Citrix Audio Over UDP Dropping mid session

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Citrix Audio Over UDP feature is great for improving audio performance in Citrix sessions and Ray Davis has a good article on how to get it working correctly link HERE. One issue I’ve come across recently is reports of audio failing to work mid-session. Often reported as audio dropping mid session.  The symptoms were if a user was in a call there the audio was working fine however after the call finished and another started all audio would drop from the session. No system audio, no voice app audio nothing. During the issue the audio devices attached to the Citrix session (headsets, mics speakers etc) were still showing as connected.

After a bit of digging we found the cause to be two things. due to the UDP nature of the audio after a period of audio inactivity the audio over UDP ports on the connecting firewalls shutdown terminating the audio. Also VDA versions prior to 1912 CU4 have no capability to maintain the UDP connection during periods of inactivity. In order to resolve this all the VDA’s need to be upgraded to 1912 CU4 and a registry key needs to be configured. Not sure why this isn’t I the default install for the vda but there we go.

Create a DWORD value of KeepAliveTimer in the following location HKEY_LOCAL_MACHINE\SOFTWARE\WOW6432Node\Citrix\Audio and set the value to a number. This number represents the number of seconds between UDP keep alive pings which will keep the UDP sessions active during the periods of inactivity somewhere.  

This also means that you need to talk to your network team and confirm what the firewall in between the clients and the endpoints have configured for UDP timeouts and adjust the registry value to be inside of that timeout. So for instance if networks say the UDP timeout is 30 seconds on their firewall the registry value you would set could be.

KeepAliveTimer DWORD 15

Once those are configured you should find that your audio works perfectly.

Author: Dale Scriven

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