MSRTPTOS does not add DSCP tags under Windows 7

Discussion in '3CX Phone System - General' started by mcbsys, May 28, 2011.

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  1. mcbsys

    mcbsys New Member

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    Hi,

    I'm running 3CX v9.0.13545.594 SP.5a under a Windows 7 VM.

    I know that Vista/Windows 7 can do policy-based tagging, but according to this TechNet article is that if Group Policy is not configured, "By default, computers running Windows Vista and Windows Server 2008 allow applications to specify DSCP values."

    So under Settings > Advanced > Custom Parameters, I set MSRTPTOS to 46. But when I view the packets coming from 3CX in Wireshark (viewed through a mirrored destination port at the switch), they are all tagged with DSCP 0.

    I know this blog post http://www.3cx.com/blog/voip-howto/qos-windows-2008-server-local-policy/ says to do it through Group Policy, but shouldn't it work without Group Policy? Has anyone gotten this to work?

    I prefer the simpler, native implementation if available.

    Thanks,
     
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  2. mcbsys

    mcbsys New Member

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    Hmm...wondering if no one is using QoS under Windows 7? Or just not using native 3CX QoS? Maybe the native only works under XP?
     
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  3. SY

    SY Well-Known Member
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    "Native" may work only under XP/2003 (if you allow it by changing "registry")
    In Vista/2008/W7 - this method was banned.
    2008/W7 had banned QoS API, which was available for 2003/Vista, once again .

    The best way (at this moment) is to use standard approach to adjust QoS as described in the article.
     
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  4. thetester

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    Please check http://ask.wireshark.org/questions/1188/why-is-dscp-always-0-on-windows-7 (and comments)
     
  5. mcbsys

    mcbsys New Member

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    Thanks. Yes, I found that article before. However that person could not set DSCP using policy, and the answer was to circumvent the domain-joined requirement. In my case this is a domain-joined machine so applying Group Policy is not an issue and DSCP works fine when set through policy.

    I did modify the procedure a bit so I only tag packets coming from 3CX. Blogged here:

    Setting Up QoS for 3CX under Windows 7
    http://www.mcbsys.com/techblog/2011/06/setting-up-qos-for-3cx-under-windows-7
     
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