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3CX on Hyper-V, clock skew, RTP problems

Discussion in '3CX Phone System - General' started by blabla, Apr 28, 2010.

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  1. blabla

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    Hi,

    I am running 3CX for a small installation on Windows Vista virtualized using Hyper-V.
    The VM is experiencing significant clock skew and as a result seems to have massive problems with RTP streams.
    The voice quality is simply horrible. Any solution to run 3CX in this environment.

    PS: Yes I could upgrade to a server OS, but since for example Vista and Windows 2008 ("R1") are using the same codebase there would also be clock skew (tested it).

    Regards
     
  2. FBW

    FBW New Member

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    If you mean by "clock skew" that your clock in the VM keeps changing then you should look into the settings of Hyper-V. It might be a good idea NOT to provide time from the hosting machine to the VM.
     
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  3. blabla

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    I already tried all combibations of Hyper-V component setting, to no avail.
     
  4. pjr

    pjr New Member

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    Are you using more than one virtual CPU?

    If so read here - http://wiki.3cx.com/documentation/troubleshooting/stuttering-voice-quality-in-hyperv-and-vmware

    I experienced the same thing - http://www.3cx.com/forums/running-3cx-in-a-virtualized-server-environment-11505.html
     
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  5. blabla

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    Hi, thanks for the reply. I've already read the article. The problem is that there seems to be no dpmtimer parameter after windows 2003 (vista an newer).
     
  6. SY

    SY Well-Known Member
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    Do you mean that the "performance and reliability monitor" doesn't work on your system correctly?
    Thanks
    P.S. The question is based on information provided in all of your posts, not only in the quoted one.
     
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  7. blabla

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    Hi I am sure why you are referring to the performance and reliability monitor.
    The problem is that Hyper-V seems to skew the clock and most likely the timing reference (whatever it is) 3CX is using for RTP timing, with the result that audio quality is horrible.
     
  8. SY

    SY Well-Known Member
    3CX Support

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    If you are sure then you can answer. Works good or not? (it is about performace monitor)
    It is not possible to discuss "Hyper-V seems to skew the clock" without concrete information from your host.
    The shortest wayto provide it is to make wireshark capture of the problematic call on the PBX host and post it here (Sip and RTP packets should be included)

    Also it will be good to know what is the hardware/software environment of your Hyper-V machine and host of this virtual machine.

    Thanks
     
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