message "Media marker bits unreliable" . 



As the problem is gone when

As the problem is gone when you move it to a different room it also sounds to me that its a network issue.


Is there anything different / special with the network in this room? Like different subnet,

different firewall, ...


Is there something special in or for that room? Did you check  that the network cables, the patch cable, but also the fixed installation in the room, as well as the switch config and physical port are ok?






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Hi , we are also seeing

Hi , we are also seeing "media marker bits unreliable" on a MCU call specifically when a Lync client joins the call. has anyone else seen this behaviour? or knows what may cause this ?




Media marker bits are used as

Media marker bits are used as part of RTP to indicate when you have reached the end of a single frame, this is primarily used for video streams where single frames cannot fit within a single packet MTU.

The specification for RTP states that these bits should not be relied upon, so the MCU is also able to check the timestamps associated with each packet and will display this message if packets are incorrectly marked as the end of a frame. Currently I am unaware of any cases where an SX20 produces such invalid bitstreams, but we are aware of cases where other endpoints can produce such results. Was the endpoint from your other conference room also an SX20 running the same software version?

Could you confirm exactly what endpoints were present in the conference as well as any software versions? The version of your MCU software and hardware will also help in diagnosing this problem.

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