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VXC 6215 Citrix HDX MediaStream Flash Redirection Troubleshooting


Detail Configuration Steps

Verification and Troubleshooting

Verifying where flash content is rendered (Client or Server)

If the flash is rendered on the client, once the user is able to  login to the machine they can then open a 32-bit version of Internet  Explorer and browse to a Flash site such as YouTube. When a video starts  playing and they try and move the windowed Internet Explorer the Flash  section should move almost independently (Not in sync) to the main  window and then snap into place as the thin client window receives  redraw instructions from Citrix. Another way is to take a screen shot or  print screen for the Internet Explorer with flash content loaded, when  the flash content is rendering in the client, the screen shot will only  show the black ground for the flash section as if the flash is not  loaded.This will verify the Flash redirection section of the policy.

If the flash is rendered on the server (HVD), the flash section in  the Internet explorer will move in sync with the Internet explorer  window, and if you take a screen shot, the flash content is also get  captured in the screen shot

Verifying server-side or client-side fetching

To verify the server side content fetching a networking tool such as  tcpdump or wireshark will allow you to see if there are packets going  from the thin client. You can find the TCPDump add-on in this post for  installing on the 6215 client, To run this just use the command  ‘tcpdump’ as root and it will show all network traffic. To see only HTTP  traffic you can use the filter / command ‘tcpdump tcp port 80’. This  will show if the thin client is trying to make a connection to YouTube  or a similar Flash hosting site. If Flash redirection with client side  rendering and server side fetching is in place then you should see no  HTTP traffic while playing the Flash video.

If you are unable to use packet capture tools then blocking access  to the particular Flash hosting site from the switch / router the thin  client is connected to should suffice, the user should still be able to  see the Flash content with the block in place.


1. Citrix HDX user policies settings control the behaviour of the  flash redirection. These policies settings can be deployed and applied  via either Citrix Dekstop Studio or Active Directory Group Policy  Object. Ensure these two approaches of deploying settings do not clash  with each other.

2. Flash Redirection measures the round trip latency between the  server and user device the first time an individual browser or browser  tab accesses an embedded Flash Player. This measurement includes both  the latency of the network connection and any other latency in the data  path. If the latency is determined to be within an acceptable threshold,  Flash Redirection is used to render Flash content on the user device.  If the latency is above this threshold, the Flash content rendering  fallback to server side. The default threshold setting is 30  milliseconds

To change the default threshold settings, edit the Flash Redirection  policy and add "Flash latency threshold" setting to the policy and  specify the value to be above 30 milliseconds e.g 100

3. Enable Flash event logging to allow Flash events to be recorded  in the Windows application event log. On computers running Windows 7 or  Windows Vista, a Flash Redirection-specific log appears in the  Applications and Services Log node. And you can check out the event logs  in HVD to find out why a certain flash instance is not behaving as what  you expected.

4. If you experienced audio break up issue when having graphic  movement in HVD, check and verify the flash content is rendering on the  client, not on the server. It is also good to check if the USB headset  device is redirected to HVD by checking the HVD Win OS device manager to  see if the usb headset is recognized by HVD. 6215 thin client should  control the USB device locally for audio playback, and hence the USB  headset should not needed to be redirected to HVD.

5. Ensure the flash player installed on HVD and on thin client are  on the same major version (e.g 11.x), and compatible with each other.

Version history
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Last update:
‎01-13-2013 05:34 PM
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