Communicator QoS DSCP Marking on x64 Operating Systems

I never did manage to figure this one out. The registry key HKLM\Software\Microsoft\RTC\Transport\QoSEnabled=1 never seemed to take effect on x64 versions of Vista or Windows 7. Wireshark packet traces would show no tags, but x86 clients worked just fine. Turns out the registry key you need to set for this to work is under the WoW6432Node which makes a ton of sense after seeing it. The DWORD you need to set is this one:

HKLM\Software\WoW6432Node\Microsoft\RTC\Transport\QoSEnabled=1

Thanks to Matt McGillen for posting this originally.

Peanut Gallery

  1. 1 Ciantic

    I wonder does this apply to Windows 7 x64 too. The thing is I just can’t find registry entry “HKLM\Software\WoW6432Node\Microsoft\RTC” at all, the RTC just is not there.

    I’m having this problem where no matter what I put to QoS Policy settings in Group policy editor, the Wireshark shows the DSCP as 0×00.

     
  2. 2 Tom Pacyk

    Hi Ciantic, yes, it applies to Win7 x64 also. You have manually create the key structure first, because as you pointed out it does not exist by default. So you’ll need to create the RTC section and the QoS key before this will work.

     

Speak Up